On Tue, 13 Sep 2005, Christoph Hellwig wrote:
> I don't think we even need the waitque, a wake_up_process can replace
> it when there's only a single process waiting on it ever. Similarly
> we don't need eh_alive - EH must be alive after scsi_add_host returned,
> and no command may be in flight before that.
Okay, how do you like this patch instead? I haven't tested it yet.
Alan Stern
Index: usb-2.6/drivers/scsi/scsi_error.c
===================================================================
--- usb-2.6.orig/drivers/scsi/scsi_error.c
+++ usb-2.6/drivers/scsi/scsi_error.c
@@ -50,7 +50,7 @@
void scsi_eh_wakeup(struct Scsi_Host *shost)
{
if (shost->host_busy == shost->host_failed) {
- up(shost->eh_wait);
+ wake_up_process(shost->ehandler);
SCSI_LOG_ERROR_RECOVERY(5,
printk("Waking error handler thread\n"));
}
@@ -69,9 +69,6 @@ int scsi_eh_scmd_add(struct scsi_cmnd *s
struct Scsi_Host *shost = scmd->device->host;
unsigned long flags;
- if (shost->eh_wait == NULL)
- return 0;
-
spin_lock_irqsave(shost->host_lock, flags);
scmd->eh_eflags |= eh_flag;
@@ -1582,37 +1579,33 @@ int scsi_error_handler(void *data)
{
struct Scsi_Host *shost = (struct Scsi_Host *) data;
int rtn;
- DECLARE_MUTEX_LOCKED(sem);
current->flags |= PF_NOFREEZE;
- shost->eh_wait = &sem;
-
- /*
- * Wake up the thread that created us.
- */
- SCSI_LOG_ERROR_RECOVERY(3, printk("Wake up parent of"
- " scsi_eh_%d\n",shost->host_no));
while (1) {
- /*
- * If we get a signal, it means we are supposed to go
- * away and die. This typically happens if the user is
- * trying to unload a module.
- */
SCSI_LOG_ERROR_RECOVERY(1, printk("Error handler"
" scsi_eh_%d"
" sleeping\n",shost->host_no));
/*
- * Note - we always use down_interruptible with the semaphore
- * even if the module was loaded as part of the kernel. The
- * reason is that down() will cause this thread to be counted
- * in the load average as a running process, and down
- * interruptible doesn't. Given that we need to allow this
- * thread to die if the driver was loaded as a module, using
- * semaphores isn't unreasonable.
- */
- down_interruptible(&sem);
+ * Note - we always use TASK_INTERRUPTIBLE even if the
+ * module was loaded as part of the kernel. The reason
+ * is that UNINTERRUPTIBLE would cause this thread to be
+ * counted in the load average as a running process, and
+ * an interruptible wait doesn't.
+ */
+ for (;;) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (shost->host_busy == shost->host_failed ||
+ kthread_should_stop()) {
+ set_current_state(TASK_RUNNING);
+ break;
+ }
+
+ /* Even though we are INTERRUPTIBLE, ignore signals */
+ flush_signals(current);
+ schedule();
+ }
if (kthread_should_stop())
break;
@@ -1648,10 +1641,6 @@ int scsi_error_handler(void *data)
SCSI_LOG_ERROR_RECOVERY(1, printk("Error handler scsi_eh_%d"
" exiting\n",shost->host_no));
- /*
- * Make sure that nobody tries to wake us up again.
- */
- shost->eh_wait = NULL;
return 0;
}
Index: usb-2.6/include/scsi/scsi_host.h
===================================================================
--- usb-2.6.orig/include/scsi/scsi_host.h
+++ usb-2.6/include/scsi/scsi_host.h
@@ -465,8 +465,6 @@ struct Scsi_Host {
struct list_head eh_cmd_q;
struct task_struct * ehandler; /* Error recovery thread. */
- struct semaphore * eh_wait; /* The error recovery thread waits
- on this. */
struct semaphore * eh_action; /* Wait for specific actions on the
host. */
unsigned int eh_active:1; /* Indicates the eh thread is awake and active if
-
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