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 AD75816DEAB; Fri, 29 Mar 2024 12:49:54 +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=1711716594; cv=none; b=lp1zsfih4qEJqmksjDkNgVhnTMRNaoueph+bBfJGkOcWb2lUmac/5RizTWiYCiEk54IC4GyI1lvMF2J98MdV+ZlXh73mL8cNS6RNQTz30RAxSzYzd+UOzSexXefUL5s4S9KEyygwl0puLxdDEXq7CuzTp6Yy+5FtfXbYkMt6Tio= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711716594; c=relaxed/simple; bh=Fi6yVVB6Z/n/Z3zZqPWLKyoNA00zs1e+JgIjJZ+Pwk4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sL8epQr/h9jIg/IgXe7a/IMroG73i0My72cw/FJkZN7BQLqAO7Xm3tXnkZAirSWkKCBuOwvlX/KloxxQtMwZPFh+1Xw4wwRA/7vAhsBAuWAp/etXcuOOdHGupfS4GvUCZRIdYXN62DaZCW8L9BU5yukjGKg5iTO1pvlh56BgDZg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FV6ovQk3; 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="FV6ovQk3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ABB02C433F1; Fri, 29 Mar 2024 12:49:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711716594; bh=Fi6yVVB6Z/n/Z3zZqPWLKyoNA00zs1e+JgIjJZ+Pwk4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FV6ovQk3VvmF287IgU7LtnrqIHiAptc2cZCzJZLl1vV22ULsMuuMQ1uJRFu96Wr/0 EteM5Ja1byoA1H5RI4ctd1LiI32K8laU+wLokF8DgOt6nOQE7g3Da4lbuAvXqdxICv LuCRRhrgBf05D/fvzKAlaLvI9Wr7HArL6lgIyk0t+ls4Vzvj3NfYw74rp+3ldjsp1Q VlhZwHYhzmf99cWlmBDM9rZqmkqTaL70pUFhpFC0n3IypnN2XwRZuyNLmUN/YVK7al KZfYPDDlo1SLAZ4FVNzyfQojPedwdcKyCcJfjRUOUgdQzu7PRbilEl3GGKSSOMOFkL va4rmtA/fHpTA== 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 5.10 31/31] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment Date: Fri, 29 Mar 2024 08:48:48 -0400 Message-ID: <20240329124903.3093161-31-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240329124903.3093161-1-sashal@kernel.org> References: <20240329124903.3093161-1-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 5.10.214 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 4a43b8846b49f..70b6cb6bfb56e 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4184,7 +4184,7 @@ 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