[PATCH 3/7] percpu: clean up percpu variable definitions

[PATCH 3/7] percpu: clean up percpu variable definitions

[Tejun Heo]

Percpu variable definition is about to be updated such that

* percpu symbols must be unique even the static ones

* in-function static definition is not allowed

Update percpu variable definitions accoringly.

* as,cfq: rename ioc_count uniquely

* cpufreq: rename cpu_dbs_info uniquely

* xen: move nesting_count out of xen_evtchn_do_upcall() and rename it

* mm: move ratelimits out of balance_dirty_pages_ratelimited_nr() and
  rename it

* ipv4,6: rename cookie_scratch uniquely

While at it, make cris:use DECLARE_PER_CPU() instead of extern
volatile DEFINE_PER_CPU() for declaration.

[ Impact: percpu usage cleanups, no duplicate static percpu var names ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: linux-mm <linux-mm@kvack.org>
Cc: David S. Miller <davem@davemloft.net>
---
 arch/cris/include/asm/mmu_context.h    |    2 +-
 block/as-iosched.c                     |   10 +++++-----
 block/cfq-iosched.c                    |   10 +++++-----
 drivers/cpufreq/cpufreq_conservative.c |   12 ++++++------
 drivers/cpufreq/cpufreq_ondemand.c     |   15 ++++++++-------
 drivers/xen/events.c                   |    9 +++++----
 mm/page-writeback.c                    |    5 +++--
 net/ipv4/syncookies.c                  |    4 ++--
 net/ipv6/syncookies.c                  |    4 ++--
 9 files changed, 37 insertions(+), 34 deletions(-)

diff --git a/arch/cris/include/asm/mmu_context.h b/arch/cris/include/asm/mmu_context.h
index 72ba08d..00de1a0 100644
--- a/arch/cris/include/asm/mmu_context.h
+++ b/arch/cris/include/asm/mmu_context.h
@@ -17,7 +17,7 @@ extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
  * registers like cr3 on the i386
  */
 
-extern volatile DEFINE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
+DECLARE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
 
 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 {
diff --git a/block/as-iosched.c b/block/as-iosched.c
index c48fa67..96ff4d1 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -146,7 +146,7 @@ enum arq_state {
 #define RQ_STATE(rq)	((enum arq_state)(rq)->elevator_private2)
 #define RQ_SET_STATE(rq, state)	((rq)->elevator_private2 = (void *) state)
 
-static DEFINE_PER_CPU(unsigned long, ioc_count);
+static DEFINE_PER_CPU(unsigned long, as_ioc_count);
 static struct completion *ioc_gone;
 static DEFINE_SPINLOCK(ioc_gone_lock);
 
@@ -161,7 +161,7 @@ static void as_antic_stop(struct as_data *ad);
 static void free_as_io_context(struct as_io_context *aic)
 {
 	kfree(aic);
-	elv_ioc_count_dec(ioc_count);
+	elv_ioc_count_dec(as_ioc_count);
 	if (ioc_gone) {
 		/*
 		 * AS scheduler is exiting, grab exit lock and check
@@ -169,7 +169,7 @@ static void free_as_io_context(struct as_io_context *aic)
 		 * complete ioc_gone and set it back to NULL.
 		 */
 		spin_lock(&ioc_gone_lock);
-		if (ioc_gone && !elv_ioc_count_read(ioc_count)) {
+		if (ioc_gone && !elv_ioc_count_read(as_ioc_count)) {
 			complete(ioc_gone);
 			ioc_gone = NULL;
 		}
@@ -211,7 +211,7 @@ static struct as_io_context *alloc_as_io_context(void)
 		ret->seek_total = 0;
 		ret->seek_samples = 0;
 		ret->seek_mean = 0;
-		elv_ioc_count_inc(ioc_count);
+		elv_ioc_count_inc(as_ioc_count);
 	}
 
 	return ret;
@@ -1509,7 +1509,7 @@ static void __exit as_exit(void)
 	ioc_gone = &all_gone;
 	/* ioc_gone's update must be visible before reading ioc_count */
 	smp_wmb();
-	if (elv_ioc_count_read(ioc_count))
+	if (elv_ioc_count_read(as_ioc_count))
 		wait_for_completion(&all_gone);
 	synchronize_rcu();
 }
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index a55a9bd..deea748 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -48,7 +48,7 @@ static int cfq_slice_idle = HZ / 125;
 static struct kmem_cache *cfq_pool;
 static struct kmem_cache *cfq_ioc_pool;
 
-static DEFINE_PER_CPU(unsigned long, ioc_count);
+static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
 static struct completion *ioc_gone;
 static DEFINE_SPINLOCK(ioc_gone_lock);
 
@@ -1423,7 +1423,7 @@ static void cfq_cic_free_rcu(struct rcu_head *head)
 	cic = container_of(head, struct cfq_io_context, rcu_head);
 
 	kmem_cache_free(cfq_ioc_pool, cic);
-	elv_ioc_count_dec(ioc_count);
+	elv_ioc_count_dec(cfq_ioc_count);
 
 	if (ioc_gone) {
 		/*
@@ -1432,7 +1432,7 @@ static void cfq_cic_free_rcu(struct rcu_head *head)
 		 * complete ioc_gone and set it back to NULL
 		 */
 		spin_lock(&ioc_gone_lock);
-		if (ioc_gone && !elv_ioc_count_read(ioc_count)) {
+		if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
 			complete(ioc_gone);
 			ioc_gone = NULL;
 		}
@@ -1558,7 +1558,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
 		INIT_HLIST_NODE(&cic->cic_list);
 		cic->dtor = cfq_free_io_context;
 		cic->exit = cfq_exit_io_context;
-		elv_ioc_count_inc(ioc_count);
+		elv_ioc_count_inc(cfq_ioc_count);
 	}
 
 	return cic;
@@ -2663,7 +2663,7 @@ static void __exit cfq_exit(void)
 	 * this also protects us from entering cfq_slab_kill() with
 	 * pending RCU callbacks
 	 */
-	if (elv_ioc_count_read(ioc_count))
+	if (elv_ioc_count_read(cfq_ioc_count))
 		wait_for_completion(&all_gone);
 	cfq_slab_kill();
 }
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index 2ecd95e..e0faa3e 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -80,7 +80,7 @@ struct cpu_dbs_info_s {
 	int cpu;
 	unsigned int enable:1;
 };
-static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
+static DEFINE_PER_CPU(struct cpu_dbs_info_s, cs_cpu_dbs_info);
 
 static unsigned int dbs_enable;	/* number of CPUs using this policy */
 
@@ -150,7 +150,7 @@ dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 		     void *data)
 {
 	struct cpufreq_freqs *freq = data;
-	struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info,
+	struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cs_cpu_dbs_info,
 							freq->cpu);
 
 	struct cpufreq_policy *policy;
@@ -323,7 +323,7 @@ static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
 	/* we need to re-evaluate prev_cpu_idle */
 	for_each_online_cpu(j) {
 		struct cpu_dbs_info_s *dbs_info;
-		dbs_info = &per_cpu(cpu_dbs_info, j);
+		dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 		dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
 						&dbs_info->prev_cpu_wall);
 		if (dbs_tuners_ins.ignore_nice)
@@ -413,7 +413,7 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 		cputime64_t cur_wall_time, cur_idle_time;
 		unsigned int idle_time, wall_time;
 
-		j_dbs_info = &per_cpu(cpu_dbs_info, j);
+		j_dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 
 		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
 
@@ -553,7 +553,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 	unsigned int j;
 	int rc;
 
-	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
+	this_dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
 
 	switch (event) {
 	case CPUFREQ_GOV_START:
@@ -573,7 +573,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 
 		for_each_cpu(j, policy->cpus) {
 			struct cpu_dbs_info_s *j_dbs_info;
-			j_dbs_info = &per_cpu(cpu_dbs_info, j);
+			j_dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 			j_dbs_info->cur_policy = policy;
 
 			j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 338f428..2eaf88f 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -87,7 +87,7 @@ struct cpu_dbs_info_s {
 	unsigned int enable:1,
 		sample_type:1;
 };
-static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
+static DEFINE_PER_CPU(struct cpu_dbs_info_s, od_cpu_dbs_info);
 
 static unsigned int dbs_enable;	/* number of CPUs using this policy */
 
@@ -162,7 +162,8 @@ static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
 	unsigned int freq_hi, freq_lo;
 	unsigned int index = 0;
 	unsigned int jiffies_total, jiffies_hi, jiffies_lo;
-	struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, policy->cpu);
+	struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
+						   policy->cpu);
 
 	if (!dbs_info->freq_table) {
 		dbs_info->freq_lo = 0;
@@ -207,7 +208,7 @@ static void ondemand_powersave_bias_init(void)
 {
 	int i;
 	for_each_online_cpu(i) {
-		struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, i);
+		struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, i);
 		dbs_info->freq_table = cpufreq_frequency_get_table(i);
 		dbs_info->freq_lo = 0;
 	}
@@ -322,7 +323,7 @@ static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
 	/* we need to re-evaluate prev_cpu_idle */
 	for_each_online_cpu(j) {
 		struct cpu_dbs_info_s *dbs_info;
-		dbs_info = &per_cpu(cpu_dbs_info, j);
+		dbs_info = &per_cpu(od_cpu_dbs_info, j);
 		dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
 						&dbs_info->prev_cpu_wall);
 		if (dbs_tuners_ins.ignore_nice)
@@ -416,7 +417,7 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 		unsigned int load, load_freq;
 		int freq_avg;
 
-		j_dbs_info = &per_cpu(cpu_dbs_info, j);
+		j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
 
 		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
 
@@ -573,7 +574,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 	unsigned int j;
 	int rc;
 
-	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
+	this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 
 	switch (event) {
 	case CPUFREQ_GOV_START:
@@ -595,7 +596,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 
 		for_each_cpu(j, policy->cpus) {
 			struct cpu_dbs_info_s *j_dbs_info;
-			j_dbs_info = &per_cpu(cpu_dbs_info, j);
+			j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
 			j_dbs_info->cur_policy = policy;
 
 			j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 30963af..4dbe5c0 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -596,6 +596,8 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static DEFINE_PER_CPU(unsigned, xed_nesting_count);
+
 /*
  * Search the CPUs pending events bitmasks.  For each one found, map
  * the event number to an irq, and feed it into do_IRQ() for
@@ -611,7 +613,6 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
 	struct pt_regs *old_regs = set_irq_regs(regs);
 	struct shared_info *s = HYPERVISOR_shared_info;
 	struct vcpu_info *vcpu_info = __get_cpu_var(xen_vcpu);
-	static DEFINE_PER_CPU(unsigned, nesting_count);
  	unsigned count;
 
 	exit_idle();
@@ -622,7 +623,7 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
 
 		vcpu_info->evtchn_upcall_pending = 0;
 
-		if (__get_cpu_var(nesting_count)++)
+		if (__get_cpu_var(xed_nesting_count)++)
 			goto out;
 
 #ifndef CONFIG_X86 /* No need for a barrier -- XCHG is a barrier on x86. */
@@ -647,8 +648,8 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
 
 		BUG_ON(!irqs_disabled());
 
-		count = __get_cpu_var(nesting_count);
-		__get_cpu_var(nesting_count) = 0;
+		count = __get_cpu_var(xed_nesting_count);
+		__get_cpu_var(xed_nesting_count) = 0;
 	} while(count != 1);
 
 out:
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index bb553c3..0e0c9de 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -606,6 +606,8 @@ void set_page_dirty_balance(struct page *page, int page_mkwrite)
 	}
 }
 
+static DEFINE_PER_CPU(unsigned long, bdp_ratelimits) = 0;
+
 /**
  * balance_dirty_pages_ratelimited_nr - balance dirty memory state
  * @mapping: address_space which was dirtied
@@ -623,7 +625,6 @@ void set_page_dirty_balance(struct page *page, int page_mkwrite)
 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 					unsigned long nr_pages_dirtied)
 {
-	static DEFINE_PER_CPU(unsigned long, ratelimits) = 0;
 	unsigned long ratelimit;
 	unsigned long *p;
 
@@ -636,7 +637,7 @@ void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 	 * tasks in balance_dirty_pages(). Period.
 	 */
 	preempt_disable();
-	p =  &__get_cpu_var(ratelimits);
+	p =  &__get_cpu_var(bdp_ratelimits);
 	*p += nr_pages_dirtied;
 	if (unlikely(*p >= ratelimit)) {
 		*p = 0;
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index b35a950..70ee18c 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -37,12 +37,12 @@ __initcall(init_syncookies);
 #define COOKIEBITS 24	/* Upper bits store count */
 #define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
 
-static DEFINE_PER_CPU(__u32, cookie_scratch)[16 + 5 + SHA_WORKSPACE_WORDS];
+static DEFINE_PER_CPU(__u32, ipv4_cookie_scratch)[16 + 5 + SHA_WORKSPACE_WORDS];
 
 static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
 		       u32 count, int c)
 {
-	__u32 *tmp = __get_cpu_var(cookie_scratch);
+	__u32 *tmp = __get_cpu_var(ipv4_cookie_scratch);
 
 	memcpy(tmp + 4, syncookie_secret[c], sizeof(syncookie_secret[c]));
 	tmp[0] = (__force u32)saddr;
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 711175e..348e38c 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -74,12 +74,12 @@ static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
 	return child;
 }
 
-static DEFINE_PER_CPU(__u32, cookie_scratch)[16 + 5 + SHA_WORKSPACE_WORDS];
+static DEFINE_PER_CPU(__u32, ipv6_cookie_scratch)[16 + 5 + SHA_WORKSPACE_WORDS];
 
 static u32 cookie_hash(struct in6_addr *saddr, struct in6_addr *daddr,
 		       __be16 sport, __be16 dport, u32 count, int c)
 {
-	__u32 *tmp = __get_cpu_var(cookie_scratch);
+	__u32 *tmp = __get_cpu_var(ipv6_cookie_scratch);
 
 	/*
 	 * we have 320 bits of information to hash, copy in the remaining
-- 
1.6.0.2

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Re: [PATCH 3/7] percpu: clean up percpu variable definitions

[Jens Axboe]

On Wed, May 20 2009, Tejun Heo wrote:
> Percpu variable definition is about to be updated such that
> 
> * percpu symbols must be unique even the static ones
> 
> * in-function static definition is not allowed
> 
> Update percpu variable definitions accoringly.
> 
> * as,cfq: rename ioc_count uniquely
> 
> * cpufreq: rename cpu_dbs_info uniquely
> 
> * xen: move nesting_count out of xen_evtchn_do_upcall() and rename it
> 
> * mm: move ratelimits out of balance_dirty_pages_ratelimited_nr() and
>   rename it
> 
> * ipv4,6: rename cookie_scratch uniquely
> 
> While at it, make cris:use DECLARE_PER_CPU() instead of extern
> volatile DEFINE_PER_CPU() for declaration.
> 
> [ Impact: percpu usage cleanups, no duplicate static percpu var names ]

The block bits looks fine.

Acked-by: Jens Axboe <jens.axboe@oracle.com>

> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
> Cc: Jens Axboe <jens.axboe@oracle.com>
> Cc: Dave Jones <davej@redhat.com>
> Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
> Cc: linux-mm <linux-mm@kvack.org>
> Cc: David S. Miller <davem@davemloft.net>
> ---
>  arch/cris/include/asm/mmu_context.h    |    2 +-
>  block/as-iosched.c                     |   10 +++++-----
>  block/cfq-iosched.c                    |   10 +++++-----
>  drivers/cpufreq/cpufreq_conservative.c |   12 ++++++------
>  drivers/cpufreq/cpufreq_ondemand.c     |   15 ++++++++-------
>  drivers/xen/events.c                   |    9 +++++----
>  mm/page-writeback.c                    |    5 +++--
>  net/ipv4/syncookies.c                  |    4 ++--
>  net/ipv6/syncookies.c                  |    4 ++--
>  9 files changed, 37 insertions(+), 34 deletions(-)
> 
> diff --git a/arch/cris/include/asm/mmu_context.h b/arch/cris/include/asm/mmu_context.h
> index 72ba08d..00de1a0 100644
> --- a/arch/cris/include/asm/mmu_context.h
> +++ b/arch/cris/include/asm/mmu_context.h
> @@ -17,7 +17,7 @@ extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
>   * registers like cr3 on the i386
>   */
>  
> -extern volatile DEFINE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
> +DECLARE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
>  
>  static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
>  {
> diff --git a/block/as-iosched.c b/block/as-iosched.c
> index c48fa67..96ff4d1 100644
> --- a/block/as-iosched.c
> +++ b/block/as-iosched.c
> @@ -146,7 +146,7 @@ enum arq_state {
>  #define RQ_STATE(rq)	((enum arq_state)(rq)->elevator_private2)
>  #define RQ_SET_STATE(rq, state)	((rq)->elevator_private2 = (void *) state)
>  
> -static DEFINE_PER_CPU(unsigned long, ioc_count);
> +static DEFINE_PER_CPU(unsigned long, as_ioc_count);
>  static struct completion *ioc_gone;
>  static DEFINE_SPINLOCK(ioc_gone_lock);
>  
> @@ -161,7 +161,7 @@ static void as_antic_stop(struct as_data *ad);
>  static void free_as_io_context(struct as_io_context *aic)
>  {
>  	kfree(aic);
> -	elv_ioc_count_dec(ioc_count);
> +	elv_ioc_count_dec(as_ioc_count);
>  	if (ioc_gone) {
>  		/*
>  		 * AS scheduler is exiting, grab exit lock and check
> @@ -169,7 +169,7 @@ static void free_as_io_context(struct as_io_context *aic)
>  		 * complete ioc_gone and set it back to NULL.
>  		 */
>  		spin_lock(&ioc_gone_lock);
> -		if (ioc_gone && !elv_ioc_count_read(ioc_count)) {
> +		if (ioc_gone && !elv_ioc_count_read(as_ioc_count)) {
>  			complete(ioc_gone);
>  			ioc_gone = NULL;
>  		}
> @@ -211,7 +211,7 @@ static struct as_io_context *alloc_as_io_context(void)
>  		ret->seek_total = 0;
>  		ret->seek_samples = 0;
>  		ret->seek_mean = 0;
> -		elv_ioc_count_inc(ioc_count);
> +		elv_ioc_count_inc(as_ioc_count);
>  	}
>  
>  	return ret;
> @@ -1509,7 +1509,7 @@ static void __exit as_exit(void)
>  	ioc_gone = &all_gone;
>  	/* ioc_gone's update must be visible before reading ioc_count */
>  	smp_wmb();
> -	if (elv_ioc_count_read(ioc_count))
> +	if (elv_ioc_count_read(as_ioc_count))
>  		wait_for_completion(&all_gone);
>  	synchronize_rcu();
>  }
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index a55a9bd..deea748 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -48,7 +48,7 @@ static int cfq_slice_idle = HZ / 125;
>  static struct kmem_cache *cfq_pool;
>  static struct kmem_cache *cfq_ioc_pool;
>  
> -static DEFINE_PER_CPU(unsigned long, ioc_count);
> +static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
>  static struct completion *ioc_gone;
>  static DEFINE_SPINLOCK(ioc_gone_lock);
>  
> @@ -1423,7 +1423,7 @@ static void cfq_cic_free_rcu(struct rcu_head *head)
>  	cic = container_of(head, struct cfq_io_context, rcu_head);
>  
>  	kmem_cache_free(cfq_ioc_pool, cic);
> -	elv_ioc_count_dec(ioc_count);
> +	elv_ioc_count_dec(cfq_ioc_count);
>  
>  	if (ioc_gone) {
>  		/*
> @@ -1432,7 +1432,7 @@ static void cfq_cic_free_rcu(struct rcu_head *head)
>  		 * complete ioc_gone and set it back to NULL
>  		 */
>  		spin_lock(&ioc_gone_lock);
> -		if (ioc_gone && !elv_ioc_count_read(ioc_count)) {
> +		if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
>  			complete(ioc_gone);
>  			ioc_gone = NULL;
>  		}
> @@ -1558,7 +1558,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
>  		INIT_HLIST_NODE(&cic->cic_list);
>  		cic->dtor = cfq_free_io_context;
>  		cic->exit = cfq_exit_io_context;
> -		elv_ioc_count_inc(ioc_count);
> +		elv_ioc_count_inc(cfq_ioc_count);
>  	}
>  
>  	return cic;
> @@ -2663,7 +2663,7 @@ static void __exit cfq_exit(void)
>  	 * this also protects us from entering cfq_slab_kill() with
>  	 * pending RCU callbacks
>  	 */
> -	if (elv_ioc_count_read(ioc_count))
> +	if (elv_ioc_count_read(cfq_ioc_count))
>  		wait_for_completion(&all_gone);
>  	cfq_slab_kill();
>  }
> diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
> index 2ecd95e..e0faa3e 100644
> --- a/drivers/cpufreq/cpufreq_conservative.c
> +++ b/drivers/cpufreq/cpufreq_conservative.c
> @@ -80,7 +80,7 @@ struct cpu_dbs_info_s {
>  	int cpu;
>  	unsigned int enable:1;
>  };
> -static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
> +static DEFINE_PER_CPU(struct cpu_dbs_info_s, cs_cpu_dbs_info);
>  
>  static unsigned int dbs_enable;	/* number of CPUs using this policy */
>  
> @@ -150,7 +150,7 @@ dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
>  		     void *data)
>  {
>  	struct cpufreq_freqs *freq = data;
> -	struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info,
> +	struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cs_cpu_dbs_info,
>  							freq->cpu);
>  
>  	struct cpufreq_policy *policy;
> @@ -323,7 +323,7 @@ static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
>  	/* we need to re-evaluate prev_cpu_idle */
>  	for_each_online_cpu(j) {
>  		struct cpu_dbs_info_s *dbs_info;
> -		dbs_info = &per_cpu(cpu_dbs_info, j);
> +		dbs_info = &per_cpu(cs_cpu_dbs_info, j);
>  		dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
>  						&dbs_info->prev_cpu_wall);
>  		if (dbs_tuners_ins.ignore_nice)
> @@ -413,7 +413,7 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
>  		cputime64_t cur_wall_time, cur_idle_time;
>  		unsigned int idle_time, wall_time;
>  
> -		j_dbs_info = &per_cpu(cpu_dbs_info, j);
> +		j_dbs_info = &per_cpu(cs_cpu_dbs_info, j);
>  
>  		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
>  
> @@ -553,7 +553,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
>  	unsigned int j;
>  	int rc;
>  
> -	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
> +	this_dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
>  
>  	switch (event) {
>  	case CPUFREQ_GOV_START:
> @@ -573,7 +573,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
>  
>  		for_each_cpu(j, policy->cpus) {
>  			struct cpu_dbs_info_s *j_dbs_info;
> -			j_dbs_info = &per_cpu(cpu_dbs_info, j);
> +			j_dbs_info = &per_cpu(cs_cpu_dbs_info, j);
>  			j_dbs_info->cur_policy = policy;
>  
>  			j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
> diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
> index 338f428..2eaf88f 100644
> --- a/drivers/cpufreq/cpufreq_ondemand.c
> +++ b/drivers/cpufreq/cpufreq_ondemand.c
> @@ -87,7 +87,7 @@ struct cpu_dbs_info_s {
>  	unsigned int enable:1,
>  		sample_type:1;
>  };
> -static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
> +static DEFINE_PER_CPU(struct cpu_dbs_info_s, od_cpu_dbs_info);
>  
>  static unsigned int dbs_enable;	/* number of CPUs using this policy */
>  
> @@ -162,7 +162,8 @@ static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
>  	unsigned int freq_hi, freq_lo;
>  	unsigned int index = 0;
>  	unsigned int jiffies_total, jiffies_hi, jiffies_lo;
> -	struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, policy->cpu);
> +	struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
> +						   policy->cpu);
>  
>  	if (!dbs_info->freq_table) {
>  		dbs_info->freq_lo = 0;
> @@ -207,7 +208,7 @@ static void ondemand_powersave_bias_init(void)
>  {
>  	int i;
>  	for_each_online_cpu(i) {
> -		struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, i);
> +		struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, i);
>  		dbs_info->freq_table = cpufreq_frequency_get_table(i);
>  		dbs_info->freq_lo = 0;
>  	}
> @@ -322,7 +323,7 @@ static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
>  	/* we need to re-evaluate prev_cpu_idle */
>  	for_each_online_cpu(j) {
>  		struct cpu_dbs_info_s *dbs_info;
> -		dbs_info = &per_cpu(cpu_dbs_info, j);
> +		dbs_info = &per_cpu(od_cpu_dbs_info, j);
>  		dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
>  						&dbs_info->prev_cpu_wall);
>  		if (dbs_tuners_ins.ignore_nice)
> @@ -416,7 +417,7 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
>  		unsigned int load, load_freq;
>  		int freq_avg;
>  
> -		j_dbs_info = &per_cpu(cpu_dbs_info, j);
> +		j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
>  
>  		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
>  
> @@ -573,7 +574,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
>  	unsigned int j;
>  	int rc;
>  
> -	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
> +	this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
>  
>  	switch (event) {
>  	case CPUFREQ_GOV_START:
> @@ -595,7 +596,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
>  
>  		for_each_cpu(j, policy->cpus) {
>  			struct cpu_dbs_info_s *j_dbs_info;
> -			j_dbs_info = &per_cpu(cpu_dbs_info, j);
> +			j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
>  			j_dbs_info->cur_policy = policy;
>  
>  			j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
> diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> index 30963af..4dbe5c0 100644
> --- a/drivers/xen/events.c
> +++ b/drivers/xen/events.c
> @@ -596,6 +596,8 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
>  
> +static DEFINE_PER_CPU(unsigned, xed_nesting_count);
> +
>  /*
>   * Search the CPUs pending events bitmasks.  For each one found, map
>   * the event number to an irq, and feed it into do_IRQ() for
> @@ -611,7 +613,6 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
>  	struct pt_regs *old_regs = set_irq_regs(regs);
>  	struct shared_info *s = HYPERVISOR_shared_info;
>  	struct vcpu_info *vcpu_info = __get_cpu_var(xen_vcpu);
> -	static DEFINE_PER_CPU(unsigned, nesting_count);
>   	unsigned count;
>  
>  	exit_idle();
> @@ -622,7 +623,7 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
>  
>  		vcpu_info->evtchn_upcall_pending = 0;
>  
> -		if (__get_cpu_var(nesting_count)++)
> +		if (__get_cpu_var(xed_nesting_count)++)
>  			goto out;
>  
>  #ifndef CONFIG_X86 /* No need for a barrier -- XCHG is a barrier on x86. */
> @@ -647,8 +648,8 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
>  
>  		BUG_ON(!irqs_disabled());
>  
> -		count = __get_cpu_var(nesting_count);
> -		__get_cpu_var(nesting_count) = 0;
> +		count = __get_cpu_var(xed_nesting_count);
> +		__get_cpu_var(xed_nesting_count) = 0;
>  	} while(count != 1);
>  
>  out:
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index bb553c3..0e0c9de 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -606,6 +606,8 @@ void set_page_dirty_balance(struct page *page, int page_mkwrite)
>  	}
>  }
>  
> +static DEFINE_PER_CPU(unsigned long, bdp_ratelimits) = 0;
> +
>  /**
>   * balance_dirty_pages_ratelimited_nr - balance dirty memory state
>   * @mapping: address_space which was dirtied
> @@ -623,7 +625,6 @@ void set_page_dirty_balance(struct page *page, int page_mkwrite)
>  void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
>  					unsigned long nr_pages_dirtied)
>  {
> -	static DEFINE_PER_CPU(unsigned long, ratelimits) = 0;
>  	unsigned long ratelimit;
>  	unsigned long *p;
>  
> @@ -636,7 +637,7 @@ void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
>  	 * tasks in balance_dirty_pages(). Period.
>  	 */
>  	preempt_disable();
> -	p =  &__get_cpu_var(ratelimits);
> +	p =  &__get_cpu_var(bdp_ratelimits);
>  	*p += nr_pages_dirtied;
>  	if (unlikely(*p >= ratelimit)) {
>  		*p = 0;
> diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
> index b35a950..70ee18c 100644
> --- a/net/ipv4/syncookies.c
> +++ b/net/ipv4/syncookies.c
> @@ -37,12 +37,12 @@ __initcall(init_syncookies);
>  #define COOKIEBITS 24	/* Upper bits store count */
>  #define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
>  
> -static DEFINE_PER_CPU(__u32, cookie_scratch)[16 + 5 + SHA_WORKSPACE_WORDS];
> +static DEFINE_PER_CPU(__u32, ipv4_cookie_scratch)[16 + 5 + SHA_WORKSPACE_WORDS];
>  
>  static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
>  		       u32 count, int c)
>  {
> -	__u32 *tmp = __get_cpu_var(cookie_scratch);
> +	__u32 *tmp = __get_cpu_var(ipv4_cookie_scratch);
>  
>  	memcpy(tmp + 4, syncookie_secret[c], sizeof(syncookie_secret[c]));
>  	tmp[0] = (__force u32)saddr;
> diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
> index 711175e..348e38c 100644
> --- a/net/ipv6/syncookies.c
> +++ b/net/ipv6/syncookies.c
> @@ -74,12 +74,12 @@ static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
>  	return child;
>  }
>  
> -static DEFINE_PER_CPU(__u32, cookie_scratch)[16 + 5 + SHA_WORKSPACE_WORDS];
> +static DEFINE_PER_CPU(__u32, ipv6_cookie_scratch)[16 + 5 + SHA_WORKSPACE_WORDS];
>  
>  static u32 cookie_hash(struct in6_addr *saddr, struct in6_addr *daddr,
>  		       __be16 sport, __be16 dport, u32 count, int c)
>  {
> -	__u32 *tmp = __get_cpu_var(cookie_scratch);
> +	__u32 *tmp = __get_cpu_var(ipv6_cookie_scratch);
>  
>  	/*
>  	 * we have 320 bits of information to hash, copy in the remaining
> -- 
> 1.6.0.2
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

-- 
Jens Axboe

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Re: [PATCH 3/7] percpu: clean up percpu variable definitions

[Rusty Russell]

On Wed, 20 May 2009 05:07:35 pm Tejun Heo wrote:
> Percpu variable definition is about to be updated such that
>
> * percpu symbols must be unique even the static ones
>
> * in-function static definition is not allowed

That spluttering noise is be choking on the title of this patch :)

Making these pseudo statics is in no way a cleanup.  How about we just
say "they can't be static" and do something like:

/* Sorry, can't be static: that breaks archs which need these weak. */
#define DEFINE_PER_CPU(type, var) \
	extern typeof(type) var; DEFINE_PER_CPU_SECTION(type, name, "")

Thanks,
Rusty.

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Re: [PATCH 3/7] percpu: clean up percpu variable definitions

[Tejun Heo]

Rusty Russell wrote:
> On Wed, 20 May 2009 05:07:35 pm Tejun Heo wrote:
>> Percpu variable definition is about to be updated such that
>>
>> * percpu symbols must be unique even the static ones
>>
>> * in-function static definition is not allowed
> 
> That spluttering noise is be choking on the title of this patch :)
> 
> Making these pseudo statics is in no way a cleanup.  How about we just
> say "they can't be static" and do something like:
> 
> /* Sorry, can't be static: that breaks archs which need these weak. */
> #define DEFINE_PER_CPU(type, var) \
> 	extern typeof(type) var; DEFINE_PER_CPU_SECTION(type, name, "")

Heh... well, even though I authored the patch, I kind of agree with
you.  Maybe it would be better to simply disallow static declaration /
definition at all.  I wanted to give a go at the original idea as it
seemed to have some potential.  The result isn't too disappointing but
I can't really say there are distinctively compelling advantages to
justify the added complexity and subtlety.

What do others think?  Is everyone happy with going extern only?

Thanks.

-- 
tejun

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[PATCH 3/7] percpu: clean up percpu variable definitions

[Tejun Heo]

Percpu variable definition is about to be updated such that no static
declaration is allowed.  Update percpu variable definitions
accoringly.

* as,cfq: rename ioc_count uniquely

* cpufreq: rename cpu_dbs_info uniquely

* xen: move nesting_count out of xen_evtchn_do_upcall() and rename it

* mm: move ratelimits out of balance_dirty_pages_ratelimited_nr() and
  rename it

* ipv4,6: rename cookie_scratch uniquely

While at it, make cris:use DECLARE_PER_CPU() instead of extern
volatile DEFINE_PER_CPU() for declaration.

[ Impact: percpu usage cleanups, no duplicate static percpu var names ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: linux-mm <linux-mm@kvack.org>
Cc: David S. Miller <davem@davemloft.net>
---
 arch/cris/include/asm/mmu_context.h    |    2 +-
 block/as-iosched.c                     |   10 +++++-----
 block/cfq-iosched.c                    |   10 +++++-----
 drivers/cpufreq/cpufreq_conservative.c |   12 ++++++------
 drivers/cpufreq/cpufreq_ondemand.c     |   15 ++++++++-------
 drivers/xen/events.c                   |    9 +++++----
 mm/page-writeback.c                    |    5 +++--
 net/ipv4/syncookies.c                  |    5 +++--
 net/ipv6/syncookies.c                  |    5 +++--
 9 files changed, 39 insertions(+), 34 deletions(-)

diff --git a/arch/cris/include/asm/mmu_context.h b/arch/cris/include/asm/mmu_context.h
index 72ba08d..00de1a0 100644
--- a/arch/cris/include/asm/mmu_context.h
+++ b/arch/cris/include/asm/mmu_context.h
@@ -17,7 +17,7 @@ extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
  * registers like cr3 on the i386
  */
 
-extern volatile DEFINE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
+DECLARE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
 
 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 {
diff --git a/block/as-iosched.c b/block/as-iosched.c
index c48fa67..96ff4d1 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -146,7 +146,7 @@ enum arq_state {
 #define RQ_STATE(rq)	((enum arq_state)(rq)->elevator_private2)
 #define RQ_SET_STATE(rq, state)	((rq)->elevator_private2 = (void *) state)
 
-static DEFINE_PER_CPU(unsigned long, ioc_count);
+static DEFINE_PER_CPU(unsigned long, as_ioc_count);
 static struct completion *ioc_gone;
 static DEFINE_SPINLOCK(ioc_gone_lock);
 
@@ -161,7 +161,7 @@ static void as_antic_stop(struct as_data *ad);
 static void free_as_io_context(struct as_io_context *aic)
 {
 	kfree(aic);
-	elv_ioc_count_dec(ioc_count);
+	elv_ioc_count_dec(as_ioc_count);
 	if (ioc_gone) {
 		/*
 		 * AS scheduler is exiting, grab exit lock and check
@@ -169,7 +169,7 @@ static void free_as_io_context(struct as_io_context *aic)
 		 * complete ioc_gone and set it back to NULL.
 		 */
 		spin_lock(&ioc_gone_lock);
-		if (ioc_gone && !elv_ioc_count_read(ioc_count)) {
+		if (ioc_gone && !elv_ioc_count_read(as_ioc_count)) {
 			complete(ioc_gone);
 			ioc_gone = NULL;
 		}
@@ -211,7 +211,7 @@ static struct as_io_context *alloc_as_io_context(void)
 		ret->seek_total = 0;
 		ret->seek_samples = 0;
 		ret->seek_mean = 0;
-		elv_ioc_count_inc(ioc_count);
+		elv_ioc_count_inc(as_ioc_count);
 	}
 
 	return ret;
@@ -1509,7 +1509,7 @@ static void __exit as_exit(void)
 	ioc_gone = &all_gone;
 	/* ioc_gone's update must be visible before reading ioc_count */
 	smp_wmb();
-	if (elv_ioc_count_read(ioc_count))
+	if (elv_ioc_count_read(as_ioc_count))
 		wait_for_completion(&all_gone);
 	synchronize_rcu();
 }
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index a55a9bd..deea748 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -48,7 +48,7 @@ static int cfq_slice_idle = HZ / 125;
 static struct kmem_cache *cfq_pool;
 static struct kmem_cache *cfq_ioc_pool;
 
-static DEFINE_PER_CPU(unsigned long, ioc_count);
+static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
 static struct completion *ioc_gone;
 static DEFINE_SPINLOCK(ioc_gone_lock);
 
@@ -1423,7 +1423,7 @@ static void cfq_cic_free_rcu(struct rcu_head *head)
 	cic = container_of(head, struct cfq_io_context, rcu_head);
 
 	kmem_cache_free(cfq_ioc_pool, cic);
-	elv_ioc_count_dec(ioc_count);
+	elv_ioc_count_dec(cfq_ioc_count);
 
 	if (ioc_gone) {
 		/*
@@ -1432,7 +1432,7 @@ static void cfq_cic_free_rcu(struct rcu_head *head)
 		 * complete ioc_gone and set it back to NULL
 		 */
 		spin_lock(&ioc_gone_lock);
-		if (ioc_gone && !elv_ioc_count_read(ioc_count)) {
+		if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
 			complete(ioc_gone);
 			ioc_gone = NULL;
 		}
@@ -1558,7 +1558,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
 		INIT_HLIST_NODE(&cic->cic_list);
 		cic->dtor = cfq_free_io_context;
 		cic->exit = cfq_exit_io_context;
-		elv_ioc_count_inc(ioc_count);
+		elv_ioc_count_inc(cfq_ioc_count);
 	}
 
 	return cic;
@@ -2663,7 +2663,7 @@ static void __exit cfq_exit(void)
 	 * this also protects us from entering cfq_slab_kill() with
 	 * pending RCU callbacks
 	 */
-	if (elv_ioc_count_read(ioc_count))
+	if (elv_ioc_count_read(cfq_ioc_count))
 		wait_for_completion(&all_gone);
 	cfq_slab_kill();
 }
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index 7a74d17..8191d04 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -80,7 +80,7 @@ struct cpu_dbs_info_s {
 	int cpu;
 	unsigned int enable:1;
 };
-static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
+static DEFINE_PER_CPU(struct cpu_dbs_info_s, cs_cpu_dbs_info);
 
 static unsigned int dbs_enable;	/* number of CPUs using this policy */
 
@@ -153,7 +153,7 @@ dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 		     void *data)
 {
 	struct cpufreq_freqs *freq = data;
-	struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info,
+	struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cs_cpu_dbs_info,
 							freq->cpu);
 
 	struct cpufreq_policy *policy;
@@ -326,7 +326,7 @@ static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
 	/* we need to re-evaluate prev_cpu_idle */
 	for_each_online_cpu(j) {
 		struct cpu_dbs_info_s *dbs_info;
-		dbs_info = &per_cpu(cpu_dbs_info, j);
+		dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 		dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
 						&dbs_info->prev_cpu_wall);
 		if (dbs_tuners_ins.ignore_nice)
@@ -416,7 +416,7 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 		cputime64_t cur_wall_time, cur_idle_time;
 		unsigned int idle_time, wall_time;
 
-		j_dbs_info = &per_cpu(cpu_dbs_info, j);
+		j_dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 
 		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
 
@@ -556,7 +556,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 	unsigned int j;
 	int rc;
 
-	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
+	this_dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
 
 	switch (event) {
 	case CPUFREQ_GOV_START:
@@ -576,7 +576,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 
 		for_each_cpu(j, policy->cpus) {
 			struct cpu_dbs_info_s *j_dbs_info;
-			j_dbs_info = &per_cpu(cpu_dbs_info, j);
+			j_dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 			j_dbs_info->cur_policy = policy;
 
 			j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index e741c33..04de476 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -87,7 +87,7 @@ struct cpu_dbs_info_s {
 	unsigned int enable:1,
 		sample_type:1;
 };
-static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
+static DEFINE_PER_CPU(struct cpu_dbs_info_s, od_cpu_dbs_info);
 
 static unsigned int dbs_enable;	/* number of CPUs using this policy */
 
@@ -165,7 +165,8 @@ static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
 	unsigned int freq_hi, freq_lo;
 	unsigned int index = 0;
 	unsigned int jiffies_total, jiffies_hi, jiffies_lo;
-	struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, policy->cpu);
+	struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
+						   policy->cpu);
 
 	if (!dbs_info->freq_table) {
 		dbs_info->freq_lo = 0;
@@ -210,7 +211,7 @@ static void ondemand_powersave_bias_init(void)
 {
 	int i;
 	for_each_online_cpu(i) {
-		struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, i);
+		struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, i);
 		dbs_info->freq_table = cpufreq_frequency_get_table(i);
 		dbs_info->freq_lo = 0;
 	}
@@ -325,7 +326,7 @@ static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
 	/* we need to re-evaluate prev_cpu_idle */
 	for_each_online_cpu(j) {
 		struct cpu_dbs_info_s *dbs_info;
-		dbs_info = &per_cpu(cpu_dbs_info, j);
+		dbs_info = &per_cpu(od_cpu_dbs_info, j);
 		dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
 						&dbs_info->prev_cpu_wall);
 		if (dbs_tuners_ins.ignore_nice)
@@ -419,7 +420,7 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 		unsigned int load, load_freq;
 		int freq_avg;
 
-		j_dbs_info = &per_cpu(cpu_dbs_info, j);
+		j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
 
 		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
 
@@ -576,7 +577,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 	unsigned int j;
 	int rc;
 
-	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
+	this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 
 	switch (event) {
 	case CPUFREQ_GOV_START:
@@ -598,7 +599,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 
 		for_each_cpu(j, policy->cpus) {
 			struct cpu_dbs_info_s *j_dbs_info;
-			j_dbs_info = &per_cpu(cpu_dbs_info, j);
+			j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
 			j_dbs_info->cur_policy = policy;
 
 			j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 228a8bb..dbfed85 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -596,6 +596,8 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static DEFINE_PER_CPU(unsigned, xed_nesting_count);
+
 /*
  * Search the CPUs pending events bitmasks.  For each one found, map
  * the event number to an irq, and feed it into do_IRQ() for
@@ -611,7 +613,6 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
 	struct pt_regs *old_regs = set_irq_regs(regs);
 	struct shared_info *s = HYPERVISOR_shared_info;
 	struct vcpu_info *vcpu_info = __get_cpu_var(xen_vcpu);
-	static DEFINE_PER_CPU(unsigned, nesting_count);
  	unsigned count;
 
 	exit_idle();
@@ -622,7 +623,7 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
 
 		vcpu_info->evtchn_upcall_pending = 0;
 
-		if (__get_cpu_var(nesting_count)++)
+		if (__get_cpu_var(xed_nesting_count)++)
 			goto out;
 
 #ifndef CONFIG_X86 /* No need for a barrier -- XCHG is a barrier on x86. */
@@ -647,8 +648,8 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
 
 		BUG_ON(!irqs_disabled());
 
-		count = __get_cpu_var(nesting_count);
-		__get_cpu_var(nesting_count) = 0;
+		count = __get_cpu_var(xed_nesting_count);
+		__get_cpu_var(xed_nesting_count) = 0;
 	} while(count != 1);
 
 out:
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index bb553c3..0e0c9de 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -606,6 +606,8 @@ void set_page_dirty_balance(struct page *page, int page_mkwrite)
 	}
 }
 
+static DEFINE_PER_CPU(unsigned long, bdp_ratelimits) = 0;
+
 /**
  * balance_dirty_pages_ratelimited_nr - balance dirty memory state
  * @mapping: address_space which was dirtied
@@ -623,7 +625,6 @@ void set_page_dirty_balance(struct page *page, int page_mkwrite)
 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 					unsigned long nr_pages_dirtied)
 {
-	static DEFINE_PER_CPU(unsigned long, ratelimits) = 0;
 	unsigned long ratelimit;
 	unsigned long *p;
 
@@ -636,7 +637,7 @@ void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 	 * tasks in balance_dirty_pages(). Period.
 	 */
 	preempt_disable();
-	p =  &__get_cpu_var(ratelimits);
+	p =  &__get_cpu_var(bdp_ratelimits);
 	*p += nr_pages_dirtied;
 	if (unlikely(*p >= ratelimit)) {
 		*p = 0;
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index ce629ed..a3c045c 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -37,12 +37,13 @@ __initcall(init_syncookies);
 #define COOKIEBITS 24	/* Upper bits store count */
 #define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
 
-static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS], cookie_scratch);
+static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS],
+		      ipv4_cookie_scratch);
 
 static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
 		       u32 count, int c)
 {
-	__u32 *tmp = __get_cpu_var(cookie_scratch);
+	__u32 *tmp = __get_cpu_var(ipv4_cookie_scratch);
 
 	memcpy(tmp + 4, syncookie_secret[c], sizeof(syncookie_secret[c]));
 	tmp[0] = (__force u32)saddr;
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 4d995fe..e2bcff0 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -74,12 +74,13 @@ static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
 	return child;
 }
 
-static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS], cookie_scratch);
+static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS],
+		      ipv6_cookie_scratch);
 
 static u32 cookie_hash(struct in6_addr *saddr, struct in6_addr *daddr,
 		       __be16 sport, __be16 dport, u32 count, int c)
 {
-	__u32 *tmp = __get_cpu_var(cookie_scratch);
+	__u32 *tmp = __get_cpu_var(ipv6_cookie_scratch);
 
 	/*
 	 * we have 320 bits of information to hash, copy in the remaining
-- 
1.6.0.2

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Re: [PATCH 3/7] percpu: clean up percpu variable definitions

[David Miller]

From: Tejun Heo <tj@kernel.org>
Date: Mon,  1 Jun 2009 17:58:24 +0900

> --- a/arch/cris/include/asm/mmu_context.h
> +++ b/arch/cris/include/asm/mmu_context.h
> @@ -17,7 +17,7 @@ extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
>   * registers like cr3 on the i386
>   */
>  
> -extern volatile DEFINE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
> +DECLARE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
>  
>  static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
>  {

Yes volatile sucks, but might this break something?

Whether the volatile is actually needed or not, it's bad to have this
kind of potential behavior changing nugget hidden in this seemingly
inocuous change.  Especially if you're the poor soul who ends up
having to debug it :-/

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Re: [PATCH 3/7] percpu: clean up percpu variable definitions

[Tejun Heo]

David Miller wrote:
> From: Tejun Heo <tj@kernel.org>
> Date: Mon,  1 Jun 2009 17:58:24 +0900
> 
>> --- a/arch/cris/include/asm/mmu_context.h
>> +++ b/arch/cris/include/asm/mmu_context.h
>> @@ -17,7 +17,7 @@ extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
>>   * registers like cr3 on the i386
>>   */
>>  
>> -extern volatile DEFINE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
>> +DECLARE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
>>  
>>  static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
>>  {
> 
> Yes volatile sucks, but might this break something?
> 
> Whether the volatile is actually needed or not, it's bad to have this
> kind of potential behavior changing nugget hidden in this seemingly
> inocuous change.  Especially if you're the poor soul who ends up
> having to debug it :-/

You're right.  Aieee... how do I feed volatile to the DEFINE macro.
I'll think of something.

Thanks.

-- 
tejun

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Re: [PATCH 3/7] percpu: clean up percpu variable definitions

[Benjamin Herrenschmidt]

On Mon, 2009-06-01 at 20:36 +0900, Tejun Heo wrote:
> > Whether the volatile is actually needed or not, it's bad to have this
> > kind of potential behavior changing nugget hidden in this seemingly
> > inocuous change.  Especially if you're the poor soul who ends up
> > having to debug it :-/
> 
> You're right.  Aieee... how do I feed volatile to the DEFINE macro.
> I'll think of something.

Or better, work with the cris maintainer to figure out whether it's
needed (it probably isn't) and have a pre-requisite patch that removes
it before your series :-)

Cheers,
Ben.


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Re: [PATCH 3/7] percpu: clean up percpu variable definitions

[Tejun Heo]

Benjamin Herrenschmidt wrote:
> On Mon, 2009-06-01 at 20:36 +0900, Tejun Heo wrote:
>>> Whether the volatile is actually needed or not, it's bad to have this
>>> kind of potential behavior changing nugget hidden in this seemingly
>>> inocuous change.  Especially if you're the poor soul who ends up
>>> having to debug it :-/
>> You're right.  Aieee... how do I feed volatile to the DEFINE macro.
>> I'll think of something.
> 
> Or better, work with the cris maintainer to figure out whether it's
> needed (it probably isn't) and have a pre-requisite patch that removes
> it before your series :-)

Yeap, that's worth giving a shot.

Mikael Starvik, can you please enlighten us why volatile is necessary
there?

Thanks.

-- 
tejun

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Re: [PATCH 3/7] percpu: clean up percpu variable definitions

[Jesper Nilsson]

On Fri, Jun 05, 2009 at 06:25:30AM +0200, Tejun Heo wrote:
> Benjamin Herrenschmidt wrote:
> > On Mon, 2009-06-01 at 20:36 +0900, Tejun Heo wrote:
> >>> Whether the volatile is actually needed or not, it's bad to have this
> >>> kind of potential behavior changing nugget hidden in this seemingly
> >>> inocuous change.  Especially if you're the poor soul who ends up
> >>> having to debug it :-/
> >> You're right.  Aieee... how do I feed volatile to the DEFINE macro.
> >> I'll think of something.
> > 
> > Or better, work with the cris maintainer to figure out whether it's
> > needed (it probably isn't) and have a pre-requisite patch that removes
> > it before your series :-)
> 
> Yeap, that's worth giving a shot.
> 
> Mikael Starvik, can you please enlighten us why volatile is necessary
> there?

I've talked with Mikael, and we both agreed that this was probably
a legacy from earlier versions, and the volatile is no longer needed.

Confirmed by booting and running some video-streaming on an ARTPEC-3
(CRISv32) board.

You can take the following patch as a pre-requisite, or go the way of
the original patch.

From: Jesper Nilsson <jesper.nilsson@axis.com>
Subject: [PATCH] CRIS: Change DEFINE_PER_CPU of current_pgd to be non volatile.

The DEFINE_PER_CPU of current_pgd was on CRIS defined using volatile,
which is not needed. Remove volatile.

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
---
 arch/cris/include/asm/mmu_context.h |    3 ++-
 arch/cris/mm/fault.c                |    2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/cris/include/asm/mmu_context.h b/arch/cris/include/asm/mmu_context.h
index 72ba08d..476cd9e 100644
--- a/arch/cris/include/asm/mmu_context.h
+++ b/arch/cris/include/asm/mmu_context.h
@@ -17,7 +17,8 @@ extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
  * registers like cr3 on the i386
  */
 
-extern volatile DEFINE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
+/* defined in arch/cris/mm/fault.c */
+extern DEFINE_PER_CPU(pgd_t *, current_pgd);
 
 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 {
diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c
index c4c76db..84d22ae 100644
--- a/arch/cris/mm/fault.c
+++ b/arch/cris/mm/fault.c
@@ -29,7 +29,7 @@ extern void die_if_kernel(const char *, struct pt_regs *, long);
 
 /* current active page directory */
 
-volatile DEFINE_PER_CPU(pgd_t *,current_pgd);
+DEFINE_PER_CPU(pgd_t *, current_pgd);
 unsigned long cris_signal_return_page;
 
 /*
-- 
1.6.1

> Thanks.
> 
> -- 
> tejun

/^JN - Jesper Nilsson
-- 
               Jesper Nilsson -- jesper.nilsson@axis.com

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Re: [PATCH 3/7] percpu: clean up percpu variable definitions

[Tejun Heo]

Hello,

Jesper Nilsson wrote:
> I've talked with Mikael, and we both agreed that this was probably
> a legacy from earlier versions, and the volatile is no longer needed.
> 
> Confirmed by booting and running some video-streaming on an ARTPEC-3
> (CRISv32) board.
> 
> You can take the following patch as a pre-requisite, or go the way of
> the original patch.
> 
> From: Jesper Nilsson <jesper.nilsson@axis.com>
> Subject: [PATCH] CRIS: Change DEFINE_PER_CPU of current_pgd to be non volatile.
> 
> The DEFINE_PER_CPU of current_pgd was on CRIS defined using volatile,
> which is not needed. Remove volatile.
> 
> Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>

Super.  Included in the series.

Thanks a lot.

-- 
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Re: [PATCH 3/7] percpu: clean up percpu variable definitions

[H. Peter Anvin]

David Miller wrote:
> From: Tejun Heo <tj@kernel.org>
> Date: Mon,  1 Jun 2009 17:58:24 +0900
> 
>> --- a/arch/cris/include/asm/mmu_context.h
>> +++ b/arch/cris/include/asm/mmu_context.h
>> @@ -17,7 +17,7 @@ extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
>>   * registers like cr3 on the i386
>>   */
>>  
>> -extern volatile DEFINE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
>> +DECLARE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
>>  
>>  static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
>>  {
> 
> Yes volatile sucks, but might this break something?
> 
> Whether the volatile is actually needed or not, it's bad to have this
> kind of potential behavior changing nugget hidden in this seemingly
> inocuous change.  Especially if you're the poor soul who ends up
> having to debug it :-/

Shouldn't the "volatile" go inside the DECLARE_PER_CPU() with the rest
of the type?  [Disclaimer: I haven't actually looked.]

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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