diff options
| author | Bart Van Assche <bart.vanassche@wdc.com> | 2017-08-30 16:58:40 -0700 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2017-08-31 23:07:49 -0400 |
| commit | 832889f5ed45ec90c76f6eb97e64baf845929007 (patch) | |
| tree | bd841e01a8b28d9000bfd2930ad74918b6100c17 /drivers/scsi | |
| parent | 64104f703212ff50e855bb2e2fa80d71db62c521 (diff) | |
| download | linux-832889f5ed45ec90c76f6eb97e64baf845929007.tar.bz2 | |
scsi: Improve requeuing behavior
Requests are unprepared and reprepared when being requeued. Avoid that
requeuing resets .jiffies_at_alloc and .retries by initializing these
two member variables from inside scsi_initialize_rq() and by preserving
both member variables when preparing a request. This patch affects the
requeuing behavior of both the legacy scsi and the scsi-mq code paths.
Reported-by: Brian King <brking@linux.vnet.ibm.com>
References: https://lkml.org/lkml/2017/8/18/923 ("Re: [BUG][bisected 270065e] linux-next fails to boot on powerpc")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Brian King <brking@linux.vnet.ibm.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi')
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 4bfe0df35823..6085377643ae 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1112,9 +1112,13 @@ err_exit: EXPORT_SYMBOL(scsi_init_io); /** - * scsi_initialize_rq - initialize struct scsi_cmnd.req + * scsi_initialize_rq - initialize struct scsi_cmnd partially * @rq: Request associated with the SCSI command to be initialized. * + * This function initializes the members of struct scsi_cmnd that must be + * initialized before request processing starts and that won't be + * reinitialized if a SCSI command is requeued. + * * Called from inside blk_get_request() for pass-through requests and from * inside scsi_init_command() for filesystem requests. */ @@ -1123,6 +1127,8 @@ void scsi_initialize_rq(struct request *rq) struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq); scsi_req_init(&cmd->req); + cmd->jiffies_at_alloc = jiffies; + cmd->retries = 0; } EXPORT_SYMBOL(scsi_initialize_rq); @@ -1162,12 +1168,16 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd) void *prot = cmd->prot_sdb; struct request *rq = blk_mq_rq_from_pdu(cmd); unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS; + unsigned long jiffies_at_alloc; + int retries; if (!blk_rq_is_scsi(rq) && !(flags & SCMD_INITIALIZED)) { flags |= SCMD_INITIALIZED; scsi_initialize_rq(rq); } + jiffies_at_alloc = cmd->jiffies_at_alloc; + retries = cmd->retries; /* 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); @@ -1177,7 +1187,8 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd) cmd->prot_sdb = prot; cmd->flags = flags; INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler); - cmd->jiffies_at_alloc = jiffies; + cmd->jiffies_at_alloc = jiffies_at_alloc; + cmd->retries = retries; scsi_add_cmd_to_list(cmd); } |