From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Christoph Hellwig <hch@infradead.org>
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 17:32:15 +0100 [thread overview]
Message-ID: <56E2F30F.5030108@linutronix.de> (raw)
In-Reply-To: <20160311161704.GA5083@infradead.org>
On 03/11/2016 05:17 PM, Christoph Hellwig wrote:
> 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.
alloc_workqueue() in setup and then queue_work_on(cpu, , item)? item
should be struct work_struct but all I have is a skb. Is there an easy
way to get this attached?
Sebastian
next prev parent reply other threads:[~2016-03-11 16:32 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
2016-03-11 16:32 ` Sebastian Andrzej Siewior [this message]
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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