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scsi: core: Introduce {init,exit}_cmd_priv() 

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 "scsi: ufs: Let the SCSI
core allocate per-command UFS data".

Link: https://lore.kernel.org/r/20200123035637.21848-2-bvanassche@acm.org
Cc: Tomas Winkler <tomas.winkler@intel.com>
Cc: Stanley Chu <stanley.chu@mediatek.com>
Cc: Bean Huo <beanhuo@micron.com>
Cc: Avri Altman <avri.altman@wdc.com>
Cc: Can Guo <cang@codeaurora.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Johannes Thumshirn <jth@kernel.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Bart Van Assche 2020-01-22 19:56:34 -08:00 committed by Martin K. Petersen
parent c5a9707672
commit 65ca846a53
2 changed files with 26 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
drivers/scsi/scsi_lib.c
View File

@ -1097,7 +1097,7 @@ static void scsi_cleanup_rq(struct request *rq)
}
}
/* 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;
@ -1105,7 +1105,7 @@ 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)) {
@ -1116,9 +1116,15 @@ 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;
@ -1711,6 +1717,7 @@ 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;
@ -1726,14 +1733,24 @@ 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);
}

3
include/scsi/scsi_host.h
View File

@ -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