Messages in this thread Patch in this message | | | Date | Mon, 7 Sep 2009 14:13:58 -0700 | From | Sukadev Bhattiprolu <> | Subject | [RFC][v5][PATCH 1/8]: Factor out code to allocate pidmap page |
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Subject: [RFC][v5][PATCH 1/8]: Factor out code to allocate pidmap page
To simplify alloc_pidmap(), move code to allocate a pid map page to a separate function.
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 <sukadev@linux.vnet.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Reviewed-by: Oren Laadan <orenl@cs.columbia.edu> --- kernel/pid.c | 46 ++++++++++++++++++++++++++++++---------------- 1 files changed, 30 insertions(+), 16 deletions(-)
Index: linux-2.6/kernel/pid.c =================================================================== --- linux-2.6.orig/kernel/pid.c 2009-09-07 13:08:50.000000000 -0700 +++ linux-2.6/kernel/pid.c 2009-09-07 13:11:30.000000000 -0700 @@ -122,9 +122,35 @@ 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) + kfree(page); + else + map->page = page; + spin_unlock_irq(&pidmap_lock); + + if (unlikely(!map->page)) + return -ENOMEM; + + return 0; +} + static int alloc_pidmap(struct pid_namespace *pid_ns) { int i, offset, max_scan, pid, last = pid_ns->last_pid; + int rc; struct pidmap *map; pid = last + 1; @@ -134,21 +160,10 @@ 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) - kfree(page); - else - map->page = page; - spin_unlock_irq(&pidmap_lock); - if (unlikely(!map->page)) - break; - } + rc = alloc_pidmap_page(map); + if (rc) + break; + if (likely(atomic_read(&map->nr_free))) { do { if (!test_and_set_bit(offset, map->page)) {
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