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From: Yonghong Song <yonghong.song@linux.dev>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	kernel-team@fb.com, Martin KaFai Lau <martin.lau@kernel.org>
Subject: [PATCH bpf-next] bpf: Remove unnecessary cpu == 0 check in memalloc
Date: Thu,  4 Jan 2024 08:57:44 -0800	[thread overview]
Message-ID: <20240104165744.702239-1-yonghong.song@linux.dev> (raw)

After merging the patch set [1] to reduce memory usage
for bpf_global_percpu_ma, Alexei found a redundant check (cpu == 0)
in function bpf_mem_alloc_percpu_unit_init() ([2]).
Indeed, the check is unnecessary since c->unit_size will
be all NULL or all non-NULL for all cpus before
for_each_possible_cpu() loop.
Removing the check makes code less confusing.

  [1] https://lore.kernel.org/all/20231222031729.1287957-1-yonghong.song@linux.dev/
  [2] https://lore.kernel.org/all/20231222031745.1289082-1-yonghong.song@linux.dev/

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
 kernel/bpf/memalloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c
index 460c8f38fed6..550f02e2cb13 100644
--- a/kernel/bpf/memalloc.c
+++ b/kernel/bpf/memalloc.c
@@ -613,7 +613,7 @@ int bpf_mem_alloc_percpu_unit_init(struct bpf_mem_alloc *ma, int size)
 	for_each_possible_cpu(cpu) {
 		cc = per_cpu_ptr(pcc, cpu);
 		c = &cc->cache[i];
-		if (cpu == 0 && c->unit_size)
+		if (c->unit_size)
 			break;
 
 		c->unit_size = unit_size;
-- 
2.34.1


             reply	other threads:[~2024-01-04 16:57 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-04 16:57 Yonghong Song [this message]
2024-01-04 18:20 ` [PATCH bpf-next] bpf: Remove unnecessary cpu == 0 check in memalloc patchwork-bot+netdevbpf

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