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From: "tj@kernel.org" <tj@kernel.org>
To: Bart Van Assche <Bart.VanAssche@wdc.com>
Cc: "mingo@kernel.org" <mingo@kernel.org>,
	"jthumshirn@suse.de" <jthumshirn@suse.de>,
	"oleg@redhat.com" <oleg@redhat.com>,
	"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	"ebiederm@xmission.com" <ebiederm@xmission.com>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"hare@suse.com" <hare@suse.com>,
	"jejb@linux.vnet.ibm.com" <jejb@linux.vnet.ibm.com>
Subject: Re: [PATCH, RESEND] Avoid that SCSI device removal through sysfs triggers a deadlock
Date: Mon, 30 Jul 2018 07:17:46 -0700	[thread overview]
Message-ID: <20180730141746.GD1206094@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <c313b5f09b6636fe71eb0a6c7390c3ef51869ae7.camel@wdc.com>

On Sun, Jul 29, 2018 at 04:03:41AM +0000, Bart Van Assche wrote:
> On Thu, 2018-07-26 at 06:35 -0700, Tejun Heo wrote:
> > Making removal asynchronous this way sometimes causes issues because
> > whether the user sees the device released or not is racy.
> 
> Hello Tejun,
> 
> How could this change cause any user-visible changes? My understanding is
> that any work queued with task_work_add() is executed before system call
> execution leaves kernel context and returns back to user space context.

Ah, you're right.  This isn't workqueue.  Hmm... yeah, needing to
allocate sth in removal path is a bit icky but, it should be okay I
guess.  I *think* the kernfs active break/unbreak is likely gonna be
cleaner tho.

Thanks.

-- 
tejun

      reply	other threads:[~2018-07-30 15:53 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-25 17:38 [PATCH, RESEND] Avoid that SCSI device removal through sysfs triggers a deadlock Bart Van Assche
2018-07-26  1:47 ` Martin K. Petersen
2018-07-26 11:46 ` Johannes Thumshirn
2018-07-26 11:46   ` Johannes Thumshirn
2018-07-26 12:50 ` Jack Wang
2018-07-26 13:35 ` Tejun Heo
2018-07-26 14:09   ` Bart Van Assche
2018-07-26 14:14     ` tj
2018-07-26 21:57       ` Bart Van Assche
2018-07-30 14:13         ` tj
2018-07-30 17:28           ` Bart Van Assche
2018-07-30 17:31             ` tj
2018-07-30 17:50               ` Bart Van Assche
2018-07-30 17:57                 ` tj
2018-07-29  4:03   ` Bart Van Assche
2018-07-30 14:17     ` tj [this message]

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