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Subject[PATCH RESEND 1/2] scsi: vmw_pvscsi: Fix swiotlb operation
Date
From: Thomas Hellstrom <thellstrom@vmware.com>

With swiotlb, the first byte of the sense buffer may in some cases be
uninitialized since we use DMA_FROM_DEVICE, and the device incorrectly
doesn't clear it. In those cases, clear it after DMA unmapping.

Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Suggested-by: Vishal Bhakta <vbhakta@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Acked-by: Jim Gill <jgill@vmware.com>
---
drivers/scsi/vmw_pvscsi.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/drivers/scsi/vmw_pvscsi.c b/drivers/scsi/vmw_pvscsi.c
index 70008816c91f..8a09d184a320 100644
--- a/drivers/scsi/vmw_pvscsi.c
+++ b/drivers/scsi/vmw_pvscsi.c
@@ -402,6 +402,17 @@ static int pvscsi_map_buffers(struct pvscsi_adapter *adapter,
return 0;
}

+/*
+ * The device incorrectly doesn't clear the first byte of the sense
+ * buffer in some cases. We have to do it ourselves.
+ * Otherwise we run into trouble when SWIOTLB is forced.
+ */
+static void pvscsi_patch_sense(struct scsi_cmnd *cmd)
+{
+ if (cmd->sense_buffer)
+ cmd->sense_buffer[0] = 0;
+}
+
static void pvscsi_unmap_buffers(const struct pvscsi_adapter *adapter,
struct pvscsi_ctx *ctx)
{
@@ -544,6 +555,8 @@ static void pvscsi_complete_request(struct pvscsi_adapter *adapter,
cmd = ctx->cmd;
abort_cmp = ctx->abort_cmp;
pvscsi_unmap_buffers(adapter, ctx);
+ if (sdstat != SAM_STAT_CHECK_CONDITION)
+ pvscsi_patch_sense(cmd);
pvscsi_release_context(adapter, ctx);
if (abort_cmp) {
/*
@@ -873,6 +886,7 @@ static void pvscsi_reset_all(struct pvscsi_adapter *adapter)
scmd_printk(KERN_ERR, cmd,
"Forced reset on cmd %p\n", cmd);
pvscsi_unmap_buffers(adapter, ctx);
+ pvscsi_patch_sense(cmd);
pvscsi_release_context(adapter, ctx);
cmd->result = (DID_RESET << 16);
cmd->scsi_done(cmd);
--
2.21.0
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