Cc LKML
Sukadev Bhattiprolu [sukadev@xxxxxxxxxxxxxxxxxx] 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 <sukadev@xxxxxxxxxxxxxxxxxx>
| Acked-by: Serge Hallyn <serue@xxxxxxxxxx>
| Reviewed-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
| ---
| 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
|
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