linux-kernel - Re: [PATCH] blkmq: Fix NULL pointer deref when all reserved tags in use

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Message-ID: <5509E8CB.8020404@micron.com>
Date:	Wed, 18 Mar 2015 14:06:19 -0700
From:	Sam Bradshaw <sbradshaw@...ron.com>
To:	Jens Axboe <axboe@...nel.dk>
CC:	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] blkmq: Fix NULL pointer deref when all reserved tags
 in use


> Good catch! But why not put the hctx == NULL check in as a conditional
> in bt_get() before running the queue? I can't imagine other cases where
> calling blk_mq_run_hw_queue() with hctx == NULL would be a valid scenario.

The change was meant to be broad in scope.  A runtime NULL deref is a 
rather unfortunate way to determine that there are other invalid scenarios.

But given that both approaches fix the immediate problem, I'd be happy 
to change the patch as you suggest.



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