From: James Bottomley <James.Bottomley@steeleye.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Mike Christie <mikenc@us.ibm.com>,
SCSI Mailing List <linux-scsi@vger.kernel.org>
Subject: Re: [PATCH] fixes compile errors in cpqfcTS driver
Date: 22 Apr 2003 08:54:50 -0500 [thread overview]
Message-ID: <1051019692.1768.7.camel@mulgrave> (raw)
In-Reply-To: <20030422074414.A26090@infradead.org>
On Tue, 2003-04-22 at 01:44, Christoph Hellwig wrote:
> I don't think the onstack command/device will work anymore.
> You'll have to use scsi_get_command/scsi_put_command I guess
Actually on stack command allocation never was legal, although we seem
to have quite a few drivers that do it. The reason (aside from the fact
that the stack is a precious resource in the kernel) is that struct
scsi_cmnds can be used by the driver to DMA to the device and DMAable
memory should never be allocated on the stack (mainly because of
alignment and flushing issues that can cause memory corruption).
Unfortunately, the bugs stack allocation causes don't show up on the x86
architecture giving a driver that seems to work for the majority of
users but which can cause weird hangs and crashes on non-x86 platforms.
James
prev parent reply other threads:[~2003-04-22 13:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-21 23:57 [PATCH] fixes compile errors in cpqfcTS driver Mike Christie
2003-04-22 6:44 ` Christoph Hellwig
2003-04-22 13:54 ` James Bottomley [this message]
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