linux-kernel - Re: [Fwd: [PlanetCCRMA] atl1 driver; sleeping function]

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Date:	Tue, 31 Jul 2007 10:51:22 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Fernando Lopez-Lezcano <nando@...ma.Stanford.EDU>
Cc:	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
	Matt Barber <brbrofsvl@...il.com>
Subject: Re: [Fwd: [PlanetCCRMA] atl1 driver; sleeping function]


* Fernando Lopez-Lezcano <nando@...ma.Stanford.EDU> wrote:

> Hi Ingo, I'm forwading this report from a Planet CCRMA user, this is 
> happening to him with 2.6.21.6-rt21...

thanks!

> BUG: sleeping function called from invalid context IRQ-219(2243) at
> kernel/rtmutex.c:613
> in_atomic():0 [00000000], irqs_disabled():1
>  [<c0405f88>] dump_trace+0x64/0x105
>  [<c0406041>] show_trace_log_lvl+0x18/0x2c
>  [<c040664e>] show_trace+0xf/0x11
>  [<c04066cf>] dump_stack+0x12/0x14
>  [<c060511d>] __rt_spin_lock+0x21/0x3d
>  [<f8a20e0c>] atl1_xmit_frame+0x66f/0x6c6 [atl1]
>  [<c05a3d96>] dev_hard_start_xmit+0x1c6/0x225
>  [<c05b29bd>] __qdisc_run+0xb7/0x1cf

could you try the patch below, does it fix the problem? The atl1 driver 
uses raw irq flags in combination with a spinlock that is a sleeping 
lock on -rt. (this is valid code on upstream, fortunately the -rt fix is 
also a cleanup and a small code reduction enhancement on upstream, so 
there's no problem pushing such fixes upstream.)

	Ingo

--------------------------->
Subject: [patch] drivers/net/atl1/atl1_main.c: use spin_trylock_irqsave()
From: Ingo Molnar <mingo@...e.hu>

use the simpler spin_trylock_irqsave() API to get the adapter lock.

[ this is also a fix for -rt where adapter->lock is a sleeping lock. ]

Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 drivers/net/atl1/atl1_main.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

Index: linux-rt-rebase.q/drivers/net/atl1/atl1_main.c
===================================================================
--- linux-rt-rebase.q.orig/drivers/net/atl1/atl1_main.c
+++ linux-rt-rebase.q/drivers/net/atl1/atl1_main.c
@@ -1704,10 +1704,8 @@ static int atl1_xmit_frame(struct sk_buf
 		}
 	}
 
-	local_irq_save(flags);
-	if (!spin_trylock(&adapter->lock)) {
+	if (!spin_trylock_irqsave(&adapter->lock, flags)) {
 		/* Can't get lock - tell upper layer to requeue */
-		local_irq_restore(flags);
 		dev_printk(KERN_DEBUG, &adapter->pdev->dev, "tx locked\n");
 		return NETDEV_TX_LOCKED;
 	}
-
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