From: Christoph Hellwig <hch@infradead.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Christoph Hellwig <hch@infradead.org>,
"Martin K . Petersen" <martin.petersen@oracle.com>,
Jaegeuk Kim <jaegeuk@kernel.org>,
linux-scsi@vger.kernel.org,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
Can Guo <cang@codeaurora.org>, Bean Huo <beanhuo@micron.com>,
Stanley Chu <stanley.chu@mediatek.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Asutosh Das <asutoshd@codeaurora.org>,
Hannes Reinecke <hare@suse.com>,
John Garry <john.garry@huawei.com>
Subject: Re: [PATCH 2/2] scsi: ufs: Fix a deadlock in the error handler
Date: Wed, 3 Nov 2021 09:27:55 -0700 [thread overview]
Message-ID: <YYK4i6ak6Dqe1JeG@infradead.org> (raw)
In-Reply-To: <700f0463-23a9-8465-f712-1188cb884dea@acm.org>
On Wed, Nov 03, 2021 at 06:45:34AM -0700, Bart Van Assche wrote:
> > But more importantly: SCSI LLDDs have absolutel no business calling
> > blk_get_request or blk_mq_alloc_request directly, but as usual UFS is
> > completely fucked up here.
>
> As explained by Adrian, the UFS protocol uses a single tag space for SCSI
> commands and UFS device commands. blk_mq_alloc_request() is used in this
> context to allocate a tag only from the shared tag space only. I think using
> blk_mq_alloc_request() for that purpose is fine.
The problem is not the shared tag space, the problem is that it is
poking through layers. IFF we have good use cases for just allocating
a tag (and we don't want to reserve it, which does make sense for many
things like task management) we need a SCSI layer API that returns just
the tag (and preferably also poisons the request in some way).
next prev parent reply other threads:[~2021-11-03 16:28 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-03 0:05 [PATCH 0/2] Fix a deadlock in the UFS error handler Bart Van Assche
2021-11-03 0:05 ` [PATCH 1/2] scsi: core: Add support for reserved tags Bart Van Assche
2021-11-09 21:09 ` Bart Van Assche
2021-11-10 6:59 ` Hannes Reinecke
2021-11-10 19:19 ` Bart Van Assche
2021-11-11 6:54 ` Hannes Reinecke
2021-11-15 18:46 ` Bart Van Assche
2021-11-17 0:46 ` Bart Van Assche
2021-11-03 0:05 ` [PATCH 2/2] scsi: ufs: Fix a deadlock in the error handler Bart Van Assche
2021-11-03 6:56 ` Adrian Hunter
2021-11-03 13:40 ` Bart Van Assche
2021-11-03 14:03 ` Adrian Hunter
2021-11-07 11:07 ` Avri Altman
2021-11-08 18:26 ` Bart Van Assche
2021-11-03 7:40 ` Christoph Hellwig
2021-11-03 8:37 ` Adrian Hunter
2021-11-03 16:33 ` Christoph Hellwig
2021-11-03 16:48 ` Bart Van Assche
2021-11-03 13:45 ` Bart Van Assche
2021-11-03 16:27 ` Christoph Hellwig [this message]
2021-11-03 16:39 ` Bart Van Assche
2021-11-03 16:41 ` Christoph Hellwig
2022-02-18 18:04 [PATCH 0/2] Backport an UFS error handler fix to the 5.15 stable tree Bart Van Assche
2022-02-18 18:04 ` [PATCH 2/2] scsi: ufs: Fix a deadlock in the error handler Bart Van Assche
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