We disable local IRQs here in case of running complete() by
tasklet to avoid possible deadlock because drivers may call
spin_lock() to hold lock which might be acquired in one hard
interrupt handler.
The local_irq_save()/local_irq_restore() around complete()
will be removed if current USB drivers have been cleaned up
and no one may trigger the above deadlock situation when
running complete() in tasklet.
Cc: Oliver Neukum <oliver@xxxxxxxxxx>
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
---
drivers/usb/core/hcd.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index a272968..09a8263 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1673,7 +1673,28 @@ static void __usb_hcd_giveback_urb(struct urb *urb)
/* pass ownership to the completion handler */
urb->status = status;
- urb->complete (urb);
+
+ /*
+ * We disable local IRQs here in case of running complete() by
+ * tasklet to avoid possible deadlock because drivers may call
+ * spin_lock() to hold lock which might be acquired in one hard
+ * interrupt handler.
+ *
+ * The local_irq_save()/local_irq_restore() around complete()
+ * will be removed if current USB drivers have been cleaned up
+ * and no one may trigger the above deadlock situation when
+ * running complete() in tasklet.
+ */
+ if (hcd_giveback_urb_in_bh(hcd)) {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ urb->complete (urb);
+ local_irq_restore(flags);
+ } else {
+ urb->complete (urb);
+ }
+
atomic_dec (&urb->use_count);
if (unlikely(atomic_read(&urb->reject)))
wake_up (&usb_kill_urb_queue);
--
1.7.9.5
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