diff options
| author | Uros Bizjak <ubizjak@gmail.com> | 2024-09-23 14:22:17 +0200 |
|---|---|---|
| committer | Carlos Maiolino <cem@kernel.org> | 2024-10-07 08:00:11 +0200 |
| commit | 20195d011c840b01fa91a85ebcd099ca95fbf8fc (patch) | |
| tree | 1e9f0af89a9089da333eb0e353eb775fe35772bb /fs/xfs | |
| parent | 6148b77960cc43547e4b819bfa5f064fb83dc2ae (diff) | |
xfs: Use try_cmpxchg() in xlog_cil_insert_pcp_aggregate()
Use !try_cmpxchg instead of cmpxchg (*ptr, old, new) != old in
xlog_cil_insert_pcp_aggregate(). x86 CMPXCHG instruction returns
success in ZF flag, so this change saves a compare after 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.
Note that the value from *ptr should be read using READ_ONCE to
prevent the compiler from merging, refetching or reordering the read.
No functional change intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Cc: Chandan Babu R <chandan.babu@oracle.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Diffstat (limited to 'fs/xfs')
| -rw-r--r-- | fs/xfs/xfs_log_cil.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c index 391a938d690c..80da0cf87d7a 100644 --- a/fs/xfs/xfs_log_cil.c +++ b/fs/xfs/xfs_log_cil.c @@ -156,7 +156,6 @@ xlog_cil_insert_pcp_aggregate( struct xfs_cil *cil, struct xfs_cil_ctx *ctx) { - struct xlog_cil_pcp *cilpcp; int cpu; int count = 0; @@ -171,13 +170,11 @@ xlog_cil_insert_pcp_aggregate( * structures that could have a nonzero space_used. */ for_each_cpu(cpu, &ctx->cil_pcpmask) { - int old, prev; + struct xlog_cil_pcp *cilpcp = per_cpu_ptr(cil->xc_pcp, cpu); + int old = READ_ONCE(cilpcp->space_used); - cilpcp = per_cpu_ptr(cil->xc_pcp, cpu); - do { - old = cilpcp->space_used; - prev = cmpxchg(&cilpcp->space_used, old, 0); - } while (old != prev); + while (!try_cmpxchg(&cilpcp->space_used, &old, 0)) + ; count += old; } atomic_add(count, &ctx->space_used); |