From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx201.postini.com [74.125.245.201]) by kanga.kvack.org (Postfix) with SMTP id 875F46B0031 for ; Thu, 25 Jul 2013 05:35:37 -0400 (EDT) Date: Thu, 25 Jul 2013 11:35:31 +0200 From: Jan Kara Subject: Re: [PATCH v2] lib: Make radix_tree_node_alloc() work correctly within interrupt Message-ID: <20130725093531.GA9388@quack.suse.cz> References: <1374617060-25805-1-git-send-email-jack@suse.cz> <51EEFFAD.701@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51EEFFAD.701@infradead.org> Sender: owner-linux-mm@kvack.org List-ID: To: Randy Dunlap Cc: Jan Kara , Andrew Morton , LKML , linux-mm@kvack.org, Jens Axboe On Tue 23-07-13 15:11:57, Randy Dunlap wrote: > On 07/23/13 15:04, Jan Kara wrote: > s/sence/sense/ please. Thanks. I keep getting this wrong... I've updated the patch locally but I won't resend it just for this spellcheck fix (yet). Honza > > diff --git a/lib/radix-tree.c b/lib/radix-tree.c > > index e796429..7811ed3 100644 > > --- a/lib/radix-tree.c > > +++ b/lib/radix-tree.c > > @@ -32,6 +32,7 @@ > > #include > > #include > > #include > > +#include /* in_interrupt() */ > > > > > > #ifdef __KERNEL__ > > @@ -207,7 +208,12 @@ radix_tree_node_alloc(struct radix_tree_root *root) > > struct radix_tree_node *ret = NULL; > > gfp_t gfp_mask = root_gfp_mask(root); > > > > - if (!(gfp_mask & __GFP_WAIT)) { > > + /* > > + * Preload code isn't irq safe and it doesn't make sence to use > > sense > > > + * preloading in the interrupt anyway as all the allocations have to > > + * be atomic. So just do normal allocation when in interrupt. > > + */ > > + if (!(gfp_mask & __GFP_WAIT) && !in_interrupt()) { > > struct radix_tree_preload *rtp; > > > > /* > > @@ -264,7 +270,7 @@ radix_tree_node_free(struct radix_tree_node *node) > > * To make use of this facility, the radix tree must be initialised without > > * __GFP_WAIT being passed to INIT_RADIX_TREE(). > > */ > > -int radix_tree_preload(gfp_t gfp_mask) > > +static int __radix_tree_preload(gfp_t gfp_mask) > > { > > struct radix_tree_preload *rtp; > > struct radix_tree_node *node; > > @@ -288,9 +294,40 @@ int radix_tree_preload(gfp_t gfp_mask) > > out: > > return ret; > > } > > + > > +/* > > + * Load up this CPU's radix_tree_node buffer with sufficient objects to > > + * ensure that the addition of a single element in the tree cannot fail. On > > + * success, return zero, with preemption disabled. On error, return -ENOMEM > > + * with preemption not disabled. > > + * > > + * To make use of this facility, the radix tree must be initialised without > > + * __GFP_WAIT being passed to INIT_RADIX_TREE(). > > + */ > > +int radix_tree_preload(gfp_t gfp_mask) > > +{ > > + /* Warn on non-sensical use... */ > > + WARN_ON_ONCE(!(gfp_mask & __GFP_WAIT)); > > + return __radix_tree_preload(gfp_mask); > > +} > > EXPORT_SYMBOL(radix_tree_preload); > > > > /* > > + * The same as above function, except we don't guarantee preloading happens. > > + * We do it, if we decide it helps. On success, return zero with preemption > > + * disabled. On error, return -ENOMEM with preemption not disabled. > > + */ > > +int radix_tree_maybe_preload(gfp_t gfp_mask) > > +{ > > + if (gfp_mask & __GFP_WAIT) > > + return __radix_tree_preload(gfp_mask); > > + /* Preloading doesn't help anything with this gfp mask, skip it */ > > + preempt_disable(); > > + return 0; > > +} > > +EXPORT_SYMBOL(radix_tree_maybe_preload); > > + > > +/* > > * Return the maximum key which can be store into a > > stored > > > * radix tree with height HEIGHT. > > */ > > -- > ~Randy -- Jan Kara SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org