Limit lifetime of scsi commands receiving DID_RESET status.
Signed-off-by: Michael Reed <mdr@xxxxxxx>
Limit lifetime of scsi commands receiving DID_RESET status.
Signed-off-by: Michael Reed <mdr@xxxxxxx>
--- rg61u/include/scsi/scsi.h 2006-10-31 21:08:47.000000000 -0600
+++ rg61/include/scsi/scsi.h 2007-01-29 15:58:40.633779567 -0600
@@ -353,6 +353,7 @@ struct scsi_lun {
#define SCSI_MLQUEUE_HOST_BUSY 0x1055
#define SCSI_MLQUEUE_DEVICE_BUSY 0x1056
#define SCSI_MLQUEUE_EH_RETRY 0x1057
+#define SCSI_MLQUEUE_DID_RESET 0x1058
/*
* Use these to separate status msg and our bytes
--- rg61u/drivers/scsi/scsi_lib.c 2007-01-29 15:11:11.466213588 -0600
+++ rg61/drivers/scsi/scsi_lib.c 2007-01-29 15:58:40.637779387 -0600
@@ -101,10 +101,10 @@ static void scsi_unprep_request(struct r
*
* Returns: Nothing.
*
- * Notes: We do this for one of two cases. Either the host is busy
+ * Notes: We do this for one of three cases. 1) the host is busy
* and it cannot accept any more commands for the time being,
- * or the device returned QUEUE_FULL and can accept no more
- * commands.
+ * 2) the device returned QUEUE_FULL and can accept no more
+ * commands, or 3) the LLDD returned DID_RESET.
* Notes: This could be called either from an interrupt context or a
* normal process context.
*/
@@ -138,9 +138,11 @@ int scsi_queue_insert(struct scsi_cmnd *
/*
* Decrement the counters, since these commands are no longer
- * active on the host/device.
+ * active on the host/device. If the reason is SCSI_MLQUEUE_DID_RESET
+ * then scsi_device_unbusy() was called by scsi_finish_command().
*/
- scsi_device_unbusy(device);
+ if (reason != SCSI_MLQUEUE_DID_RESET)
+ scsi_device_unbusy(device);
/*
* Requeue this command. It will go before all other commands
@@ -792,6 +794,33 @@ static void scsi_release_buffers(struct
}
/*
+ * Function: scsi_command_expired()
+ *
+ * Purpose: Check scsi a command's age before retrying it.
+ *
+ * Arguments: cmd - command that we are checking for timeout.
+ *
+ * Returns: non-zero if command has exceeded its lifetime
+ * zero otherwise
+ *
+ * Notes: A command's lifetime is considered to be the number
+ * of (retries permitted plus one) * command timeout.
+ *
+ */
+static int scsi_command_expired(struct scsi_cmnd *cmd)
+{
+ int ret = 0;
+ unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command;
+ if (time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
+ sdev_printk(KERN_ERR, cmd->device,
+ "timing out command, waited %lus\n",
+ wait_for/HZ);
+ ret = 1;
+ }
+ return ret;
+}
+
+/*
* Function: scsi_io_completion()
*
* Purpose: Completion processing for block device I/O requests.
@@ -962,12 +991,26 @@ void scsi_io_completion(struct scsi_cmnd
}
}
if (host_byte(result) == DID_RESET) {
- /* Third party bus reset or reset for error recovery
- * reasons. Just retry the request and see what
- * happens.
+ /*
+ * Third party bus reset or reset for error recovery reasons.
+ * If no data was transferred and the command has not expired,
+ * just reinsert the command on the queue. If the command
+ * HAS expired, we fall through to call scsi_end_request.
+ *
+ * If data was transferred, regenerate the command to transfer
+ * only untransferred data by calling scsi_requeue_command().
*/
- scsi_requeue_command(q, cmd);
- return;
+ if (!good_bytes) {
+ if (!(scsi_command_expired(cmd))) {
+ scsi_queue_insert(cmd, SCSI_MLQUEUE_DID_RESET);
+ return;
+ }
+ /* fall through to call scsi_end_request() */
+ }
+ else {
+ scsi_requeue_command(q, cmd);
+ return;
+ }
}
if (result) {
if (!(req->cmd_flags & REQ_QUIET)) {
@@ -1381,17 +1424,12 @@ static void scsi_kill_request(struct req
static void scsi_softirq_done(struct request *rq)
{
struct scsi_cmnd *cmd = rq->completion_data;
- unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command;
int disposition;
INIT_LIST_HEAD(&cmd->eh_entry);
disposition = scsi_decide_disposition(cmd);
- if (disposition != SUCCESS &&
- time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
- sdev_printk(KERN_ERR, cmd->device,
- "timing out command, waited %lus\n",
- wait_for/HZ);
+ if (disposition != SUCCESS && scsi_command_expired(cmd)) {
disposition = SUCCESS;
}
