From: Luis Chamberlain <mcgrof@kernel.org>
To: david@redhat.com, patches@lists.linux.dev,
linux-modules@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, pmladek@suse.com,
petr.pavlu@suse.com, prarit@redhat.com,
torvalds@linux-foundation.org, gregkh@linuxfoundation.org,
rafael@kernel.org
Cc: christophe.leroy@csgroup.eu, tglx@linutronix.de,
peterz@infradead.org, song@kernel.org, rppt@kernel.org,
dave@stgolabs.net, willy@infradead.org, vbabka@suse.cz,
mhocko@suse.com, dave.hansen@linux.intel.com,
colin.i.king@gmail.com, jim.cromie@gmail.com,
catalin.marinas@arm.com, jbaron@akamai.com,
rick.p.edgecombe@intel.com, mcgrof@kernel.org
Subject: [PATCH v3 1/2] Change DEFINE_SEMAPHORE() to take a number argument
Date: Thu, 13 Apr 2023 22:13:48 -0700 [thread overview]
Message-ID: <20230414051349.1986744-2-mcgrof@kernel.org> (raw)
In-Reply-To: <20230414051349.1986744-1-mcgrof@kernel.org>
From: Peter Zijlstra <peterz@infradead.org>
Fundamentally semaphores are a counted primitive, but
DEFINE_SEMAPHORE() does not expose this and explicitly creates a
binary semaphore.
Change DEFINE_SEMAPHORE() to take a number argument and use that in the
few places that open-coded it using __SEMAPHORE_INITIALIZER().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[mcgrof: add some tribal knowledge about why some folks prefer
binary sempahores over mutexes]
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
arch/mips/cavium-octeon/setup.c | 2 +-
arch/x86/kernel/cpu/intel.c | 2 +-
drivers/firmware/efi/runtime-wrappers.c | 2 +-
drivers/firmware/efi/vars.c | 2 +-
drivers/macintosh/adb.c | 2 +-
drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c | 2 +-
drivers/platform/x86/intel/ifs/sysfs.c | 2 +-
drivers/scsi/esas2r/esas2r_ioctl.c | 2 +-
.../vc04_services/interface/vchiq_arm/vchiq_arm.c | 2 +-
include/linux/semaphore.h | 11 +++++++++--
kernel/printk/printk.c | 2 +-
net/rxrpc/call_object.c | 6 ++----
12 files changed, 21 insertions(+), 16 deletions(-)
diff --git a/arch/mips/cavium-octeon/setup.c b/arch/mips/cavium-octeon/setup.c
index a71727f7a608..c5561016f577 100644
--- a/arch/mips/cavium-octeon/setup.c
+++ b/arch/mips/cavium-octeon/setup.c
@@ -72,7 +72,7 @@ extern void pci_console_init(const char *arg);
static unsigned long long max_memory = ULLONG_MAX;
static unsigned long long reserve_low_mem;
-DEFINE_SEMAPHORE(octeon_bootbus_sem);
+DEFINE_SEMAPHORE(octeon_bootbus_sem, 1);
EXPORT_SYMBOL(octeon_bootbus_sem);
static struct octeon_boot_descriptor *octeon_boot_desc_ptr;
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 291d4167fab8..12bad63822f0 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -1177,7 +1177,7 @@ static const struct {
static struct ratelimit_state bld_ratelimit;
static unsigned int sysctl_sld_mitigate = 1;
-static DEFINE_SEMAPHORE(buslock_sem);
+static DEFINE_SEMAPHORE(buslock_sem, 1);
#ifdef CONFIG_PROC_SYSCTL
static struct ctl_table sld_sysctls[] = {
diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
index 1fba4e09cdcf..a400c4312c82 100644
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -158,7 +158,7 @@ void efi_call_virt_check_flags(unsigned long flags, const char *call)
* none of the remaining functions are actually ever called at runtime.
* So let's just use a single lock to serialize all Runtime Services calls.
*/
-static DEFINE_SEMAPHORE(efi_runtime_lock);
+static DEFINE_SEMAPHORE(efi_runtime_lock, 1);
/*
* Expose the EFI runtime lock to the UV platform
diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c
index bd75b87f5fc1..bfc5fa6aa47b 100644
--- a/drivers/firmware/efi/vars.c
+++ b/drivers/firmware/efi/vars.c
@@ -21,7 +21,7 @@
/* Private pointer to registered efivars */
static struct efivars *__efivars;
-static DEFINE_SEMAPHORE(efivars_lock);
+static DEFINE_SEMAPHORE(efivars_lock, 1);
static efi_status_t check_var_size(bool nonblocking, u32 attributes,
unsigned long size)
diff --git a/drivers/macintosh/adb.c b/drivers/macintosh/adb.c
index 23bd0c77ac1a..56599515d51a 100644
--- a/drivers/macintosh/adb.c
+++ b/drivers/macintosh/adb.c
@@ -80,7 +80,7 @@ static struct adb_driver *adb_controller;
BLOCKING_NOTIFIER_HEAD(adb_client_list);
static int adb_got_sleep;
static int adb_inited;
-static DEFINE_SEMAPHORE(adb_probe_mutex);
+static DEFINE_SEMAPHORE(adb_probe_mutex, 1);
static int sleepy_trackpad;
static int autopoll_devs;
int __adb_probe_sync;
diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
index 5d1e4fe335aa..5a105bab4387 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
@@ -298,7 +298,7 @@ const u32 dmae_reg_go_c[] = {
/* Global resources for unloading a previously loaded device */
#define BNX2X_PREV_WAIT_NEEDED 1
-static DEFINE_SEMAPHORE(bnx2x_prev_sem);
+static DEFINE_SEMAPHORE(bnx2x_prev_sem, 1);
static LIST_HEAD(bnx2x_prev_list);
/* Forward declaration */
diff --git a/drivers/platform/x86/intel/ifs/sysfs.c b/drivers/platform/x86/intel/ifs/sysfs.c
index ee636a76b083..4c3c642ee19a 100644
--- a/drivers/platform/x86/intel/ifs/sysfs.c
+++ b/drivers/platform/x86/intel/ifs/sysfs.c
@@ -13,7 +13,7 @@
* Protects against simultaneous tests on multiple cores, or
* reloading can file while a test is in progress
*/
-static DEFINE_SEMAPHORE(ifs_sem);
+static DEFINE_SEMAPHORE(ifs_sem, 1);
/*
* The sysfs interface to check additional details of last test
diff --git a/drivers/scsi/esas2r/esas2r_ioctl.c b/drivers/scsi/esas2r/esas2r_ioctl.c
index e003d923acbf..055d2e87a2c8 100644
--- a/drivers/scsi/esas2r/esas2r_ioctl.c
+++ b/drivers/scsi/esas2r/esas2r_ioctl.c
@@ -56,7 +56,7 @@ dma_addr_t esas2r_buffered_ioctl_addr;
u32 esas2r_buffered_ioctl_size;
struct pci_dev *esas2r_buffered_ioctl_pcid;
-static DEFINE_SEMAPHORE(buffered_ioctl_semaphore);
+static DEFINE_SEMAPHORE(buffered_ioctl_semaphore, 1);
typedef int (*BUFFERED_IOCTL_CALLBACK)(struct esas2r_adapter *,
struct esas2r_request *,
struct esas2r_sg_context *,
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index cddcd3c596c9..1a656fdc9445 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -149,7 +149,7 @@ static char *g_fragments_base;
static char *g_free_fragments;
static struct semaphore g_free_fragments_sema;
-static DEFINE_SEMAPHORE(g_free_fragments_mutex);
+static DEFINE_SEMAPHORE(g_free_fragments_mutex, 1);
static int
vchiq_blocking_bulk_transfer(struct vchiq_instance *instance, unsigned int handle, void *data,
diff --git a/include/linux/semaphore.h b/include/linux/semaphore.h
index 6694d0019a68..2d6aa3fd7861 100644
--- a/include/linux/semaphore.h
+++ b/include/linux/semaphore.h
@@ -25,8 +25,15 @@ struct semaphore {
.wait_list = LIST_HEAD_INIT((name).wait_list), \
}
-#define DEFINE_SEMAPHORE(name) \
- struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)
+/*
+ * There is a big difference between a binary semaphore and a mutex.
+ * You cannot call mutex_unlock() from IRQ context because it takes an
+ * internal mutex spin_lock in a non-IRQ-safe manner. Both try_lock()
+ * and unlock() can be called from IRQ context. A mutex must also be
+ * released in the same context that locked it.
+ */
+#define DEFINE_SEMAPHORE(_name, _n) \
+ struct semaphore _name = __SEMAPHORE_INITIALIZER(_name, _n)
static inline void sema_init(struct semaphore *sem, int val)
{
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index fd0c9f913940..76987aaa5a45 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -89,7 +89,7 @@ static DEFINE_MUTEX(console_mutex);
* console_sem protects updates to console->seq and console_suspended,
* and also provides serialization for console printing.
*/
-static DEFINE_SEMAPHORE(console_sem);
+static DEFINE_SEMAPHORE(console_sem, 1);
HLIST_HEAD(console_list);
EXPORT_SYMBOL_GPL(console_list);
DEFINE_STATIC_SRCU(console_srcu);
diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index e9f1f49d18c2..3e5cc70884dd 100644
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -40,10 +40,8 @@ const char *const rxrpc_call_completions[NR__RXRPC_CALL_COMPLETIONS] = {
struct kmem_cache *rxrpc_call_jar;
-static struct semaphore rxrpc_call_limiter =
- __SEMAPHORE_INITIALIZER(rxrpc_call_limiter, 1000);
-static struct semaphore rxrpc_kernel_call_limiter =
- __SEMAPHORE_INITIALIZER(rxrpc_kernel_call_limiter, 1000);
+static DEFINE_SEMAPHORE(rxrpc_call_limiter, 1000);
+static DEFINE_SEMAPHORE(rxrpc_kernel_call_limiter, 1000);
void rxrpc_poke_call(struct rxrpc_call *call, enum rxrpc_call_poke_trace what)
{
--
2.39.2
next prev parent reply other threads:[~2023-04-14 5:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-14 5:13 [PATCH v3 0/2] modules/kmod: replace implementation with a sempahore Luis Chamberlain
2023-04-14 5:13 ` Luis Chamberlain [this message]
2023-04-14 17:10 ` [PATCH v3 1/2] Change DEFINE_SEMAPHORE() to take a number argument Luis Chamberlain
2023-04-14 5:13 ` [PATCH v3 2/2] modules/kmod: replace implementation with a semaphore Luis Chamberlain
2023-04-14 9:34 ` Miroslav Benes
2023-04-14 9:37 ` David Hildenbrand
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230414051349.1986744-2-mcgrof@kernel.org \
--to=mcgrof@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=christophe.leroy@csgroup.eu \
--cc=colin.i.king@gmail.com \
--cc=dave.hansen@linux.intel.com \
--cc=dave@stgolabs.net \
--cc=david@redhat.com \
--cc=gregkh@linuxfoundation.org \
--cc=jbaron@akamai.com \
--cc=jim.cromie@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-modules@vger.kernel.org \
--cc=mhocko@suse.com \
--cc=patches@lists.linux.dev \
--cc=peterz@infradead.org \
--cc=petr.pavlu@suse.com \
--cc=pmladek@suse.com \
--cc=prarit@redhat.com \
--cc=rafael@kernel.org \
--cc=rick.p.edgecombe@intel.com \
--cc=rppt@kernel.org \
--cc=song@kernel.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=vbabka@suse.cz \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox