From: Christoph Hellwig <hch@infradead.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-scsi@vger.kernel.org,
"James E.J. Bottomley" <JBottomley@odin.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
rt@linutronix.de, Vasu Dev <vasu.dev@intel.com>,
Christoph Hellwig <hch@lst.de>,
fcoe-devel@open-fcoe.org
Subject: Re: [PATCH 01/11] scsi/fcoe: lock online CPUs in fcoe_percpu_clean()
Date: Fri, 11 Mar 2016 08:17:04 -0800 [thread overview]
Message-ID: <20160311161704.GA5083@infradead.org> (raw)
In-Reply-To: <1457710143-29182-2-git-send-email-bigeasy@linutronix.de>
On Fri, Mar 11, 2016 at 04:28:53PM +0100, Sebastian Andrzej Siewior wrote:
> for_each_possible_cpu() with a cpu_online() + `thread' check possibly does
> the job. But there is a tiny race: Say CPU5 is reported online but is
> going down. And after fcoe_percpu_clean() saw that CPU5 is online it
> decided to enqueue a packet. After dev_alloc_skb() returned a skb
> that CPU is offline (or say the notifier destroyed the kthread). So we
> would OOps because `thread' is NULL.
> An alternative would be to lock the CPUs during our loop (so no CPU is
> going away) and then we iterate over the online mask.
I've looked over this and the following patches, and I suspect
the right thing to do for fcoe and bnx2 is to convert them to use the
generic workqueue code instead of reinventing it poorly.
next prev parent reply other threads:[~2016-03-11 16:17 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-11 15:28 [PATCH 00/11] SCSI smpboot thread conversion Sebastian Andrzej Siewior
2016-03-11 15:28 ` [PATCH 01/11] scsi/fcoe: lock online CPUs in fcoe_percpu_clean() Sebastian Andrzej Siewior
2016-03-11 16:17 ` Christoph Hellwig [this message]
2016-03-11 16:32 ` Sebastian Andrzej Siewior
2016-03-15 8:19 ` Christoph Hellwig
2016-04-08 13:30 ` Sebastian Andrzej Siewior
2016-04-08 18:14 ` Sebastian Andrzej Siewior
2016-04-12 15:16 ` [PATCH v2] scsi/fcoe: convert to kworker Sebastian Andrzej Siewior
2016-04-22 15:27 ` [PREEMPT-RT] " Sebastian Andrzej Siewior
2016-04-22 15:49 ` James Bottomley
2016-04-22 16:39 ` Laurence Oberman
[not found] ` <186981952.31194082.1461343179889.JavaMail.zimbra-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-06-09 13:09 ` Sebastian Andrzej Siewior
2016-06-09 13:15 ` Laurence Oberman
2016-06-09 13:22 ` Sebastian Andrzej Siewior
2016-06-10 10:38 ` Johannes Thumshirn
[not found] ` <20160610103812.ojgzop6qdv3mos5d-3LAbnSA0sDC4fIQPS+WK3rNAH6kLmebB@public.gmane.org>
2016-07-01 19:09 ` Bynoe, Ronald J
2016-07-04 8:23 ` Sebastian Andrzej Siewior
2016-03-11 15:28 ` [PATCH 02/11] scsi/fcoe: remove CONFIG_SMP in fcoe_percpu_thread_destroy() Sebastian Andrzej Siewior
2016-03-11 15:28 ` [PATCH 03/11] scsi/fcoe: drop locking in fcoe_percpu_thread_destroy() if cpu == targ_cpu Sebastian Andrzej Siewior
2016-03-11 15:28 ` [PATCH 04/11] scsi/fcoe: rename p0 to p_target in fcoe_percpu_thread_destroy() Sebastian Andrzej Siewior
2016-03-11 15:28 ` [PATCH 05/11] scsi/fcoe: drop the p_target lock earlier if there is no thread online Sebastian Andrzej Siewior
2016-03-11 15:28 ` [PATCH 06/11] scsi/fcoe: use skb_queue_splice_tail() intead of manual job Sebastian Andrzej Siewior
2016-03-11 15:28 ` [PATCH 07/11] scsi/fcoe: drop the crc_eof page early Sebastian Andrzej Siewior
2016-03-11 15:29 ` [PATCH 08/11] scsi/fcoe: convert to smpboot thread Sebastian Andrzej Siewior
2016-03-11 15:29 ` [PATCH 09/11] scsi: bnx2i: " Sebastian Andrzej Siewior
2016-03-11 15:29 ` [PATCH 10/11] scsi: bnx2fc: fix hotplug race in bnx2fc_process_new_cqes() Sebastian Andrzej Siewior
2016-03-11 15:29 ` [PATCH 11/11] scsi: bnx2fc: convert to smpboot thread Sebastian Andrzej Siewior
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