diff mbox series

[bpf-next,v3,1/7] mm/percpu.c: don't acquire pcpu_lock for pcpu_chunk_addr_search()

Message ID 20231020133202.4043247-2-houtao@huaweicloud.com (mailing list archive)
State Accepted
Commit 394e6869f0185e89cb815db29bf819474df858ae
Delegated to: BPF
Headers show
Series bpf: Fixes for per-cpu kptr | expand

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bpf/vmtest-bpf-next-PR fail merge-conflict
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1363 this patch: 1363
netdev/cc_maintainers success CCed 6 of 6 maintainers
netdev/build_clang success Errors and warnings before: 1386 this patch: 1386
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netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
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netdev/source_inline success Was 0 now: 0

Commit Message

Hou Tao Oct. 20, 2023, 1:31 p.m. UTC 
From: Hou Tao <houtao1@huawei.com>

There is no need to acquire pcpu_lock for pcpu_chunk_addr_search():
1) both pcpu_first_chunk & pcpu_reserved_chunk must have been
   initialized before the invocation of free_percpu().
2) The dynamically-created chunk must be valid before the per-cpu
   pointers allocated from it are freed.

So acquire pcpu_lock() after the invocation of pcpu_chunk_addr_search().

Acked-by: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 mm/percpu.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/mm/percpu.c b/mm/percpu.c
index 7b40b3963f106..76b9c5e63c562 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -2267,12 +2267,10 @@  void free_percpu(void __percpu *ptr)
 	kmemleak_free_percpu(ptr);
 
 	addr = __pcpu_ptr_to_addr(ptr);
-
-	spin_lock_irqsave(&pcpu_lock, flags);
-
 	chunk = pcpu_chunk_addr_search(addr);
 	off = addr - chunk->base_addr;
 
+	spin_lock_irqsave(&pcpu_lock, flags);
 	size = pcpu_free_area(chunk, off);
 
 	pcpu_memcg_free_hook(chunk, off, size);