netdev - [PATCH 2.6.29] can: fix slowpath issue in hrtimer callback function

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Message-ID: <496D97DC.9020408@hartkopp.net>
Date:	Wed, 14 Jan 2009 08:44:28 +0100
From:	Oliver Hartkopp <oliver@...tkopp.net>
To:	David Miller <davem@...emloft.net>
CC:	Linux Netdev List <netdev@...r.kernel.org>
Subject: [PATCH 2.6.29] can: fix slowpath issue in hrtimer callback function

Due to the loopback functionality in can_send() we can not invoke it 
from hardirq context which was done inside the bcm_tx_timeout_handler() 
hrtimer callback:


[  700.361154]  [<c012228c>] warn_slowpath+0x80/0xb6
[  700.361163]  [<c013d559>] valid_state+0x125/0x136
[  700.361171]  [<c013d858>] mark_lock+0x18e/0x332
[  700.361180]  [<c013e300>] __lock_acquire+0x12e/0xb1e
[  700.361189]  [<f8ab5915>] bcm_tx_timeout_handler+0x0/0xbc [can_bcm]
[  700.361198]  [<c031e20a>] dev_queue_xmit+0x191/0x479
[  700.361206]  [<c01262a7>] __local_bh_disable+0x2b/0x64
[  700.361213]  [<c031e20a>] dev_queue_xmit+0x191/0x479
[  700.361225]  [<f8aa69a1>] can_send+0xd7/0x11a [can]
[  700.361235]  [<f8ab522b>] bcm_can_tx+0x9d/0xd9 [can_bcm]
[  700.361245]  [<f8ab597f>] bcm_tx_timeout_handler+0x6a/0xbc [can_bcm]
[  700.361255]  [<f8ab5915>] bcm_tx_timeout_handler+0x0/0xbc [can_bcm]
[  700.361263]  [<c0134143>] __run_hrtimer+0x5a/0x86
[  700.361273]  [<f8ab5915>] bcm_tx_timeout_handler+0x0/0xbc [can_bcm]
[  700.361282]  [<c0134a50>] hrtimer_interrupt+0xb9/0x110


This patch moves the rest of the functionality from the hrtimer callback 
to the already existing tasklet to fix this slowpath problem.

Signed-off-by: Oliver Hartkopp <oliver@...tkopp.net>
---

Hello Dave,

this patch 'completes' the changes for the hrtimer update of the can-bcm 
in 2.6.29 :-]

Thanks,
Oliver


View attachment "bcm_tx_slowpath.patch" of type "text/x-patch" (2272 bytes)