Am Samstag, 6. März 2010 16:34:31 schrieb Alan Stern:
> On Sat, 6 Mar 2010, Oliver Neukum wrote:
>
> > From e58722a5fc0c00bceaea1f70d5024f6325ac3a6c Mon Sep 17 00:00:00 2001
> > From: Oliver Neukum <oliver@xxxxxxxxxx>
> > Date: Sat, 6 Mar 2010 12:09:41 +0100
> > Subject: [PATCH] usb: usbfs: Fix deadlock of khubd
> >
> > The caller of usbfs_conn_disc_event() already holds usbfs_mutex.
> > Don't take it again.
>
> That's not true. The caller holds usbfs_mutex only when the action is
> USB_DEVICE_REMOVE. Not when the action is USB_DEVICE_ADD or USB_BUS_*.
That is, there's no obvious solution but it is inelegant.
Regards
Oliver
>From d0da57c398ccc23a5b50ce7353b32983f9270eb5 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oliver@xxxxxxxxxx>
Date: Sat, 6 Mar 2010 17:16:51 +0100
Subject: [PATCH] usb: usbfs: Fix deadlock of khubd
The caller of usbfs_conn_disc_event() already holds usbfs_mutex.
Don't take it again.
Signed-off-by: Oliver Neukum <neukum@xxxxxxxxxxxxx>
---
drivers/usb/core/devices.c | 3 +--
drivers/usb/core/inode.c | 4 ++++
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/core/devices.c b/drivers/usb/core/devices.c
index c83c975..08def6b 100644
--- a/drivers/usb/core/devices.c
+++ b/drivers/usb/core/devices.c
@@ -155,11 +155,10 @@ static const struct class_info clas_info[] =
/*****************************************************************/
+/* the caller holds usbfs_mutex */
void usbfs_conn_disc_event(void)
{
- mutex_lock(&usbfs_mutex);
conndiscevcnt++;
- mutex_unlock(&usbfs_mutex);
wake_up(&deviceconndiscwq);
}
diff --git a/drivers/usb/core/inode.c b/drivers/usb/core/inode.c
index 97b40ce..2d332af 100644
--- a/drivers/usb/core/inode.c
+++ b/drivers/usb/core/inode.c
@@ -740,7 +740,11 @@ static int usbfs_notify(struct notifier_block *self, unsigned long action, void
}
usbfs_update_special();
+ if (action != USB_DEVICE_REMOVE)
+ mutex_lock(&usbfs_mutex);
usbfs_conn_disc_event();
+ if (action != USB_DEVICE_REMOVE)
+ mutex_unlock(&usbfs_mutex);
return NOTIFY_OK;
}
--
1.6.4.2
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