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percpu_ida: Make percpu_ida_alloc + callers accept task state bitmask

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This patch changes percpu_ida_alloc() + callers to accept task state
bitmask for prepare_to_wait() for code like target/iscsi that needs
it for interruptible sleep, that is provided in a subsequent patch.

It now expects TASK_UNINTERRUPTIBLE when the caller is able to sleep
waiting for a new tag, or TASK_RUNNING when the caller cannot sleep,
and is forced to return a negative value when no tags are available.

v2 changes:
  - Include blk-mq + tcm_fc + vhost/scsi + target/iscsi changes
  - Drop signal_pending_state() call
v3 changes:
  - Only call prepare_to_wait() + finish_wait() when != TASK_RUNNING
    (PeterZ)

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: <stable@vger.kernel.org> #3.12+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Kent Overstreet
2014-01-19 08:26:37 +00:00
committed by Nicholas Bellinger
parent 4a4caa29f1
commit 6f6b5d1ec5
6 changed files with 23 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
lib/percpu_ida.c
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@@ -132,22 +132,22 @@ static inline unsigned alloc_local_tag(struct percpu_ida_cpu *tags)
/**
* percpu_ida_alloc - allocate a tag
* @pool: pool to allocate from
* @gfp: gfp flags
* @state: task state for prepare_to_wait
*
* Returns a tag - an integer in the range [0..nr_tags) (passed to
* tag_pool_init()), or otherwise -ENOSPC on allocation failure.
*
* Safe to be called from interrupt context (assuming it isn't passed
* __GFP_WAIT, of course).
* TASK_UNINTERRUPTIBLE, of course).
*
* @gfp indicates whether or not to wait until a free id is available (it's not
* used for internal memory allocations); thus if passed __GFP_WAIT we may sleep
* however long it takes until another thread frees an id (same semantics as a
* mempool).
*
* Will not fail if passed __GFP_WAIT.
* Will not fail if passed TASK_UNINTERRUPTIBLE.
*/
int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp)
int percpu_ida_alloc(struct percpu_ida *pool, int state)
{
DEFINE_WAIT(wait);
struct percpu_ida_cpu *tags;
@@ -174,7 +174,8 @@ int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp)
*
* global lock held and irqs disabled, don't need percpu lock
*/
prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
if (state != TASK_RUNNING)
prepare_to_wait(&pool->wait, &wait, state);
if (!tags->nr_free)
alloc_global_tags(pool, tags);
@@ -191,7 +192,7 @@ int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp)
spin_unlock(&pool->lock);
local_irq_restore(flags);
if (tag >= 0 || !(gfp & __GFP_WAIT))
if (tag >= 0 || state == TASK_RUNNING)
break;
schedule();
@@ -199,8 +200,9 @@ int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp)
local_irq_save(flags);
tags = this_cpu_ptr(pool->tag_cpu);
}
if (state != TASK_RUNNING)
finish_wait(&pool->wait, &wait);
finish_wait(&pool->wait, &wait);
return tag;
}
EXPORT_SYMBOL_GPL(percpu_ida_alloc);