esp_scsi: fix reset cleanup spinlock recursion

patch 522939d45c293388e6a360210905f9230298df16 in mainline.

The esp_reset_cleanup() function is called with the host lock held and
invokes starget_for_each_device() which wants to take it too.  Here is a
fix along the lines of shost_for_each_device()/__shost_for_each_device()
adding a __starget_for_each_device() counterpart which assumes the lock
has already been taken.

Eventually, I think the driver should get modified so that more work is
done as a softirq rather than in the interrupt context, but for now it
fixes a bug that causes the spinlock debugger to fire.

While at it, it fixes a small number of cosmetic problems with
starget_for_each_device() too.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 34 insertions, 4 deletions

diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index 95cf7b6cd62..f2c91bcb470 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -2026,8 +2026,8 @@ static void esp_reset_cleanup(struct esp *esp)
 		tp->flags |= ESP_TGT_CHECK_NEGO;
 
 		if (tp->starget)
-			starget_for_each_device(tp->starget, NULL,
-						esp_clear_hold);
+			__starget_for_each_device(tp->starget, NULL,
+						  esp_clear_hold);
 	}
 	esp->flags &= ~ESP_FLAG_RESETTING;
 }
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index a5de1a829a7..537c4e441e0 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -886,11 +886,11 @@ EXPORT_SYMBOL(__scsi_iterate_devices);
  * starget_for_each_device  -  helper to walk all devices of a target
  * @starget:	target whose devices we want to iterate over.
  *
- * This traverses over each devices of @shost.  The devices have
+ * This traverses over each device of @starget.  The devices have
  * a reference that must be released by scsi_host_put when breaking
  * out of the loop.
  */
-void starget_for_each_device(struct scsi_target *starget, void * data,
+void starget_for_each_device(struct scsi_target *starget, void *data,
 		     void (*fn)(struct scsi_device *, void *))
 {
 	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
@@ -905,6 +905,33 @@ void starget_for_each_device(struct scsi_target *starget, void * data,
 EXPORT_SYMBOL(starget_for_each_device);
 
 /**
+ * __starget_for_each_device  -  helper to walk all devices of a target
+ *				 (UNLOCKED)
+ * @starget:	target whose devices we want to iterate over.
+ *
+ * This traverses over each device of @starget.  It does _not_
+ * take a reference on the scsi_device, so the whole loop must be
+ * protected by shost->host_lock.
+ *
+ * Note:  The only reason why drivers would want to use this is because
+ * they need to access the device list in irq context.  Otherwise you
+ * really want to use starget_for_each_device instead.
+ **/
+void __starget_for_each_device(struct scsi_target *starget, void *data,
+			       void (*fn)(struct scsi_device *, void *))
+{
+	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+	struct scsi_device *sdev;
+
+	__shost_for_each_device(sdev, shost) {
+		if ((sdev->channel == starget->channel) &&
+		    (sdev->id == starget->id))
+			fn(sdev, data);
+	}
+}
+EXPORT_SYMBOL(__starget_for_each_device);
+
+/**
  * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
  * @starget:	SCSI target pointer
  * @lun:	SCSI Logical Unit Number
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index d5057bc338f..c1d659d42bd 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -222,6 +222,9 @@ extern struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *,
 							  uint);
 extern void starget_for_each_device(struct scsi_target *, void *,
 		     void (*fn)(struct scsi_device *, void *));
+extern void __starget_for_each_device(struct scsi_target *, void *,
+				      void (*fn)(struct scsi_device *,
+						 void *));
 
 /* only exposed to implement shost_for_each_device */
 extern struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *,