percpu_ida: Make percpu_ida_alloc + callers accept task state bitmask

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>

1 files changed, 4 insertions, 2 deletions

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index d64a02fb1f73..5d70edc9855f 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -36,7 +36,8 @@ static unsigned int __blk_mq_get_tag(struct blk_mq_tags *tags, gfp_t gfp)
 {
         int tag;
 
-        tag = percpu_ida_alloc(&tags->free_tags, gfp);
+        tag = percpu_ida_alloc(&tags->free_tags, (gfp & __GFP_WAIT) ?
+                               TASK_UNINTERRUPTIBLE : TASK_RUNNING);
         if (tag < 0)
                 return BLK_MQ_TAG_FAIL;
         return tag + tags->nr_reserved_tags;
@@ -52,7 +53,8 @@ static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_tags *tags,
                 return BLK_MQ_TAG_FAIL;
         }
 
-        tag = percpu_ida_alloc(&tags->reserved_tags, gfp);
+        tag = percpu_ida_alloc(&tags->reserved_tags, (gfp & __GFP_WAIT) ?
+                               TASK_UNINTERRUPTIBLE : TASK_RUNNING);
         if (tag < 0)
                 return BLK_MQ_TAG_FAIL;
         return tag;