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Sat, 27 Jan 2024 20:19:42 -0800 (PST) Received: from ubuntu.localdomain ([219.143.159.9]) by smtp.gmail.com with ESMTPSA id x15-20020a17090a164f00b00295210e5a9asm2442047pje.48.2024.01.27.20.19.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 27 Jan 2024 20:19:41 -0800 (PST) From: Donglin Peng To: peterz@infradead.org Cc: jolsa@kernel.org, wangnan0@huawei.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, Donglin Peng Subject: [PATCH] perf/ring-buffer: refactor code of reading the value of data_tail Date: Sat, 27 Jan 2024 20:19:35 -0800 Message-Id: <20240128041935.513800-1-dolinux.peng@gmail.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1789306443989292573 X-GMAIL-MSGID: 1789306443989292573 The tail variable will only be accessed when overwrite is 0, so we can put the assignment statement in the if branch. Fixes: d1b26c70246b ("perf/ring_buffer: Prepare writing into the ring-buffer from the end") Signed-off-by: Donglin Peng --- kernel/events/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 60ed43d1c29e..86b150a822b7 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -194,8 +194,8 @@ __perf_output_begin(struct perf_output_handle *handle, offset = local_read(&rb->head); do { head = offset; - tail = READ_ONCE(rb->user_page->data_tail); if (!rb->overwrite) { + tail = READ_ONCE(rb->user_page->data_tail); if (unlikely(!ring_buffer_has_space(head, tail, perf_data_size(rb), size, backward)))