[SCSI] use dynamically allocated sense buffer

This removes static array sense_buffer in scsi_cmnd and uses
dynamically allocated sense_buffer (with GFP_DMA).

The reason for doing this is that some architectures need cacheline
aligned buffer for DMA:

http://lkml.org/lkml/2007/11/19/2

The problems are that scsi_eh_prep_cmnd puts scsi_cmnd::sense_buffer
to sglist and some LLDs directly DMA to scsi_cmnd::sense_buffer. It's
necessary to DMA to scsi_cmnd::sense_buffer safely. This patch solves
these issues.

__scsi_get_command allocates sense_buffer via kmem_cache_alloc and
attaches it to a scsi_cmnd so everything just work as before.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 3f47e522a1ec..abd7479ff452 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -88,7 +88,7 @@ struct scsi_cmnd {
                                            working on */
 
 #define SCSI_SENSE_BUFFERSIZE   96
-        unsigned char sense_buffer[SCSI_SENSE_BUFFERSIZE];
+        unsigned char *sense_buffer;
                                 /* obtained by REQUEST SENSE when
                                  * CHECK CONDITION is received on original
                                  * command (auto-sense) */