From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 013.lax.mailroute.net (013.lax.mailroute.net [199.89.1.16]) (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 10F2421CC5A; Thu, 15 Jan 2026 17:24:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.1.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768497881; cv=none; b=K+MaueoJSWVbLp5lRATrLto/6KJMQuAYsvqva8/85CaXrpO9W1P14Qs0aqGGd+RUIjsH1tELbSei6g/v3ulldPXxIxE+ywx7Lqgybqo63GxQt/eVz6djpYySwyHwjtc6rG5PjgjLxLo3wUdI+lotD5iIyTm1RAQUcdYYQgggpKc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768497881; c=relaxed/simple; bh=kA8TtiYYt8fK0wKpjyawQNU2b8oLDjq6/qKRYGeh5uk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RgwXETF1ftZyrGdLMhASK674qPhhY1QVrX/K7CFximJZPOQJHVXLvRRLqMoCKMJwtef0LB8/bRsh7fMlS49h46UY7lXAZPiy4s8nayLIJySXyHfgZGji0NfYG71Z1L0LYbCFVhgFgJaVPwurbGi0mmfOrqYIyrwMzDGR1Axgu/g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org; spf=pass smtp.mailfrom=acm.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b=gK8JoBX+; arc=none smtp.client-ip=199.89.1.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=acm.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b="gK8JoBX+" Received: from localhost (localhost [127.0.0.1]) by 013.lax.mailroute.net (Postfix) with ESMTP id 4dsVGb2qFJzlgqwC; Thu, 15 Jan 2026 17:24:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=acm.org; h= content-transfer-encoding:content-type:content-type:in-reply-to :from:from:content-language:references:subject:subject :user-agent:mime-version:date:date:message-id:received:received; s=mr01; t=1768497877; x=1771089878; bh=jDnusECdqKbA9rbaoSbkLQ7Y gd9BkGFdKUj9YuPUREo=; b=gK8JoBX+scOsbxpU6H8KopsdsjnJ4c3rogB7geh1 Y71kLj5ZVbGYVOUsl+25oSNqz/hEt5p9/sHXsClKI518LclqkAr3m2xinXVY1fsk 4pA3S3WIPbk7E5r6cZXnvFHVWfHwKKZcNoBT3eXIbh0yItyhk/8CEWaHrsWxpfK6 qRGgJ/Y4FCs8CXjVHfGUIvSr1HBhlCCYNt2mhDHOjT2xjsSO3r+L6Ox0tRo5cZ+N aXjI/Om5n+c8dAGEcEpMHUL0EmNchI5BUOHVqEbd+ac43kUix7jcb7DcLNoupbTn Vlex6zo62MyYcYZ1zblo5bIvFv3I4ISZ7UEokLrWLkd9Tw== X-Virus-Scanned: by MailRoute Received: from 013.lax.mailroute.net ([127.0.0.1]) by localhost (013.lax [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id 1WdAK39IiQ5V; Thu, 15 Jan 2026 17:24:37 +0000 (UTC) Received: from [IPV6:2a00:79e0:2e7c:9:1de3:5bc8:3be1:d169] (unknown [104.135.180.217]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) (Authenticated sender: bvanassche@acm.org) by 013.lax.mailroute.net (Postfix) with ESMTPSA id 4dsVGX4fcTzlgqsP; Thu, 15 Jan 2026 17:24:36 +0000 (UTC) Message-ID: <2c210e30-e7bd-4b70-ad4e-cc7a1bbb5309@acm.org> Date: Thu, 15 Jan 2026 09:24:34 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] scsi: pm8001: Fix data race in sysfs SAS address read To: Chengfeng Ye , "James E . J . Bottomley" , "Martin K . Petersen" Cc: Jack Wang , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260115171140.281969-1-cyeaa@connect.ust.hk> Content-Language: en-US From: Bart Van Assche In-Reply-To: <20260115171140.281969-1-cyeaa@connect.ust.hk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/15/26 9:11 AM, Chengfeng Ye wrote: > diff --git a/drivers/scsi/pm8001/pm8001_ctl.c b/drivers/scsi/pm8001/pm8001_ctl.c > index cbfda8c04e95..e49f11969b3b 100644 > --- a/drivers/scsi/pm8001/pm8001_ctl.c > +++ b/drivers/scsi/pm8001/pm8001_ctl.c > @@ -311,8 +311,15 @@ static ssize_t pm8001_ctl_host_sas_address_show(struct device *cdev, > struct Scsi_Host *shost = class_to_shost(cdev); > struct sas_ha_struct *sha = SHOST_TO_SAS_HA(shost); > struct pm8001_hba_info *pm8001_ha = sha->lldd_ha; > - return sysfs_emit(buf, "0x%016llx\n", > - be64_to_cpu(*(__be64 *)pm8001_ha->sas_addr)); > + unsigned long flags; > + ssize_t ret; > + > + spin_lock_irqsave(&pm8001_ha->lock, flags); > + ret = sysfs_emit(buf, "0x%016llx\n", > + be64_to_cpu(*(__be64 *)pm8001_ha->sas_addr)); > + spin_unlock_irqrestore(&pm8001_ha->lock, flags); > + > + return ret; > } > static DEVICE_ATTR(host_sas_address, S_IRUGO, > pm8001_ctl_host_sas_address_show, NULL); Why isn't READ_ONCE() sufficient? And why explicit spin_lock_irqsave() and spin_unlock_irqrestore() calls instead of using scoped_guard()? Bart.