[SCSI] scsi_error: fix target reset handling
James Bottomley [Fri, 12 Sep 2008 21:46:51 +0000 (16:46 -0500)]
There's a target reset bug.

This loop:

for (id = 0; id <= shost->max_id; id++) {

Never terminates if shost->max_id is set to ~0, like aic94xx does.

It's also pretty inefficient since you mostly have compact target
numbers, but the max_id can be very high.  The best way would be to
sort the recovery list by target id and skip them if they're equal,
but even a worst case O(N^2) traversal is probably OK here, so fix it
by finding the next highest target number (assuming n+1) and
terminating when there isn't one.

Cc: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/scsi_error.c

index ad019ec..94ed262 100644 (file)
@@ -1065,10 +1065,10 @@ static int scsi_eh_target_reset(struct Scsi_Host *shost,
                                struct list_head *done_q)
 {
        struct scsi_cmnd *scmd, *tgtr_scmd, *next;
-       unsigned int id;
+       unsigned int id = 0;
        int rtn;
 
-       for (id = 0; id <= shost->max_id; id++) {
+       do {
                tgtr_scmd = NULL;
                list_for_each_entry(scmd, work_q, eh_entry) {
                        if (id == scmd_id(scmd)) {
@@ -1076,8 +1076,18 @@ static int scsi_eh_target_reset(struct Scsi_Host *shost,
                                break;
                        }
                }
+               if (!tgtr_scmd) {
+                       /* not one exactly equal; find the next highest */
+                       list_for_each_entry(scmd, work_q, eh_entry) {
+                               if (scmd_id(scmd) > id &&
+                                   (!tgtr_scmd ||
+                                    scmd_id(tgtr_scmd) > scmd_id(scmd)))
+                                               tgtr_scmd = scmd;
+                       }
+               }
                if (!tgtr_scmd)
-                       continue;
+                       /* no more commands, that's it */
+                       break;
 
                SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending target reset "
                                                  "to target %d\n",
@@ -1096,7 +1106,8 @@ static int scsi_eh_target_reset(struct Scsi_Host *shost,
                                                          " failed target: "
                                                          "%d\n",
                                                          current->comm, id));
-       }
+               id++;
+       } while(id != 0);
 
        return list_empty(work_q);
 }