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scsi: core: Don't memset() the entire scsi_cmnd in scsi_init_command()

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Replace the big fat memset that requires saving and restoring various
fields with just initializing those fields that need initialization.

All the clearing to 0 is moved to scsi_prepare_cmd() as scsi_ioctl_reset()
alreadly uses kzalloc() to allocate a pre-zeroed command.

This is still conservative and can probably be optimized further.

Link: https://lore.kernel.org/r/20220224175552.988286-3-hch@lst.de
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Christoph Hellwig 2022-02-24 18:55:46 +01:00 committed by Martin K. Petersen
parent c49ff72cff
commit 71bada345b
1 changed files with 27 additions and 31 deletions
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58
drivers/scsi/scsi_lib.c
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@ -1163,45 +1163,16 @@ static void scsi_cleanup_rq(struct request *rq)
/* 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;
void *prot = cmd->prot_sdb;
struct request *rq = scsi_cmd_to_rq(cmd);
unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS;
unsigned long jiffies_at_alloc;
int retries, to_clear;
bool in_flight;
int budget_token = cmd->budget_token;
if (!blk_rq_is_passthrough(rq) && !(flags & SCMD_INITIALIZED)) {
flags |= SCMD_INITIALIZED;
if (!blk_rq_is_passthrough(rq) && !(cmd->flags & SCMD_INITIALIZED)) {
cmd->flags |= SCMD_INITIALIZED;
scsi_initialize_rq(rq);
}
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. 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;
cmd->prot_sdb = prot;
cmd->flags = flags;
INIT_LIST_HEAD(&cmd->eh_entry);
INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
cmd->jiffies_at_alloc = jiffies_at_alloc;
cmd->retries = retries;
if (in_flight)
__set_bit(SCMD_STATE_INFLIGHT, &cmd->state);
cmd->budget_token = budget_token;
}
static blk_status_t scsi_setup_scsi_cmnd(struct scsi_device *sdev,
@ -1586,10 +1557,35 @@ static blk_status_t scsi_prepare_cmd(struct request *req)
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
struct scsi_device *sdev = req->q->queuedata;
struct Scsi_Host *shost = sdev->host;
bool in_flight = test_bit(SCMD_STATE_INFLIGHT, &cmd->state);
struct scatterlist *sg;
scsi_init_command(sdev, cmd);
cmd->eh_eflags = 0;
cmd->allowed = 0;
cmd->prot_type = 0;
cmd->prot_flags = 0;
cmd->submitter = 0;
cmd->cmd_len = 0;
cmd->cmnd = NULL;
memset(&cmd->sdb, 0, sizeof(cmd->sdb));
cmd->underflow = 0;
cmd->transfersize = 0;
cmd->host_scribble = NULL;
cmd->result = 0;
cmd->extra_len = 0;
cmd->state = 0;
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);