[PATCH 1/6] ncr5380: Correctly clear command pointers and lists after bus reset

[Finn Thain]

Commands subject to exception handling are to be returned to the scsi
mid-layer. Make sure that the various command pointers and command lists
in the low-level driver are correctly cleansed of affected commands.

This fixes some bugs that I accidentally introduced in v4.5-rc1 including
the removal of INIT_LIST_HEAD for the 'autosense' and 'disconnected'
command lists, and the possible NULL pointer dereference in
NCR5380_bus_reset() that was reported by Dan Carpenter.

hostdata->sensing may also point to an affected command so this pointer
also has to be cleared. The abort handler calls complete_cmd() to take
care of this; let's have the bus reset handler do the same.

The issue queue may also contain an affected command. If so, remove it.
This also follows the abort handler logic.

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Fixes: 62717f537e1b ("ncr5380: Implement new eh_bus_reset_handler")
Tested-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>

---
 drivers/scsi/NCR5380.c       |   19 ++++++++++++-------
 drivers/scsi/atari_NCR5380.c |   19 ++++++++++++-------
 2 files changed, 24 insertions(+), 14 deletions(-)

Index: linux/drivers/scsi/NCR5380.c
===================================================================
--- linux.orig/drivers/scsi/NCR5380.c	2016-02-23 10:06:56.000000000 +1100
+++ linux/drivers/scsi/NCR5380.c	2016-02-23 10:06:56.000000000 +1100
@@ -2450,7 +2450,16 @@ static int NCR5380_bus_reset(struct scsi
 	 * commands!
 	 */
 
-	hostdata->selecting = NULL;
+	if (list_del_cmd(&hostdata->unissued, cmd)) {
+		cmd->result = DID_RESET << 16;
+		cmd->scsi_done(cmd);
+	}
+
+	if (hostdata->selecting) {
+		hostdata->selecting->result = DID_RESET << 16;
+		complete_cmd(instance, hostdata->selecting);
+		hostdata->selecting = NULL;
+	}
 
 	list_for_each_entry(ncmd, &hostdata->disconnected, list) {
 		struct scsi_cmnd *cmd = NCR5380_to_scmd(ncmd);
@@ -2458,6 +2467,7 @@ static int NCR5380_bus_reset(struct scsi
 		set_host_byte(cmd, DID_RESET);
 		cmd->scsi_done(cmd);
 	}
+	INIT_LIST_HEAD(&hostdata->disconnected);
 
 	list_for_each_entry(ncmd, &hostdata->autosense, list) {
 		struct scsi_cmnd *cmd = NCR5380_to_scmd(ncmd);
@@ -2465,6 +2475,7 @@ static int NCR5380_bus_reset(struct scsi
 		set_host_byte(cmd, DID_RESET);
 		cmd->scsi_done(cmd);
 	}
+	INIT_LIST_HEAD(&hostdata->autosense);
 
 	if (hostdata->connected) {
 		set_host_byte(hostdata->connected, DID_RESET);
@@ -2472,12 +2483,6 @@ static int NCR5380_bus_reset(struct scsi
 		hostdata->connected = NULL;
 	}
 
-	if (hostdata->sensing) {
-		set_host_byte(hostdata->connected, DID_RESET);
-		complete_cmd(instance, hostdata->sensing);
-		hostdata->sensing = NULL;
-	}
-
 	for (i = 0; i < 8; ++i)
 		hostdata->busy[i] = 0;
 #ifdef REAL_DMA
Index: linux/drivers/scsi/atari_NCR5380.c
===================================================================
--- linux.orig/drivers/scsi/atari_NCR5380.c	2016-02-23 10:06:56.000000000 +1100
+++ linux/drivers/scsi/atari_NCR5380.c	2016-02-23 10:06:56.000000000 +1100
@@ -2646,7 +2646,16 @@ static int NCR5380_bus_reset(struct scsi
 	 * commands!
 	 */
 
-	hostdata->selecting = NULL;
+	if (list_del_cmd(&hostdata->unissued, cmd)) {
+		cmd->result = DID_RESET << 16;
+		cmd->scsi_done(cmd);
+	}
+
+	if (hostdata->selecting) {
+		hostdata->selecting->result = DID_RESET << 16;
+		complete_cmd(instance, hostdata->selecting);
+		hostdata->selecting = NULL;
+	}
 
 	list_for_each_entry(ncmd, &hostdata->disconnected, list) {
 		struct scsi_cmnd *cmd = NCR5380_to_scmd(ncmd);
@@ -2654,6 +2663,7 @@ static int NCR5380_bus_reset(struct scsi
 		set_host_byte(cmd, DID_RESET);
 		cmd->scsi_done(cmd);
 	}
+	INIT_LIST_HEAD(&hostdata->disconnected);
 
 	list_for_each_entry(ncmd, &hostdata->autosense, list) {
 		struct scsi_cmnd *cmd = NCR5380_to_scmd(ncmd);
@@ -2661,6 +2671,7 @@ static int NCR5380_bus_reset(struct scsi
 		set_host_byte(cmd, DID_RESET);
 		cmd->scsi_done(cmd);
 	}
+	INIT_LIST_HEAD(&hostdata->autosense);
 
 	if (hostdata->connected) {
 		set_host_byte(hostdata->connected, DID_RESET);
@@ -2668,12 +2679,6 @@ static int NCR5380_bus_reset(struct scsi
 		hostdata->connected = NULL;
 	}
 
-	if (hostdata->sensing) {
-		set_host_byte(hostdata->connected, DID_RESET);
-		complete_cmd(instance, hostdata->sensing);
-		hostdata->sensing = NULL;
-	}
-
 #ifdef SUPPORT_TAGS
 	free_all_tags(hostdata);
 #endif