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| author | Linus Walleij <linus.walleij@linaro.org> | 2019-04-08 13:03:09 +0200 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2019-04-08 13:03:09 +0200 |
| commit | 26af34079f1d8299932303cfd2b376b9cf55a35c (patch) | |
| tree | f1a9824855fae569aa51c2109a5929715143093d /lib/sbitmap.c | |
| parent | 27157af66324d529b43231c12b5d1e1a3e9fa620 (diff) | |
| parent | 79a3aaa7b82e3106be97842dedfd8429248896e6 (diff) | |
Merge tag 'v5.1-rc3' into devel
Linux 5.1-rc3
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); /* |