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| author | Uros Bizjak <ubizjak@gmail.com> | 2023-02-27 22:42:28 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-03-28 16:20:09 -0700 |
| commit | bdeb91881088810ab1d8ae620862c3b4d78f4041 (patch) | |
| tree | b5790da422d9eb9b58e4d08905ffb3ef84b60377 /mm/rmap.c | |
| parent | f2421a16f42a2f121c587c89b60cc8f3f2df36c2 (diff) | |
| download | lwn-bdeb91881088810ab1d8ae620862c3b4d78f4041.tar.gz lwn-bdeb91881088810ab1d8ae620862c3b4d78f4041.zip | |
mm/rmap: use atomic_try_cmpxchg in set_tlb_ubc_flush_pending
Use atomic_try_cmpxchg instead of atomic_cmpxchg (*ptr, old, new) == old
in set_tlb_ubc_flush_pending. 86 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.
No functional change intended.
Link: https://lkml.kernel.org/r/20230227214228.3533299-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 8632e02661ac..1ea2756b2797 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -644,7 +644,7 @@ void try_to_unmap_flush_dirty(void) static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) { struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; - int batch, nbatch; + int batch; arch_tlbbatch_add_mm(&tlb_ubc->arch, mm); tlb_ubc->flush_required = true; @@ -662,11 +662,8 @@ retry: * overflow. Reset `pending' and `flushed' to be 1 and 0 if * `pending' becomes large. */ - nbatch = atomic_cmpxchg(&mm->tlb_flush_batched, batch, 1); - if (nbatch != batch) { - batch = nbatch; + if (!atomic_try_cmpxchg(&mm->tlb_flush_batched, &batch, 1)) goto retry; - } } else { atomic_inc(&mm->tlb_flush_batched); } |