[SCSI] use one-element sg list in scsi_send_eh_cmnd

scsi_send_eh_cmnd is the last user of non-sg commands currently.
This patch switches it to a one-element SG list.  Also updates the
kerneldoc comment for scsi_send_eh_cmnd to reflect reality while we're
at it.

Test on my mptsas card, but this should get testing with as many
drivers as possible.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index aff1b0cfd4b25bfcdf2ceda22e6d522969d7ab9b..2ecb6ff42444697d9aa866de4bb00c0d707880b5 100644 (file)
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -453,9 +453,18 @@ static void scsi_eh_done(struct scsi_cmnd *scmd)
 }
 
 /**
- * scsi_send_eh_cmnd  - send a cmd to a device as part of error recovery.
- * @scmd:      SCSI Cmd to send.
- * @timeout:   Timeout for cmd.
+ * scsi_send_eh_cmnd  - submit a scsi command as part of error recory
+ * @scmd:       SCSI command structure to hijack
+ * @cmnd:       CDB to send
+ * @cmnd_size:  size in bytes of @cmnd
+ * @timeout:    timeout for this request
+ * @copy_sense: request sense data if set to 1
+ *
+ * This function is used to send a scsi command down to a target device
+ * as part of the error recovery process.  If @copy_sense is 0 the command
+ * sent must be one that does not transfer any data.  If @copy_sense is 1
+ * the command must be REQUEST_SENSE and this functions copies out the
+ * sense buffer it got into @scmd->sense_buffer.
  *
  * Return value:
  *    SUCCESS or FAILED or NEEDS_RETRY
@@ -469,6 +478,7 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
        DECLARE_COMPLETION_ONSTACK(done);
        unsigned long timeleft;
        unsigned long flags;
+       struct scatterlist sgl;
        unsigned char old_cmnd[MAX_COMMAND_SIZE];
        enum dma_data_direction old_data_direction;
        unsigned short old_use_sg;
@@ -500,19 +510,24 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
                if (shost->hostt->unchecked_isa_dma)
                        gfp_mask |= __GFP_DMA;
 
-               scmd->sc_data_direction = DMA_FROM_DEVICE;
-               scmd->request_bufflen = 252;
-               scmd->request_buffer = kzalloc(scmd->request_bufflen, gfp_mask);
-               if (!scmd->request_buffer)
+               sgl.page = alloc_page(gfp_mask);
+               if (!sgl.page)
                        return FAILED;
+               sgl.offset = 0;
+               sgl.length = 252;
+
+               scmd->sc_data_direction = DMA_FROM_DEVICE;
+               scmd->request_bufflen = sgl.length;
+               scmd->request_buffer = &sgl;
+               scmd->use_sg = 1;
        } else {
                scmd->request_buffer = NULL;
                scmd->request_bufflen = 0;
                scmd->sc_data_direction = DMA_NONE;
+               scmd->use_sg = 0;
        }
 
        scmd->underflow = 0;
-       scmd->use_sg = 0;
        scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 
        if (sdev->scsi_level <= SCSI_2)
@@ -583,7 +598,7 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
                        memcpy(scmd->sense_buffer, scmd->request_buffer,
                               sizeof(scmd->sense_buffer));
                }
-               kfree(scmd->request_buffer);
+               __free_page(sgl.page);
        }