> -----Original Message----- > From: Ben Hutchings [mailto:b...@decadent.org.uk] > Sent: Monday, April 30, 2012 11:15 PM > To: Iyer, Shyam > Cc: Sven Hoexter; 670...@bugs.debian.org > Subject: Deadlock in hid_reset when Dell iDRAC is reset > > I'm handling a bug report to Debian by Sven Hoexter (cc'd) involving > lockups on Dell hardware, which seem to involve USB HID reset. The bug > report is at <http://bugs.debian.org/670398>.
It doesn't seem like this is the same bug.
Was the usb reset issue found while resetting the iDRAC ?
Resetting the iDRAC is an out of band process and has to be issued via a
separate management network to the iDRAC.
Besides this is not an upstream bug and hence was tailor made for RHEL6.
To me it still looks like this could be a symptomatic log of this bug
BZ#772884
On large SMP systems, the TSC (Time Stamp Counter) clock frequency could be
incorrectly calculated. The discrepancy between the correct value and the
incorrect value was within 0.5%. When the system rebooted, this small error
would result in the system becoming out of synchronization with an external
reference clock (typically a NTP server). With this update, the TSC frequency
calculation has been improved and the clock correctly maintains synchronization
with external reference clocks.
>
> I found that Red Hat recently made a bug fix credited to you, described
> as:
>
> BZ#797205
> Due to a bug in the hid_reset() function, a deadlock could
> occur
> when a Dell iDRAC controller was reset. Consequently, its USB
> keyboard or mouse device became unresponsive. A patch that
> fixes
> the underlying code has been provided to address this bug and
> the hangs no longer occur in the described scenario.
>
> Do the symptoms that Sven found match your understanding of the bug?
>
> Ben.
>
> (I was also able to extract a patch by comparing the Red Hat packages:
>
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -469,10 +469,8 @@
> * talking to TTs must queue control transfers (not just bulk and
> iso), so
> * both can talk to the same hub concurrently.
> */
> -static void hub_tt_work(struct work_struct *work)
> +void _hub_tt_work(struct usb_hub *hub)
> {
> - struct usb_hub *hub =
> - container_of(work, struct usb_hub, tt.clear_work);
> unsigned long flags;
> int limit = 100;
>
> @@ -507,6 +505,14 @@
> spin_unlock_irqrestore (&hub->tt.lock, flags); }
>
> +void hub_tt_work(struct work_struct *work) {
> + struct usb_hub *hub =
> + container_of(work, struct usb_hub, tt.clear_work);
> +
> + _hub_tt_work(hub);
> +}
> +
> /**
> * usb_hub_clear_tt_buffer - clear control/bulk TT state in high speed
> hub
> * @urb: an URB associated with the failed or incomplete split
> transaction @@ -554,7 +560,20 @@
> /* tell keventd to clear state for this TT */
> spin_lock_irqsave (&tt->lock, flags);
> list_add_tail (&clear->clear_list, &tt->clear_list);
> - schedule_work(&tt->clear_work);
> + /* don't schedule on kevent if we're running on keventd (e.g.,
> + * in hid_reset we can get here on kevent) unless on >=2.6.36
> + */
> + if (!(current->flags & PF_KTHREAD) || !strstr(current->comm,
> "events"))
> + /* put it on keventd */
> + schedule_work(&tt->clear_work);
> + else {
> + /* let khubd do it */
> + struct usb_hub *hub =
> + container_of(&tt->clear_work, struct usb_hub,
> + tt.clear_work);
> + kick_khubd(hub);
> + }
> +
> spin_unlock_irqrestore (&tt->lock, flags);
> return 0;
> }
> @@ -3421,6 +3440,10 @@
> if (hub->quiescing)
> goto loop_autopm;
>
> + /* _hub_tt_work usually run on keventd */
> + if (!list_empty(&hub->tt.clear_list))
> + _hub_tt_work(hub);
> +
> if (hub->error) {
> dev_dbg (hub_dev, "resetting for error %d\n",
> hub->error);
> -- END ---
>
> but if you can provide a version with your own description and sign-
> off, I would be grateful for it.)
Sure(see attached).
But like I said you might need instead the fix for the above bz I referenced.
Thanks,
Shyam
>
> --
> Ben Hutchings
> Design a system any fool can use, and only a fool will want to use it.
0001-usb-Fix-deadlock-in-hid_reset-when-Dell-iDRAC.patch
Description: 0001-usb-Fix-deadlock-in-hid_reset-when-Dell-iDRAC.patch
