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| author | Mark Brown <broonie@kernel.org> | 2019-04-02 16:20:47 +0700 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2019-04-02 16:20:47 +0700 |
| commit | 6d5e2bf9d203e4d9e08ca2e9420c6ff22ad190af (patch) | |
| tree | c2c20648773d3326f942e34ef73b06566f7a19ec /lib/sbitmap.c | |
| parent | b820d52e7eed7b30b2dfef5f4213a2bc3cbea6f3 (diff) | |
| parent | 257f9053c0204ea47491aa236004fd1226f75fa8 (diff) | |
Merge branch 'acpi-utils' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm into asoc-5.2
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); /* |