From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=216.40.44.16 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794480375; b=vLLCAhSo0WBBoQYS119rqklThdcsDJnS0L6GOPWUsxlXinicfBX/drCfmWSLhhQZjQ0I jx6H53vz2pnCsg0Uzk8apgQxEiUs2/HLX+Ri3OoWB+QM49XzjyauzdvcdHL8QxheITfri Q4zLE9633TJsu45fPJBpBtfzZEVPXh0CEZLqfR+hb1X4NkcnJe0CrtA9wTQPm0pZ5Ut8d 6YZcxEgbwXw+eVgFuE6S04CWHH/g9VA3gdq+jjd6SEoSec09SwfFwmVf5o+81stN4L4Xs uyoct5nk09FtnGieHCk9SdhVolRDgesrmYzzsnRM7R+MkMltf9sULxldGWAHwziF3bg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794480375; h=DMARC-Filter:Received:Received:Date:From:To:Cc:Subject:Message-ID: In-Reply-To:References:X-Mailer:MIME-Version:Content-Type: Content-Transfer-Encoding:X-Rspamd-Server:X-Rspamd-Queue-Id: X-Stat-Signature:X-Spam-Status:X-Session-Marker:X-Session-ID: DKIM-Signature:X-HE-Tag:X-HE-Meta; bh=4jX3n0IQNsJJSebGl5jsOUkEUs41MB88RY8wsSX2rZ8=; b=t1kYpbC4dee/ZBkwHtSDsX3ipl1rtvUvH6Mm0waVpa7lhJAF7kUsBzj+dGEsQBhrpJEM kuZV52qEFkxHd27VoSpMp/nEUPS/tZfG73Q3Bylwz5XS5aoyTxi8u8xv+L3MSbgolksDN 2xXTjm91b2tkDqVcnibROEym0giIp4mvX28uiA/xglQFsPW3LFXLPeuaNvU/GPT5V7hDW 6VOnZhZFudU08UVyyp5eFMHvAmEXpNBNRmXodC0ksc/S8jLraTlBVp3yj+Y4mocFKx6A6 38S/FNk6ZTBz81oB6myuRGsjqmpcLkR+Z3O4FRdX6Ahl12dRi3qeDzUapj3IVN8rLqA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; dkim=pass header.d=goodmis.org header.i=@goodmis.org header.a=rsa-sha256 header.s=dkim1 header.b=Lt57riGj; arc=none smtp.remote-ip=216.40.44.16 Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A9311606A32A; Thu, 12 Nov 2026 10:46:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org A9311606A32A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=goodmis.org header.i=@goodmis.org header.a=rsa-sha256 header.s=dkim1 header.b=Lt57riGj Received: from omf17.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 1D54BC052E; Thu, 12 Nov 2026 10:46:07 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf17.hostedemail.com (Postfix) with ESMTPA id 6234F18; Thu, 12 Nov 2026 10:45:57 +0000 (UTC) Date: Thu, 12 Nov 2026 05:45:42 -0500 From: Steven Rostedt To: Zhu Jun Cc: vdonnefort@google.com, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+53ab168fdda7fba508ba@syzkaller.appspotmail.com Subject: Re: [PATCH] ring-buffer: Mark concurrent accesses to waiter flags Message-ID: <20261112054542.63b29e3d@fedora> In-Reply-To: <20261111084137.80941-1-zhujun2@cmss.chinamobile.com> References: <20261111084137.80941-1-zhujun2@cmss.chinamobile.com> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspamout05 X-Rspamd-Queue-Id: 6234F18 X-Stat-Signature: hk6uimtb77artkm8irgdw7r6jydi5o5d X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX18/nl8pFVqTmrcJK8eLcjmxGhEeLuHz1Wg= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=goodmis.org; h=date:from:to:cc:subject:message-id:in-reply-to:references:mime-version:content-type:content-transfer-encoding; s=dkim1; bh=4jX3n0IQNsJJSebGl5jsOUkEUs41MB88RY8wsSX2rZ8=; b=Lt57riGjbO+Psp+UTt4upS26k3EFr3HFO1wdYtg4nHDOgK3ES+fYITRLYfSOJovRIFfbrb1sGSA9ATjQzE+XXonEXZtka90YsmuTNJpHkRgd4obu0diFAzAw/ZAO0Fa8oApLUa88bcx+jgHy4u8ykS5Ahe9dWXJx1usnV9L9zHw= X-HE-Tag: 1794480357-426971 X-HE-Meta: U2FsdGVkX1+eIOTWXKADAjXWWOcoYfYM3njnhOsbJZUsJ3xR/8aWoUxt7uEND4yfBzmDOVtqm0imddAE8bvm1jgaFyZwm51rXSFRmihr5EIxRcJqXfG0hmqd3pvMGDiFwnFD/bQ8si/lyMxS3Nce94NVPicv13EqG92HuV6xtaFXGykjfNgOua0jppwycSPp+rUDg1Dm8KKooLacNJD3TaZIjgP8cOa1qV4dzrhW56Uk21KVygVGmuf3LS1yULruMAXtYJGLh6yt6YNh6fzcjGb0uSRpvpnDYEAoMPIzn9zCmL1no0yIrkYAC27jsH3vtXa/n7qV/1LYQ1FlDqrqzaO0n6gizP/q On Wed, 11 Nov 2026 16:41:37 +0800 Zhu Jun wrote: > Poll and wait paths set the pending waiter flags while ring buffer > writers test and clear them without a common lock. The irq_work callback > also accesses the full-buffer wakeup flags concurrently. These plain > accesses cause KCSAN reports. > > Use READ_ONCE() and WRITE_ONCE() for the shared waiter and wakeup flags. > Keep the existing barriers and irq_work wakeup protocol unchanged. > > Fixes: 15693458c4bc ("tracing/ring-buffer: Move poll wake ups into ring buffer code") > Fixes: 1e0d6714aceb ("ring-buffer: Do not wake up a splice waiter when page is not full") > Signed-off-by: Zhu Jun Is this simply to prevent read/write tearing? -- Steve