Re: ath9k: panic on tip/master

Re: ath9k: panic on tip/master

[Luis R. Rodriguez]

On Fri, Oct 03, 2008 at 11:09:31AM -0700, John W. Linville wrote:
> On Fri, Oct 03, 2008 at 11:35:23AM -0400, John W. Linville wrote:
> > On Fri, Oct 03, 2008 at 12:02:11PM +0200, Ingo Molnar wrote:
> > >
> > > * Steven Noonan <steven@uplinklabs.net> wrote:
> > >
> > > > Hey folks,
> > > >
> > > > Just got a panic on tip. According to the stack trace, ath9k is what
> > > > decided to bomb.
> > > >
> > > > http://www.uplinklabs.net/~tycho/linux/ath9k_panic_tip_10.3.2008.jpg
> > > >
> > > > Note: Although it says 'sudo modprobe radeon' on the bash prompt above
> > > > the panic, I never got to hit 'enter' on that command before the panic
> > > > occurred.
> > >
> > > it appears to me that ath9k's eth_rx_input() takes a spinlock that is
> > > not initialized (or already destroyed by the allocator).
> >
> > Seems reasonable...
> >
> > > this would be consistent with an IRQ storm hitting some race in the
> > > ath9k driver init sequence. For example if request_irq() is done before
> > > all structures that the IRQ handler relies on are properly initialized.
> > >
> > > i.e. this has the signature of a genuine ath9k bug.
> >
> > Agreed, although I don't see anything specifically relating to
> > request_irq or the like.
> >
> > I think the spin_lock call may actually be in ath_ampdu_input (called
> > from ath_rx_input), which perhaps is getting called simultaneous
> > with ath_rx_node_init still running?  With no locks in between them,
> > it seems like this could be the culprit?
> >
> > Sorry to not be more immediately helpful, but I'm going to have to
> > run in a few minutes.  Perhaps this insight is helpful for someone
> > more familiar with the internals of this driver?
> 
> This is probably a dead-end...I don't think the ath_node_find
> in ath__rx_indicate will be able to find the ath_node used
> in ath_ampdu_input unless ath_rx_node_init had already complete.
> Back to square one...

Well Steven, please give this a shot, we think this is the culprit.

[PATCH] ath9k: fix oops on trying to hold the wrong spinlock

We were trying to hold the wrong spinlock due to a typo
on IEEE80211_BAR_CTL_TID_S's definition. We use this to
compute the tid number and then hold this this tid number's
spinlock during ath_bar_rx().

Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
---
 drivers/net/wireless/ath9k/core.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/net/wireless/ath9k/core.h b/drivers/net/wireless/ath9k/core.h
index 2f84093..88f4cc3 100644
--- a/drivers/net/wireless/ath9k/core.h
+++ b/drivers/net/wireless/ath9k/core.h
@@ -316,7 +316,7 @@ void ath_descdma_cleanup(struct ath_softc *sc,
 #define ATH_RX_TIMEOUT           40      /* 40 milliseconds */
 #define WME_NUM_TID              16
 #define IEEE80211_BAR_CTL_TID_M  0xF000  /* tid mask */
-#define IEEE80211_BAR_CTL_TID_S  2       /* tid shift */
+#define IEEE80211_BAR_CTL_TID_S  12      /* tid shift */
 
 enum ATH_RX_TYPE {
 	ATH_RX_NON_CONSUMED = 0,
-- 
1.5.6.3

Re: ath9k: panic on tip/master

[John W. Linville]

On Fri, Oct 03, 2008 at 12:02:11PM +0200, Ingo Molnar wrote:
> 
> * Steven Noonan <steven@uplinklabs.net> wrote:
> 
> > Hey folks,
> > 
> > Just got a panic on tip. According to the stack trace, ath9k is what 
> > decided to bomb.
> > 
> > http://www.uplinklabs.net/~tycho/linux/ath9k_panic_tip_10.3.2008.jpg
> > 
> > Note: Although it says 'sudo modprobe radeon' on the bash prompt above 
> > the panic, I never got to hit 'enter' on that command before the panic 
> > occurred.
> 
> it appears to me that ath9k's eth_rx_input() takes a spinlock that is 
> not initialized (or already destroyed by the allocator).
 
Seems reasonable...

> this would be consistent with an IRQ storm hitting some race in the 
> ath9k driver init sequence. For example if request_irq() is done before 
> all structures that the IRQ handler relies on are properly initialized.
> 
> i.e. this has the signature of a genuine ath9k bug.

Agreed, although I don't see anything specifically relating to
request_irq or the like.

I think the spin_lock call may actually be in ath_ampdu_input (called
from ath_rx_input), which perhaps is getting called simultaneous
with ath_rx_node_init still running?  With no locks in between them,
it seems like this could be the culprit?

Sorry to not be more immediately helpful, but I'm going to have to
run in a few minutes.  Perhaps this insight is helpful for someone
more familiar with the internals of this driver?

John
-- 
John W. Linville		Linux should be at the core
linville@tuxdriver.com			of your literate lifestyle.

Re: ath9k: panic on tip/master

[John W. Linville]

On Fri, Oct 03, 2008 at 11:35:23AM -0400, John W. Linville wrote:
> On Fri, Oct 03, 2008 at 12:02:11PM +0200, Ingo Molnar wrote:
> > 
> > * Steven Noonan <steven@uplinklabs.net> wrote:
> > 
> > > Hey folks,
> > > 
> > > Just got a panic on tip. According to the stack trace, ath9k is what 
> > > decided to bomb.
> > > 
> > > http://www.uplinklabs.net/~tycho/linux/ath9k_panic_tip_10.3.2008.jpg
> > > 
> > > Note: Although it says 'sudo modprobe radeon' on the bash prompt above 
> > > the panic, I never got to hit 'enter' on that command before the panic 
> > > occurred.
> > 
> > it appears to me that ath9k's eth_rx_input() takes a spinlock that is 
> > not initialized (or already destroyed by the allocator).
>  
> Seems reasonable...
> 
> > this would be consistent with an IRQ storm hitting some race in the 
> > ath9k driver init sequence. For example if request_irq() is done before 
> > all structures that the IRQ handler relies on are properly initialized.
> > 
> > i.e. this has the signature of a genuine ath9k bug.
> 
> Agreed, although I don't see anything specifically relating to
> request_irq or the like.
> 
> I think the spin_lock call may actually be in ath_ampdu_input (called
> from ath_rx_input), which perhaps is getting called simultaneous
> with ath_rx_node_init still running?  With no locks in between them,
> it seems like this could be the culprit?
> 
> Sorry to not be more immediately helpful, but I'm going to have to
> run in a few minutes.  Perhaps this insight is helpful for someone
> more familiar with the internals of this driver?

This is probably a dead-end...I don't think the ath_node_find
in ath__rx_indicate will be able to find the ath_node used
in ath_ampdu_input unless ath_rx_node_init had already complete.
Back to square one...

John
-- 
John W. Linville		Linux should be at the core
linville@tuxdriver.com			of your literate lifestyle.