From: Christoph Hellwig <hch@xxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit 15e3d5a285ab9283136dba34bbf72886d9146706 upstream.
3w controller don't dma map small single SGL entry commands but instead
bounce buffer them. Add a helper to identify these commands and don't
call scsi_dma_unmap for them.
Based on an earlier patch from James Bottomley.
Fixes: 118c85 ("3w-9xxx: fix command completion race")
Reported-by: Tóth Attila <atoth@xxxxxxxxxxxxx>
Tested-by: Tóth Attila <atoth@xxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Acked-by: Adam Radford <aradford@xxxxxxxxx>
Signed-off-by: James Bottomley <JBottomley@xxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
drivers/scsi/3w-9xxx.c | 28 +++++++++++++++++++++-------
1 file changed, 21 insertions(+), 7 deletions(-)
diff --git a/drivers/scsi/3w-9xxx.c b/drivers/scsi/3w-9xxx.c
index 5f57e3d35e26..6adf9abdf955 100644
--- a/drivers/scsi/3w-9xxx.c
+++ b/drivers/scsi/3w-9xxx.c
@@ -225,6 +225,17 @@ static const struct file_operations twa_fops = {
.llseek = noop_llseek,
};
+/*
+ * The controllers use an inline buffer instead of a mapped SGL for small,
+ * single entry buffers. Note that we treat a zero-length transfer like
+ * a mapped SGL.
+ */
+static bool twa_command_mapped(struct scsi_cmnd *cmd)
+{
+ return scsi_sg_count(cmd) != 1 ||
+ scsi_bufflen(cmd) >= TW_MIN_SGL_LENGTH;
+}
+
/* This function will complete an aen request from the isr */
static int twa_aen_complete(TW_Device_Extension *tw_dev, int request_id)
{
@@ -1351,7 +1362,8 @@ static irqreturn_t twa_interrupt(int irq, void *dev_instance)
}
/* Now complete the io */
- scsi_dma_unmap(cmd);
+ if (twa_command_mapped(cmd))
+ scsi_dma_unmap(cmd);
cmd->scsi_done(cmd);
tw_dev->state[request_id] = TW_S_COMPLETED;
twa_free_request_id(tw_dev, request_id);
@@ -1594,7 +1606,8 @@ static int twa_reset_device_extension(TW_Device_Extension *tw_dev)
struct scsi_cmnd *cmd = tw_dev->srb[i];
cmd->result = (DID_RESET << 16);
- scsi_dma_unmap(cmd);
+ if (twa_command_mapped(cmd))
+ scsi_dma_unmap(cmd);
cmd->scsi_done(cmd);
}
}
@@ -1777,12 +1790,14 @@ static int twa_scsi_queue_lck(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_
retval = twa_scsiop_execute_scsi(tw_dev, request_id, NULL, 0, NULL);
switch (retval) {
case SCSI_MLQUEUE_HOST_BUSY:
- scsi_dma_unmap(SCpnt);
+ if (twa_command_mapped(SCpnt))
+ scsi_dma_unmap(SCpnt);
twa_free_request_id(tw_dev, request_id);
break;
case 1:
SCpnt->result = (DID_ERROR << 16);
- scsi_dma_unmap(SCpnt);
+ if (twa_command_mapped(SCpnt))
+ scsi_dma_unmap(SCpnt);
done(SCpnt);
tw_dev->state[request_id] = TW_S_COMPLETED;
twa_free_request_id(tw_dev, request_id);
@@ -1843,8 +1858,7 @@ static int twa_scsiop_execute_scsi(TW_Device_Extension *tw_dev, int request_id,
/* Map sglist from scsi layer to cmd packet */
if (scsi_sg_count(srb)) {
- if ((scsi_sg_count(srb) == 1) &&
- (scsi_bufflen(srb) < TW_MIN_SGL_LENGTH)) {
+ if (!twa_command_mapped(srb)) {
if (srb->sc_data_direction == DMA_TO_DEVICE ||
srb->sc_data_direction == DMA_BIDIRECTIONAL)
scsi_sg_copy_to_buffer(srb,
@@ -1917,7 +1931,7 @@ static void twa_scsiop_execute_scsi_complete(TW_Device_Extension *tw_dev, int re
{
struct scsi_cmnd *cmd = tw_dev->srb[request_id];
- if (scsi_bufflen(cmd) < TW_MIN_SGL_LENGTH &&
+ if (!twa_command_mapped(cmd) &&
(cmd->sc_data_direction == DMA_FROM_DEVICE ||
cmd->sc_data_direction == DMA_BIDIRECTIONAL)) {
if (scsi_sg_count(cmd) == 1) {
--
2.6.2
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html