From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D665216CCFC; Fri, 29 Mar 2024 12:48:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711716526; cv=none; b=M6z8+LNVet3HZwX55v7RMILm0ZDp3/nKU71R55UL3COryT8Ixzw+yRuwTzRZwm9JSKj7XjGX3abPNmGUFaR+xMjo8P+5N9FXyxLAdObE86KAFO7W0UX4QEFNxezV9BCXqPs23pJfxNDqSLiYrfBxtfPL10D/uYK0bqeJWcfOERU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711716526; c=relaxed/simple; bh=tMQO/fg27rjZSTpk5zwZgWbnqjoNr/uW+lcI/B8sdCI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KS4v3LfynYMmAc1GC4HtsmeeSSJaF76O4nOkcSMpkzy/p6GDXixAC/NYcbQMR2LWbrvKsWKzCzkvzSyj1IwGVt0uSu9F8VXADm9i2No/KKyNIULhFgpGdHYkIcFeny0EEYxGugFHXpABSTcfcdoVeEmV1NAUTStHhQ3GNAnM6iw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cHzsGqs+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cHzsGqs+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D1E8FC433F1; Fri, 29 Mar 2024 12:48:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711716526; bh=tMQO/fg27rjZSTpk5zwZgWbnqjoNr/uW+lcI/B8sdCI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cHzsGqs+o2FvnJotNDeYEaxBktZhIzkA/YEyUVLGfkaCD94W648l9SF2cw5UPCYoO D5TacyY8lHiz8k1T/fXDixdPe3gCepQXxuDaI/hSIupdV6ffBIkWIbdw2+raXX9ziI yFKrUfh0ghuLy6IA3Pa0uul4+cJ48VcPyXmRpaGkWteiPAwvfqhNIe1LSRTzy5I7RL Z5qnUxAXwpWjSxQhCM1azcJBzJF+11eNMW+VHPeegiJ6vwqvKH4Wz9aiAoVKR9UFa6 uSKTPyzwLE+BRbUf99u3svL3BbS2JuTVkgpkcqejR/kaxNxdXkbS7WFt7aGi+VSMUq 0kkc03u48VbpQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: linke li , Masami Hiramatsu , Mathieu Desnoyers , Steven Rostedt , Sasha Levin , linux-trace-kernel@vger.kernel.org Subject: [PATCH AUTOSEL 5.15 34/34] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment Date: Fri, 29 Mar 2024 08:47:35 -0400 Message-ID: <20240329124750.3092394-34-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240329124750.3092394-1-sashal@kernel.org> References: <20240329124750.3092394-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.15.153 Content-Transfer-Encoding: 8bit From: linke li [ Upstream commit f1e30cb6369251c03f63c564006f96a54197dcc4 ] In function ring_buffer_iter_empty(), cpu_buffer->commit_page is read while other threads may change it. It may cause the time_stamp that read in the next line come from a different page. Use READ_ONCE() to avoid having to reason about compiler optimizations now and in future. Link: https://lore.kernel.org/linux-trace-kernel/tencent_DFF7D3561A0686B5E8FC079150A02505180A@qq.com Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Signed-off-by: linke li Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- kernel/trace/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index d9bed77f96c1f..2b46c66fb132d 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4343,7 +4343,7 @@ int ring_buffer_iter_empty(struct ring_buffer_iter *iter) cpu_buffer = iter->cpu_buffer; reader = cpu_buffer->reader_page; head_page = cpu_buffer->head_page; - commit_page = cpu_buffer->commit_page; + commit_page = READ_ONCE(cpu_buffer->commit_page); commit_ts = commit_page->page->time_stamp; /* -- 2.43.0