Scsi_Cmnd *last_cmnd;
static unsigned long serial_number;
-struct softscsi_data {
- Scsi_Cmnd *head;
- Scsi_Cmnd *tail;
-};
-
-static struct softscsi_data softscsi_data[NR_CPUS] __cacheline_aligned;
+static struct list_head done_q[NR_CPUS] __cacheline_aligned;
/*
* List of all highlevel drivers.
}
/**
- * scsi_done - Mark this command as done
- * @SCpnt: The SCSI Command which we think we've completed.
- *
- * This function is the mid-level interrupt routine, which decides how
- * to handle error conditions. Each invocation of this function must
- * do one and *only* one of the following:
+ * scsi_done - Enqueue the finished SCSI command into the done queue.
+ * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
+ * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
*
- * 1) Insert command in BH queue.
- * 2) Activate error handler for host.
+ * This function is the mid-level's (SCSI Core) interrupt routine, which
+ * regains ownership of the SCSI command (de facto) from a LLDD, and enqueues
+ * the command to the done queue for further processing.
*
- * There is no longer a problem with stack overflow. Interrupts queue
- * Scsi_Cmnd on a per-CPU queue and the softirq handler removes them
- * from the queue one at a time.
+ * This is the producer of the done queue who enqueues at the tail.
*
- * This function is sometimes called from interrupt context, but sometimes
- * from task context.
+ * This function is interrupt context safe.
*/
-void scsi_done(Scsi_Cmnd * SCpnt)
+void scsi_done(struct scsi_cmnd *cmd)
{
+ int cpu;
unsigned long flags;
- int cpu, tstatus;
- struct softscsi_data *queue;
+ struct list_head *pdone_q;
/*
* We don't have to worry about this one timing out any more.
- */
- tstatus = scsi_delete_timer(SCpnt);
-
- /*
- * If we are unable to remove the timer, it means that the command
- * has already timed out. In this case, we have no choice but to
+ * If we are unable to remove the timer, then the command
+ * has already timed out. In which case, we have no choice but to
* let the timeout function run, as we have no idea where in fact
* that function could really be. It might be on another processor,
* etc, etc.
*/
- if (!tstatus) {
+ if (!scsi_delete_timer(cmd))
return;
- }
/* Set the serial numbers back to zero */
- SCpnt->serial_number = 0;
- SCpnt->serial_number_at_timeout = 0;
- SCpnt->state = SCSI_STATE_BHQUEUE;
- SCpnt->owner = SCSI_OWNER_BH_HANDLER;
- SCpnt->bh_next = NULL;
+ cmd->serial_number = 0;
+ cmd->serial_number_at_timeout = 0;
+ cmd->state = SCSI_STATE_BHQUEUE;
+ cmd->owner = SCSI_OWNER_BH_HANDLER;
/*
- * Next, put this command in the softirq queue.
- *
- * This is a per-CPU queue, so we just disable local interrupts
+ * Next, enqueue the command into the done queue.
+ * It is a per-CPU queue, so we just disable local interrupts
* and need no spinlock.
*/
-
local_irq_save(flags);
cpu = smp_processor_id();
- queue = &softscsi_data[cpu];
-
- if (!queue->head) {
- queue->head = SCpnt;
- queue->tail = SCpnt;
- } else {
- queue->tail->bh_next = SCpnt;
- queue->tail = SCpnt;
- }
-
+ pdone_q = &done_q[cpu];
+ list_add_tail(&cmd->eh_entry, pdone_q);
cpu_raise_softirq(cpu, SCSI_SOFTIRQ);
local_irq_restore(flags);
}
/**
- * scsi_softirq - Perform post-interrupt handling for completed commands
+ * scsi_softirq - Perform post-interrupt processing of finished SCSI commands.
+ *
+ * This is the consumer of the done queue.
*
* This is called with all interrupts enabled. This should reduce
* interrupt latency, stack depth, and reentrancy of the low-level
*/
static void scsi_softirq(struct softirq_action *h)
{
- int cpu = smp_processor_id();
- struct softscsi_data *queue = &softscsi_data[cpu];
+ LIST_HEAD(local_q);
- while (queue->head) {
- Scsi_Cmnd *SCpnt, *SCnext;
+ local_irq_disable();
+ list_splice_init(&done_q[smp_processor_id()], &local_q);
+ local_irq_enable();
- local_irq_disable();
- SCpnt = queue->head;
- queue->head = NULL;
- local_irq_enable();
+ while (!list_empty(&local_q)) {
+ struct scsi_cmnd *cmd = list_entry(local_q.next,
+ struct scsi_cmnd, eh_entry);
+ list_del_init(&cmd->eh_entry);
- for (; SCpnt; SCpnt = SCnext) {
- SCnext = SCpnt->bh_next;
+ switch (scsi_decide_disposition(cmd)) {
+ case SUCCESS:
+ /*
+ * Add to BH queue.
+ */
+ SCSI_LOG_MLCOMPLETE(3,
+ printk("Command finished %d %d "
+ "0x%x\n",
+ cmd->device->host->host_busy,
+ cmd->device->host->host_failed,
+ cmd->result));
+
+ scsi_finish_command(cmd);
+ break;
+ case NEEDS_RETRY:
+ /*
+ * We only come in here if we want to retry a
+ * command. The test to see whether the
+ * command should be retried should be keeping
+ * track of the number of tries, so we don't
+ * end up looping, of course.
+ */
+ SCSI_LOG_MLCOMPLETE(3, printk("Command needs retry "
+ "%d %d 0x%x\n",
+ cmd->device->host->host_busy,
+ cmd->device->host->host_failed,
+ cmd->result));
- switch (scsi_decide_disposition(SCpnt)) {
- case SUCCESS:
- /*
- * Add to BH queue.
- */
- SCSI_LOG_MLCOMPLETE(3, printk("Command finished %d %d 0x%x\n", SCpnt->device->host->host_busy,
- SCpnt->device->host->host_failed,
- SCpnt->result));
+ scsi_retry_command(cmd);
+ break;
+ case ADD_TO_MLQUEUE:
+ /*
+ * This typically happens for a QUEUE_FULL
+ * message - typically only when the queue
+ * depth is only approximate for a given
+ * device. Adding a command to the queue for
+ * the device will prevent further commands
+ * from being sent to the device, so we
+ * shouldn't end up with tons of things being
+ * sent down that shouldn't be.
+ */
+ SCSI_LOG_MLCOMPLETE(3, printk("Command rejected as "
+ "device queue full, "
+ "put on ml queue %p\n",
+ cmd));
+ scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
+ break;
+ default:
+ /*
+ * Here we have a fatal error of some sort.
+ * Turn it over to the error handler.
+ */
+ SCSI_LOG_MLCOMPLETE(3,
+ printk("Command failed %p %x "
+ "busy=%d failed=%d\n",
+ cmd, cmd->result,
+ cmd->device->host->host_busy,
+ cmd->device->host->host_failed));
- scsi_finish_command(SCpnt);
- break;
- case NEEDS_RETRY:
- /*
- * We only come in here if we want to retry a
- * command. The test to see whether the
- * command should be retried should be keeping
- * track of the number of tries, so we don't
- * end up looping, of course.
- */
- SCSI_LOG_MLCOMPLETE(3, printk("Command needs retry %d %d 0x%x\n", SCpnt->device->host->host_busy,
- SCpnt->device->host->host_failed, SCpnt->result));
-
- scsi_retry_command(SCpnt);
- break;
- case ADD_TO_MLQUEUE:
- /*
- * This typically happens for a QUEUE_FULL
- * message - typically only when the queue
- * depth is only approximate for a given
- * device. Adding a command to the queue for
- * the device will prevent further commands
- * from being sent to the device, so we
- * shouldn't end up with tons of things being
- * sent down that shouldn't be.
- */
- SCSI_LOG_MLCOMPLETE(3, printk("Command rejected as device queue full, put on ml queue %p\n",
- SCpnt));
- scsi_queue_insert(SCpnt, SCSI_MLQUEUE_DEVICE_BUSY);
- break;
- default:
- /*
- * Here we have a fatal error of some sort.
- * Turn it over to the error handler.
- */
- SCSI_LOG_MLCOMPLETE(3,
- printk("Command failed %p %x busy=%d failed=%d\n",
- SCpnt, SCpnt->result,
- SCpnt->device->host->host_busy,
- SCpnt->device->host->host_failed));
+ /*
+ * Dump the sense information too.
+ */
+ if ((status_byte(cmd->result)&CHECK_CONDITION) != 0) {
+ SCSI_LOG_MLCOMPLETE(3, print_sense("bh", cmd));
+ }
+ if (!scsi_eh_scmd_add(cmd, 0)) {
/*
- * Dump the sense information too.
+ * We only get here if the error
+ * recovery thread has died.
*/
- if ((status_byte(SCpnt->result) & CHECK_CONDITION) != 0) {
- SCSI_LOG_MLCOMPLETE(3, print_sense("bh", SCpnt));
- }
-
- if (!scsi_eh_scmd_add(SCpnt, 0))
- {
- /*
- * We only get here if the error
- * recovery thread has died.
- */
- scsi_finish_command(SCpnt);
- }
- } /* switch */
- } /* for(; SCpnt...) */
- } /* while(queue->head) */
+ scsi_finish_command(cmd);
+ }
+ }
+ }
}
/*
static int __init init_scsi(void)
{
- int error;
+ int error, i;
error = scsi_init_queue();
if (error)
if (error)
goto cleanup_devlist;
+ for (i = 0; i < NR_CPUS; i++)
+ INIT_LIST_HEAD(&done_q[i]);
+
scsi_host_init();
devfs_mk_dir(NULL, "scsi", NULL);
open_softirq(SCSI_SOFTIRQ, scsi_softirq, NULL);
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