Commit 832889f5 authored by Bart Van Assche's avatar Bart Van Assche Committed by Martin K. Petersen

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: default avatarBrian 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: default avatarBart 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: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 64104f70
...@@ -1112,9 +1112,13 @@ int scsi_init_io(struct scsi_cmnd *cmd) ...@@ -1112,9 +1112,13 @@ int scsi_init_io(struct scsi_cmnd *cmd)
EXPORT_SYMBOL(scsi_init_io); 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. * @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 * Called from inside blk_get_request() for pass-through requests and from
* inside scsi_init_command() for filesystem requests. * inside scsi_init_command() for filesystem requests.
*/ */
...@@ -1123,6 +1127,8 @@ void scsi_initialize_rq(struct request *rq) ...@@ -1123,6 +1127,8 @@ void scsi_initialize_rq(struct request *rq)
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq); struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
scsi_req_init(&cmd->req); scsi_req_init(&cmd->req);
cmd->jiffies_at_alloc = jiffies;
cmd->retries = 0;
} }
EXPORT_SYMBOL(scsi_initialize_rq); EXPORT_SYMBOL(scsi_initialize_rq);
...@@ -1162,12 +1168,16 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd) ...@@ -1162,12 +1168,16 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
void *prot = cmd->prot_sdb; void *prot = cmd->prot_sdb;
struct request *rq = blk_mq_rq_from_pdu(cmd); struct request *rq = blk_mq_rq_from_pdu(cmd);
unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS; unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS;
unsigned long jiffies_at_alloc;
int retries;
if (!blk_rq_is_scsi(rq) && !(flags & SCMD_INITIALIZED)) { if (!blk_rq_is_scsi(rq) && !(flags & SCMD_INITIALIZED)) {
flags |= SCMD_INITIALIZED; flags |= SCMD_INITIALIZED;
scsi_initialize_rq(rq); scsi_initialize_rq(rq);
} }
jiffies_at_alloc = cmd->jiffies_at_alloc;
retries = cmd->retries;
/* zero out the cmd, except for the embedded scsi_request */ /* zero out the cmd, except for the embedded scsi_request */
memset((char *)cmd + sizeof(cmd->req), 0, memset((char *)cmd + sizeof(cmd->req), 0,
sizeof(*cmd) - sizeof(cmd->req) + dev->host->hostt->cmd_size); 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) ...@@ -1177,7 +1187,8 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
cmd->prot_sdb = prot; cmd->prot_sdb = prot;
cmd->flags = flags; cmd->flags = flags;
INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler); 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); scsi_add_cmd_to_list(cmd);
} }
......
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