The current behavior of the SCSI core is to clear driver-private data
before preparing a request for submission to the SCSI LLD. Make it possible
for SCSI LLDs to disable clearing of driver-private data.
These hooks will be used by a later patch, namely "ufs: Let the SCSI core
allocate per-command UFS data".
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Johannes Thumshirn <jth@xxxxxxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Can Guo <cang@xxxxxxxxxxxxxx>
Cc: Avri Altman <avri.altman@xxxxxxx>
Cc: Bean Huo <beanhuo@xxxxxxxxxx>
Cc: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
Cc: Tomas Winkler <tomas.winkler@xxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
drivers/scsi/scsi_lib.c | 29 +++++++++++++++++++++++------
include/scsi/scsi_host.h | 3 +++
2 files changed, 26 insertions(+), 6 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 97af9bf54b22..f0ea614ee49b 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1127,7 +1127,7 @@ void scsi_del_cmd_from_list(struct scsi_cmnd *cmd)
}
}
-/* Called after a request has been started. */
+/* Called before a request is prepared. See also scsi_mq_prep_fn(). */
void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
{
void *buf = cmd->sense_buffer;
@@ -1135,7 +1135,7 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
struct request *rq = blk_mq_rq_from_pdu(cmd);
unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS;
unsigned long jiffies_at_alloc;
- int retries;
+ int retries, to_clear;
bool in_flight;
if (!blk_rq_is_scsi(rq) && !(flags & SCMD_INITIALIZED)) {
@@ -1146,9 +1146,15 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
jiffies_at_alloc = cmd->jiffies_at_alloc;
retries = cmd->retries;
in_flight = test_bit(SCMD_STATE_INFLIGHT, &cmd->state);
- /* zero out the cmd, except for the embedded scsi_request */
- memset((char *)cmd + sizeof(cmd->req), 0,
- sizeof(*cmd) - sizeof(cmd->req) + dev->host->hostt->cmd_size);
+ /*
+ * Zero out the cmd, except for the embedded scsi_request. Only clear
+ * the driver-private command data if the LLD does not supply a
+ * function to initialize that data.
+ */
+ to_clear = sizeof(*cmd) - sizeof(cmd->req);
+ if (!dev->host->hostt->init_cmd_priv)
+ to_clear += dev->host->hostt->cmd_size;
+ memset((char *)cmd + sizeof(cmd->req), 0, to_clear);
cmd->device = dev;
cmd->sense_buffer = buf;
@@ -1742,6 +1748,7 @@ static int scsi_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
const bool unchecked_isa_dma = shost->unchecked_isa_dma;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
struct scatterlist *sg;
+ int ret = 0;
if (unchecked_isa_dma)
cmd->flags |= SCMD_UNCHECKED_ISA_DMA;
@@ -1757,14 +1764,24 @@ static int scsi_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
cmd->prot_sdb = (void *)sg + scsi_mq_inline_sgl_size(shost);
}
- return 0;
+ if (shost->hostt->init_cmd_priv) {
+ ret = shost->hostt->init_cmd_priv(shost, cmd);
+ if (ret < 0)
+ scsi_free_sense_buffer(unchecked_isa_dma,
+ cmd->sense_buffer);
+ }
+
+ return ret;
}
static void scsi_mq_exit_request(struct blk_mq_tag_set *set, struct request *rq,
unsigned int hctx_idx)
{
+ struct Scsi_Host *shost = set->driver_data;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
+ if (shost->hostt->exit_cmd_priv)
+ shost->hostt->exit_cmd_priv(shost, cmd);
scsi_free_sense_buffer(cmd->flags & SCMD_UNCHECKED_ISA_DMA,
cmd->sense_buffer);
}
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index f577647bf5f2..1fa81f9b063f 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -62,6 +62,9 @@ struct scsi_host_template {
void __user *arg);
#endif
+ int (*init_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd);
+ int (*exit_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd);
+
/*
* The queuecommand function is used to queue up a scsi
* command block to the LLDD. When the driver finished
