From: Bart Van Assche <bvanassche@acm.org>
To: James Hogan <james.hogan@imgtec.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>,
linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH] scsi: make struct scsi_varlen_cdb_hdr packed
Date: Thu, 11 Oct 2012 12:01:48 +0200 [thread overview]
Message-ID: <5076990C.4080406@acm.org> (raw)
In-Reply-To: <1349946933-30314-1-git-send-email-james.hogan@imgtec.com>
On 10/11/12 11:15, James Hogan wrote:
> The struct scsi_varlen_cdb_hdr is expected to be exactly 10 bytes when
> used in struct osd_cdb_head, but it isn't marked as packed. Some
> architectures will round the struct size up which triggers BUILD_BUG_ON
> compile errors in osd_initiator.c when the outer structs are unexpected
> sizes. This is fixed by marking struct scsi_varlen_cdb_hdr as __packed.
>
> Signed-off-by: James Hogan <james.hogan@imgtec.com>
> ---
> include/scsi/scsi.h | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
> index 66216c1..3beaef3 100644
> --- a/include/scsi/scsi.h
> +++ b/include/scsi/scsi.h
> @@ -198,7 +198,7 @@ struct scsi_varlen_cdb_hdr {
> __u8 additional_cdb_length; /* total cdb length - 8 */
> __be16 service_action;
> /* service specific data follows */
> -};
> +} __packed;
>
> static inline unsigned
> scsi_varlen_cdb_length(const void *hdr)
Hello James,
Are you aware that __packed can also be used on individual struct
members and that doing so has a lower performance penalty than using the
__packed attribute on an entire struct ? See e.g. <linux/sysv_fs.h> for
an example.
Bart.
next prev parent reply other threads:[~2012-10-11 10:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-11 9:15 [RESEND PATCH] scsi: make struct scsi_varlen_cdb_hdr packed James Hogan
2012-10-11 10:01 ` Bart Van Assche [this message]
2012-10-11 11:13 ` James Hogan
2012-10-11 10:24 ` James Bottomley
2012-10-11 11:32 ` James Hogan
2012-10-11 12:58 ` James Bottomley
2012-10-11 13:34 ` Alan Cox
2012-10-11 14:10 ` James Hogan
2013-02-11 12:55 ` James Hogan
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