[patch 35/60] esp_scsi: fix reset cleanup spinlock recursion

Greg KH
2007-12-13T07:10:40Z

[-- Attachment #1: esp_scsi-fix-reset-cleanup-spinlock-recursion.patch --]
[-- Type: text/plain, Size: 4189 bytes --]

2.6.23-stable review patch. If anyone has any objections, please let us
know.

------------------
From: "Maciej W. Rozycki" <macro@linux-mips.org>

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>

---
drivers/scsi/esp_scsi.c | 4 ++--
drivers/scsi/scsi.c | 31 +++++++++++++++++++++++++++++--
include/scsi/scsi_device.h | 3 +++
3 files changed, 34 insertions(+), 4 deletions(-)

--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -2026,8 +2026,8 @@ static void esp_reset_cleanup(struct 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;
}
--- 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
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
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -222,6 +222,9 @@ extern struct scsi_device *__scsi_device
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 *,

--