From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-scsi@vger.kernel.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH scsi] Add NULL checking of return value from scsi_cmd_to_driver()
Date: Mon, 24 Sep 2012 09:44:53 +0400 [thread overview]
Message-ID: <1348465493.2467.3.camel@dabdike> (raw)
In-Reply-To: <1348464626.2475.13.camel@ThinkPad-T420>
On Mon, 2012-09-24 at 13:30 +0800, Li Zhong wrote:
> Just noticed that after commit 919f797, it is possible that
> scsi_cmd_to_driver() returns NULL. This patch adds the NULL checking for drv
> returned from the above function.
>
> Maybe it is not possible at run time, but from the code itself, we'd better
> have this check?
There's not much point having a check that never trips, unless it's an
assert, in which case a NULL deref does that. All it does is add
pointless instructions to the critical path. only REQ_TYPE_BLOCK_PC
commands can be submitted without a driver, so the check above would
seem to preclude that.
James
next prev parent reply other threads:[~2012-09-24 5:44 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-24 5:30 [PATCH scsi] Add NULL checking of return value from scsi_cmd_to_driver() Li Zhong
2012-09-24 5:44 ` James Bottomley [this message]
2012-09-24 7:03 ` Li Zhong
2012-09-24 7:35 ` James Bottomley
2012-09-24 9:25 ` Li Zhong
2012-09-24 9:33 ` James Bottomley
2012-09-27 2:02 ` Martin K. Petersen
2012-09-27 4:44 ` James Bottomley
2012-09-27 9:51 ` [PATCH scsi] Short the path length of scsi_cmd_to_driver() Li Zhong
2012-09-27 17:43 ` Martin K. Petersen
2012-09-28 7:13 ` Li Zhong
2012-09-28 7:45 ` James Bottomley
2012-09-27 17:41 ` [PATCH scsi] Add NULL checking of return value from scsi_cmd_to_driver() Martin K. Petersen
2012-09-28 7:48 ` James Bottomley
2012-09-29 4:23 ` [PATCH v2 scsi] Short the path length of scsi_cmd_to_driver() Li Zhong
2012-10-02 22:22 ` Martin K. Petersen
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