From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sukadev Bhattiprolu Subject: Re: [v12][PATCH 1/9] Factor out code to allocate pidmap page Date: Wed, 11 Nov 2009 14:38:49 -0800 Message-ID: <20091111223849.GB24988@suka> References: <20091111043440.GA9377@suka> <20091111044250.GA11393@suka> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20091111044250.GA11393@suka> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Andrew Morton Cc: mtk.manpages-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, Containers , Nathan Lynch , matthltc-npbjlsIvGkV82hYKe6nXyg@public.gmane.org, "Eric W. Biederman" , hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Alexey Dobriyan , roland-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, Pavel Emelyanov , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org Cc LKML Sukadev Bhattiprolu [sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org] wrote: | | Subject: [v12][PATCH 1/9] 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 | Acked-by: Serge Hallyn | Reviewed-by: Oren Laadan | --- | kernel/pid.c | 45 ++++++++++++++++++++++++++++++--------------- | 1 files changed, 30 insertions(+), 15 deletions(-) | | diff --git a/kernel/pid.c b/kernel/pid.c | index d3f722d..7d4bb6e 100644 | --- a/kernel/pid.c | +++ b/kernel/pid.c | @@ -122,9 +122,35 @@ 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) | + 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 @@ 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) | - 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)) { | -- | 1.6.0.4 | | _______________________________________________ | Containers mailing list | Containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org | https://lists.linux-foundation.org/mailman/listinfo/containers