From: Bart Van Assche <Bart.VanAssche@sandisk.com>
To: "osandov@osandov.com" <osandov@osandov.com>
Cc: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"James.Bottomley@HansenPartnership.com"
<James.Bottomley@HansenPartnership.com>,
"hare@suse.com" <hare@suse.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"osandov@fb.com" <osandov@fb.com>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"axboe@kernel.dk" <axboe@kernel.dk>
Subject: Re: [PATCH v5 10/10] scsi: Implement blk_mq_ops.show_rq()
Date: Tue, 25 Apr 2017 22:06:24 +0000 [thread overview]
Message-ID: <1493157983.2628.24.camel@sandisk.com> (raw)
In-Reply-To: <20170425213956.GD6361@vader>
On Tue, 2017-04-25 at 14:39 -0700, Omar Sandoval wrote:
> On Tue, Apr 25, 2017 at 01:37:45PM -0700, Bart Van Assche wrote:
> > Show the SCSI CDB, .eh_eflags and .result for pending SCSI commands
> > in /sys/kernel/debug/block/*/mq/*/dispatch and */rq_list.
>=20
> Only thing I noticed was that the only other caller I see has buf[70].
> No idea if that's a meaningful number. For the sake of this not getting
> bike-shedded to death,
Neither length is sufficient to avoid truncation of e.g. ATA pass-through
commands or commands with variable length CDBs. However, from the point of
view of debugging queue lockups the most useful information in a SCSI
command are the first two bytes of the CDB. The chosen buffer length is
definitely enough to make sure that these two bytes will be reported.
Bart.=
WARNING: multiple messages have this Message-ID (diff)
From: Bart Van Assche <Bart.VanAssche@sandisk.com>
To: "osandov@osandov.com" <osandov@osandov.com>
Cc: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"James.Bottomley@HansenPartnership.com"
<James.Bottomley@HansenPartnership.com>,
"hare@suse.com" <hare@suse.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"osandov@fb.com" <osandov@fb.com>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"axboe@kernel.dk" <axboe@kernel.dk>
Subject: Re: [PATCH v5 10/10] scsi: Implement blk_mq_ops.show_rq()
Date: Tue, 25 Apr 2017 22:06:24 +0000 [thread overview]
Message-ID: <1493157983.2628.24.camel@sandisk.com> (raw)
In-Reply-To: <20170425213956.GD6361@vader>
On Tue, 2017-04-25 at 14:39 -0700, Omar Sandoval wrote:
> On Tue, Apr 25, 2017 at 01:37:45PM -0700, Bart Van Assche wrote:
> > Show the SCSI CDB, .eh_eflags and .result for pending SCSI commands
> > in /sys/kernel/debug/block/*/mq/*/dispatch and */rq_list.
>
> Only thing I noticed was that the only other caller I see has buf[70].
> No idea if that's a meaningful number. For the sake of this not getting
> bike-shedded to death,
Neither length is sufficient to avoid truncation of e.g. ATA pass-through
commands or commands with variable length CDBs. However, from the point of
view of debugging queue lockups the most useful information in a SCSI
command are the first two bytes of the CDB. The chosen buffer length is
definitely enough to make sure that these two bytes will be reported.
Bart.
next prev parent reply other threads:[~2017-04-25 22:06 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-25 20:37 [PATCH v5 00/10] blk-mq debugfs patches for kernel v4.12 Bart Van Assche
2017-04-25 20:37 ` [PATCH v5 01/10] blk-mq: Register <dev>/queue/mq after having registered <dev>/queue Bart Van Assche
2017-04-25 20:37 ` [PATCH v5 02/10] blk-mq: Let blk_mq_debugfs_register() look up the queue name Bart Van Assche
2017-04-25 20:37 ` [PATCH v5 03/10] blk-mq-debugfs: Rename functions for registering and unregistering the mq directory Bart Van Assche
2017-04-25 20:37 ` [PATCH v5 04/10] blk-mq: Only unregister hctxs for which registration succeeded Bart Van Assche
2017-04-25 21:18 ` Omar Sandoval
2017-04-25 20:37 ` [PATCH v5 05/10] blk-mq: Unregister debugfs attributes earlier Bart Van Assche
2017-04-25 21:30 ` Omar Sandoval
2017-04-25 21:41 ` Jens Axboe
2017-04-26 20:38 ` Bart Van Assche
2017-04-25 22:24 ` Bart Van Assche
2017-04-25 22:29 ` Jens Axboe
2017-04-25 22:30 ` Omar Sandoval
2017-04-26 20:32 ` Bart Van Assche
2017-04-26 20:37 ` Jens Axboe
2017-04-26 20:37 ` Omar Sandoval
2017-04-25 20:37 ` [PATCH v5 06/10] blk-mq: Move the "state" debugfs attribute one level down Bart Van Assche
2017-04-25 20:37 ` [PATCH v5 07/10] blk-mq: Make blk_flags_show() callers append a newline character Bart Van Assche
2017-04-25 20:37 ` [PATCH v5 08/10] blk-mq: Show operation, cmd_flags and rq_flags names Bart Van Assche
2017-04-25 20:37 ` [PATCH v5 09/10] blk-mq: Add blk_mq_ops.show_rq() Bart Van Assche
2017-04-25 21:35 ` Omar Sandoval
2017-04-25 20:37 ` [PATCH v5 10/10] scsi: Implement blk_mq_ops.show_rq() Bart Van Assche
2017-04-25 20:37 ` Bart Van Assche
2017-04-25 21:39 ` Omar Sandoval
2017-04-25 22:06 ` Bart Van Assche [this message]
2017-04-25 22:06 ` Bart Van Assche
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