diff options
| author | Uros Bizjak <ubizjak@gmail.com> | 2024-05-23 11:19:26 +0200 |
|---|---|---|
| committer | Kent Overstreet <kent.overstreet@linux.dev> | 2024-07-14 19:00:12 -0400 |
| commit | 68573b936d3fceda9cd5cce3a577e035d19ad426 (patch) | |
| tree | 872f291bf9b8d6f439c9d0a5bd372d42557e8e6b /fs/bcachefs/buckets.h | |
| parent | e76a2b65b0565f55ea668ec46d54f6a00b8ea9fc (diff) | |
bcachefs: Use try_cmpxchg() family of functions instead of cmpxchg()
Use try_cmpxchg() family of functions instead of
cmpxchg (*ptr, old, new) == old. x86 CMPXCHG instruction returns
success in ZF flag, so this change saves a compare after cmpxchg
(and related move instruction in front of cmpxchg).
Also, try_cmpxchg() implicitly assigns old *ptr value to "old" when
cmpxchg fails. There is no need to re-read the value in the loop.
No functional change intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'fs/bcachefs/buckets.h')
| -rw-r--r-- | fs/bcachefs/buckets.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/bcachefs/buckets.h b/fs/bcachefs/buckets.h index 8ad4be73860c..05a1c98754f2 100644 --- a/fs/bcachefs/buckets.h +++ b/fs/bcachefs/buckets.h @@ -432,13 +432,13 @@ static inline int bch2_disk_reservation_add(struct bch_fs *c, struct disk_reserv #ifdef __KERNEL__ u64 old, new; + old = this_cpu_read(c->pcpu->sectors_available); do { - old = this_cpu_read(c->pcpu->sectors_available); if (sectors > old) return __bch2_disk_reservation_add(c, res, sectors, flags); new = old - sectors; - } while (this_cpu_cmpxchg(c->pcpu->sectors_available, old, new) != old); + } while (!this_cpu_try_cmpxchg(c->pcpu->sectors_available, &old, new)); this_cpu_add(*c->online_reserved, sectors); res->sectors += sectors; |