diff options
| author | Wolfram Sang <wsa@the-dreams.de> | 2019-05-03 15:20:04 +0200 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2019-05-03 15:20:58 +0200 |
| commit | d00afd5ede1c29a6dc59be2d7fb7d6ef28eb85c5 (patch) | |
| tree | e194b1968e54380a6654abf7d3a037ca0a010280 /lib/sbitmap.c | |
| parent | 9a51b86a61214a297cdfc1bb705b7267f9455ae6 (diff) | |
| parent | d5984d2a312144bedccf32aea2298f8df05bb617 (diff) | |
Merge branch 'i2c-mux/for-next' of https://github.com/peda-r/i2c-mux into i2c/for-5.2
Mainly some pca954x work, i.e. removal of unused platform data support
and added support for sysfs interface for manipulating/examining the
idle state. And then a mechanical cocci-style patch.
Diffstat (limited to 'lib/sbitmap.c')
| -rw-r--r-- | lib/sbitmap.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/lib/sbitmap.c b/lib/sbitmap.c index 5b382c1244ed..155fe38756ec 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -591,6 +591,17 @@ EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up); void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr, unsigned int cpu) { + /* + * Once the clear bit is set, the bit may be allocated out. + * + * Orders READ/WRITE on the asssociated instance(such as request + * of blk_mq) by this bit for avoiding race with re-allocation, + * and its pair is the memory barrier implied in __sbitmap_get_word. + * + * One invariant is that the clear bit has to be zero when the bit + * is in use. + */ + smp_mb__before_atomic(); sbitmap_deferred_clear_bit(&sbq->sb, nr); /* |