From 98db519573e805f9f7e988fb5661da951fcb16b1 Mon Sep 17 00:00:00 2001
From: James Bottomley <James.Bottomley@suse.de>
Date: Mon, 25 Oct 2010 15:53:41 -0500
Subject: [PATCH] [SCSI] fix id computation in scsi_eh_target_reset()

The current code in scsi_eh_target_reset() has an off by one error
that actually sends spurious extra resets.  Since there's no real need
to reset the targets in numerical order, simply chunk up the command
recovery list doing target resets and pulling matching targets out of
the list (that also makes the loop O(N) instead of O(N^2).

[mike christie found and fixed a list_splice -> list_splice_init problem]

Reported-by: Hillf Danton<dhillf@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
---
 drivers/scsi/scsi_error.c | 61 ++++++++++++++++-----------------------
 1 file changed, 25 insertions(+), 36 deletions(-)

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 30ac116186f5..45c75649b9e0 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -1124,51 +1124,40 @@ static int scsi_eh_target_reset(struct Scsi_Host *shost,
 				struct list_head *work_q,
 				struct list_head *done_q)
 {
-	struct scsi_cmnd *scmd, *tgtr_scmd, *next;
-	unsigned int id = 0;
-	int rtn;
+	LIST_HEAD(tmp_list);
 
-	do {
-		tgtr_scmd = NULL;
-		list_for_each_entry(scmd, work_q, eh_entry) {
-			if (id == scmd_id(scmd)) {
-				tgtr_scmd = scmd;
-				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)
-			/* no more commands, that's it */
-			break;
+	list_splice_init(work_q, &tmp_list);
+
+	while (!list_empty(&tmp_list)) {
+		struct scsi_cmnd *next, *scmd;
+		int rtn;
+		unsigned int id;
+
+		scmd = list_entry(tmp_list.next, struct scsi_cmnd, eh_entry);
+		id = scmd_id(scmd);
 
 		SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending target reset "
 						  "to target %d\n",
 						  current->comm, id));
-		rtn = scsi_try_target_reset(tgtr_scmd);
-		if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
-			list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
-				if (id == scmd_id(scmd))
-					if (!scsi_device_online(scmd->device) ||
-					    rtn == FAST_IO_FAIL ||
-					    !scsi_eh_tur(tgtr_scmd))
-						scsi_eh_finish_cmd(scmd,
-								   done_q);
-			}
-		} else
+		rtn = scsi_try_target_reset(scmd);
+		if (rtn != SUCCESS && rtn != FAST_IO_FAIL)
 			SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Target reset"
 							  " failed target: "
 							  "%d\n",
 							  current->comm, id));
-		id++;
-	} while(id != 0);
+		list_for_each_entry_safe(scmd, next, &tmp_list, eh_entry) {
+			if (scmd_id(scmd) != id)
+				continue;
+
+			if ((rtn == SUCCESS || rtn == FAST_IO_FAIL)
+			    && (!scsi_device_online(scmd->device) ||
+				 rtn == FAST_IO_FAIL || !scsi_eh_tur(scmd)))
+				scsi_eh_finish_cmd(scmd, done_q);
+			else
+				/* push back on work queue for further processing */
+				list_move(&scmd->eh_entry, work_q);
+		}
+	}
 
 	return list_empty(work_q);
 }
-- 
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