From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oren Laadan Subject: [C/R v20][PATCH 01/96] eclone (1/11): Factor out code to allocate pidmap page Date: Wed, 17 Mar 2010 12:07:49 -0400 Message-ID: <1268842164-5590-2-git-send-email-orenl@cs.columbia.edu> References: <1268842164-5590-1-git-send-email-orenl@cs.columbia.edu> Return-path: In-Reply-To: <1268842164-5590-1-git-send-email-orenl@cs.columbia.edu> Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, Serge Hallyn , Ingo Molnar , containers@lists.linux-foundation.org, Sukadev Bhattiprolu List-Id: linux-api@vger.kernel.org From: Sukadev Bhattiprolu To simplify alloc_pidmap(), move code to allocate a pid map page to a separate function. Changelog[v4]: - [Oren Laadan] Adapt to kernel 2.6.33-rc5 Changelog[v3]: - Earlier version of patchset called alloc_pidmap_page() from two places. But now its called from only one place. Even so, moving this code out into a separate function simplifies alloc_pidmap(). Changelog[v2]: - (Matt Helsley, Dave Hansen) Have alloc_pidmap_page() return -ENOMEM on error instead of -1. Signed-off-by: Sukadev Bhattiprolu Acked-by: Serge E. Hallyn Tested-by: Serge E. Hallyn Reviewed-by: Oren Laadan --- kernel/pid.c | 41 ++++++++++++++++++++++++++--------------- 1 files changed, 26 insertions(+), 15 deletions(-) diff --git a/kernel/pid.c b/kernel/pid.c index 2e17c9c..39292e6 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -122,6 +122,30 @@ static void free_pidmap(struct upid *upid) atomic_inc(&map->nr_free); } +static int alloc_pidmap_page(struct pidmap *map) +{ + void *page; + + if (likely(map->page)) + return 0; + + page = kzalloc(PAGE_SIZE, GFP_KERNEL); + /* + * Free the page if someone raced with us installing it: + */ + spin_lock_irq(&pidmap_lock); + if (!map->page) { + map->page = page; + page = NULL; + } + spin_unlock_irq(&pidmap_lock); + kfree(page); + if (unlikely(!map->page)) + return -1; + + return 0; +} + static int alloc_pidmap(struct pid_namespace *pid_ns) { int i, offset, max_scan, pid, last = pid_ns->last_pid; @@ -134,22 +158,9 @@ static int alloc_pidmap(struct pid_namespace *pid_ns) map = &pid_ns->pidmap[pid/BITS_PER_PAGE]; max_scan = (pid_max + BITS_PER_PAGE - 1)/BITS_PER_PAGE - !offset; for (i = 0; i <= max_scan; ++i) { - if (unlikely(!map->page)) { - void *page = kzalloc(PAGE_SIZE, GFP_KERNEL); - /* - * Free the page if someone raced with us - * installing it: - */ - spin_lock_irq(&pidmap_lock); - if (!map->page) { - map->page = page; - page = NULL; - } - spin_unlock_irq(&pidmap_lock); - kfree(page); - if (unlikely(!map->page)) + if (unlikely(!map->page)) + if (alloc_pidmap_page(map) < 0) break; - } if (likely(atomic_read(&map->nr_free))) { do { if (!test_and_set_bit(offset, map->page)) { -- 1.6.3.3 -- 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