On 2025/2/12 1:24, Bart Van Assche wrote:
On 2/10/25 6:03 AM, Ye Bin wrote:
From: Ye Bin <yebin10@xxxxxxxxxx>
After commit 1bad6c4a57ef
("scsi: zero per-cmd private driver data for each MQ I/O"),
xen-scsifront/virtio_scsi/snic driver remove code that zeroes
driver-private command data. If request do retry will lead to
driver-private command data remains. Before commit 464a00c9e0ad
("scsi: core: Kill DRIVER_SENSE") if virtio_scsi do capacity
expansion, first request may return UA then request will do retry,
as driver-private command data remains, request will return UA
again. As a result, the request keeps retrying, and the request
times out and fails.
So zeroes driver-private command data when request do retry.
Fixes: f7de50da1479 ("scsi: xen-scsifront: Remove code that zeroes
driver-private command data")
Fixes: c2bb87318baa ("scsi: virtio_scsi: Remove code that zeroes
driver-private command data")
Fixes: c3006a926468 ("scsi: snic: Remove code that zeroes
driver-private command data")
Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx>
---
drivers/scsi/scsi_lib.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index be0890e4e706..5b0c109c89bb 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1645,6 +1645,17 @@ static unsigned int
scsi_mq_inline_sgl_size(struct Scsi_Host *shost)
sizeof(struct scatterlist);
}
+static inline void scsi_clear_lld_private_data(struct scsi_cmnd *cmd,
+ struct Scsi_Host *shost)
+{
+ /*
+ * Only clear the driver-private command data if the LLD does not
supply
+ * a function to initialize that data.
+ */
+ if (!shost->hostt->init_cmd_priv && shost->hostt->cmd_size)
+ memset(cmd + 1, 0, shost->hostt->cmd_size);
+}
+
static blk_status_t scsi_prepare_cmd(struct request *req)
{
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
@@ -1669,12 +1680,7 @@ static blk_status_t scsi_prepare_cmd(struct
request *req)
if (in_flight)
__set_bit(SCMD_STATE_INFLIGHT, &cmd->state);
- /*
- * Only clear the driver-private command data if the LLD does not
supply
- * a function to initialize that data.
- */
- if (!shost->hostt->init_cmd_priv)
- memset(cmd + 1, 0, shost->hostt->cmd_size);
+ scsi_clear_lld_private_data(cmd, shost);
cmd->prot_op = SCSI_PROT_NORMAL;
if (blk_rq_bytes(req))
@@ -1848,6 +1854,7 @@ static blk_status_t scsi_queue_rq(struct
blk_mq_hw_ctx *hctx,
goto out_dec_host_busy;
req->rq_flags |= RQF_DONTPREP;
} else {
+ scsi_clear_lld_private_data(cmd, shost);
clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
}
Thanks for the detailed analysis. Has the following (untested) simpler
alternative been considered?
Thank you for your reply.
I've considered your modification plan, but I think it's a little hard
to understand and the code feels a little loose. Of course, it's just my
own idea.
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index d776f13cd160..6ee2903b4adb 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1664,13 +1664,6 @@ static blk_status_t scsi_prepare_cmd(struct
request *req)
if (in_flight)
__set_bit(SCMD_STATE_INFLIGHT, &cmd->state);
- /*
- * Only clear the driver-private command data if the LLD does not
supply
- * a function to initialize that data.
- */
- if (!shost->hostt->init_cmd_priv)
- memset(cmd + 1, 0, shost->hostt->cmd_size);
-
cmd->prot_op = SCSI_PROT_NORMAL;
if (blk_rq_bytes(req))
cmd->sc_data_direction = rq_dma_dir(req);
@@ -1837,6 +1830,13 @@ static blk_status_t scsi_queue_rq(struct
blk_mq_hw_ctx *hctx,
if (!scsi_host_queue_ready(q, shost, sdev, cmd))
goto out_dec_target_busy;
+ /*
+ * Only clear the driver-private command data if the LLD does not
supply
+ * a function to initialize that data.
+ */
+ if (!shost->hostt->init_cmd_priv && shost->hostt->cmd_size)
+ memset(scsi_cmd_priv(cmd), 0, shost->hostt->cmd_size);
+
if (!(req->rq_flags & RQF_DONTPREP)) {
ret = scsi_prepare_cmd(req);
if (ret != BLK_STS_OK)
