Commit 832889f5ed45ec90c76f6eb97e64baf845929007
Committed by
Martin K. Petersen
Martin K. Petersen
1 parent
64104f7032
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>
Showing 1 changed file with 13 additions and 2 deletions Side-by-side Diff
drivers/scsi/scsi_lib.c
| ... | ... | @@ -1112,9 +1112,13 @@ |
| 1112 | 1112 | EXPORT_SYMBOL(scsi_init_io); |
| 1113 | 1113 | |
| 1114 | 1114 | /** |
| 1115 | - * scsi_initialize_rq - initialize struct scsi_cmnd.req | |
| 1115 | + * scsi_initialize_rq - initialize struct scsi_cmnd partially | |
| 1116 | 1116 | * @rq: Request associated with the SCSI command to be initialized. |
| 1117 | 1117 | * |
| 1118 | + * This function initializes the members of struct scsi_cmnd that must be | |
| 1119 | + * initialized before request processing starts and that won't be | |
| 1120 | + * reinitialized if a SCSI command is requeued. | |
| 1121 | + * | |
| 1118 | 1122 | * Called from inside blk_get_request() for pass-through requests and from |
| 1119 | 1123 | * inside scsi_init_command() for filesystem requests. |
| 1120 | 1124 | */ |
| ... | ... | @@ -1123,6 +1127,8 @@ |
| 1123 | 1127 | struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq); |
| 1124 | 1128 | |
| 1125 | 1129 | scsi_req_init(&cmd->req); |
| 1130 | + cmd->jiffies_at_alloc = jiffies; | |
| 1131 | + cmd->retries = 0; | |
| 1126 | 1132 | } |
| 1127 | 1133 | EXPORT_SYMBOL(scsi_initialize_rq); |
| 1128 | 1134 | |
| 1129 | 1135 | |
| ... | ... | @@ -1162,12 +1168,16 @@ |
| 1162 | 1168 | void *prot = cmd->prot_sdb; |
| 1163 | 1169 | struct request *rq = blk_mq_rq_from_pdu(cmd); |
| 1164 | 1170 | unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS; |
| 1171 | + unsigned long jiffies_at_alloc; | |
| 1172 | + int retries; | |
| 1165 | 1173 | |
| 1166 | 1174 | if (!blk_rq_is_scsi(rq) && !(flags & SCMD_INITIALIZED)) { |
| 1167 | 1175 | flags |= SCMD_INITIALIZED; |
| 1168 | 1176 | scsi_initialize_rq(rq); |
| 1169 | 1177 | } |
| 1170 | 1178 | |
| 1179 | + jiffies_at_alloc = cmd->jiffies_at_alloc; | |
| 1180 | + retries = cmd->retries; | |
| 1171 | 1181 | /* zero out the cmd, except for the embedded scsi_request */ |
| 1172 | 1182 | memset((char *)cmd + sizeof(cmd->req), 0, |
| 1173 | 1183 | sizeof(*cmd) - sizeof(cmd->req) + dev->host->hostt->cmd_size); |
| ... | ... | @@ -1177,7 +1187,8 @@ |
| 1177 | 1187 | cmd->prot_sdb = prot; |
| 1178 | 1188 | cmd->flags = flags; |
| 1179 | 1189 | INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler); |
| 1180 | - cmd->jiffies_at_alloc = jiffies; | |
| 1190 | + cmd->jiffies_at_alloc = jiffies_at_alloc; | |
| 1191 | + cmd->retries = retries; | |
| 1181 | 1192 | |
| 1182 | 1193 | scsi_add_cmd_to_list(cmd); |
| 1183 | 1194 | } |