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Message-ID: <46E81D405FFAC240826E54028B3B02953B22@aixlac.qosmotec.com>
Date: Wed, 4 Oct 2006 22:58:48 +0200
From: "Axel C. Voigt" <Axel.Voigt@...motec.com>
To: "Jarek Poplawski" <jarkao2@...pl>, "Greg KH" <gregkh@...e.de>
Cc: <linux-kernel@...r.kernel.org>, "David Kubicek" <dave@....cz>
Subject: RE: Problems with hard irq? (inconsistent lock state)
Hello,
problem seems solved, testing extensively does not show the described behavior any more. What exactly does the patch using _irqsave functions instead of their counterparts? Is this worth to make public patch or just a quick hack to solve this particular problem?
Mit freundlichen Grüssen/ with kind regards,
Axel C. Voigt
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-----Original Message-----
From: Jarek Poplawski [mailto:jarkao2@...pl]
Sent: Wednesday, October 04, 2006 8:46 AM
To: Greg KH
Cc: Axel C. Voigt; linux-kernel@...r.kernel.org; David Kubicek
Subject: Re: Problems with hard irq? (inconsistent lock state)
On Tue, Oct 03, 2006 at 10:43:09PM -0700, Greg KH wrote:
> On Wed, Oct 04, 2006 at 07:43:08AM +0200, Jarek Poplawski wrote:
> > On 29-09-2006 13:45, Axel C. Voigt wrote:
...
> > > Sep 29 13:29:53 mcs70 kernel: =================================
> > > Sep 29 13:29:53 mcs70 kernel: [ INFO: inconsistent lock state ]
> > > Sep 29 13:29:53 mcs70 kernel: ---------------------------------
> > > Sep 29 13:29:53 mcs70 kernel: inconsistent {hardirq-on-W} -> {in-hardirq-W} usage.
> > > Sep 29 13:29:53 mcs70 kernel: startDV24/3864 [HC1[1]:SC0[0]:HE0:SE1] takes:
> > > Sep 29 13:29:53 mcs70 kernel: (&acm->read_lock){++..}, at:
> > > [<e08952d8>] acm_read_bulk+0x60/0xde [cdc_acm] Sep 29 13:29:53 mcs70 kernel: {hardirq-on-W} state was registered at:
...
> > It looks in drivers/usb/class/cdc-acm.c acm_rx_tasklet could be
> > preempted with acm->read_lock by acm_read_bulk which uses the same
> > lock from hardirq context.
> >
> > So probably spin_lock_irqsave is needed.
>
> Yup. Care to send a patch?
If it could help?
Jarek P.
diff -Nurp linux-2.6-18-git20-/drivers/usb/class/cdc-acm.c linux-2.6-18-git20/drivers/usb/class/cdc-acm.c
--- linux-2.6-18-git20-/drivers/usb/class/cdc-acm.c 2006-10-04 07:59:46.000000000 +0200
+++ linux-2.6-18-git20/drivers/usb/class/cdc-acm.c 2006-10-04 08:16:03.000000000 +0200
@@ -325,7 +325,7 @@ static void acm_rx_tasklet(unsigned long
struct acm_rb *buf;
struct tty_struct *tty = acm->tty;
struct acm_ru *rcv;
- //unsigned long flags;
+ unsigned long flags;
int i = 0;
dbg("Entering acm_rx_tasklet");
@@ -333,15 +333,15 @@ static void acm_rx_tasklet(unsigned long
return;
next_buffer:
- spin_lock(&acm->read_lock);
+ spin_lock_irqsave(&acm->read_lock, flags);
if (list_empty(&acm->filled_read_bufs)) {
- spin_unlock(&acm->read_lock);
+ spin_unlock_irqrestore(&acm->read_lock, flags);
goto urbs;
}
buf = list_entry(acm->filled_read_bufs.next,
struct acm_rb, list);
list_del(&buf->list);
- spin_unlock(&acm->read_lock);
+ spin_unlock_irqrestore(&acm->read_lock, flags);
dbg("acm_rx_tasklet: procesing buf 0x%p, size = %d", buf, buf->size);
@@ -356,29 +356,29 @@ next_buffer:
memmove(buf->base, buf->base + i, buf->size - i);
buf->size -= i;
spin_unlock(&acm->throttle_lock);
- spin_lock(&acm->read_lock);
+ spin_lock_irqsave(&acm->read_lock, flags);
list_add(&buf->list, &acm->filled_read_bufs);
- spin_unlock(&acm->read_lock);
+ spin_unlock_irqrestore(&acm->read_lock, flags);
return;
}
spin_unlock(&acm->throttle_lock);
- spin_lock(&acm->read_lock);
+ spin_lock_irqsave(&acm->read_lock, flags);
list_add(&buf->list, &acm->spare_read_bufs);
- spin_unlock(&acm->read_lock);
+ spin_unlock_irqrestore(&acm->read_lock, flags);
goto next_buffer;
urbs:
while (!list_empty(&acm->spare_read_bufs)) {
- spin_lock(&acm->read_lock);
+ spin_lock_irqsave(&acm->read_lock, flags);
if (list_empty(&acm->spare_read_urbs)) {
- spin_unlock(&acm->read_lock);
+ spin_unlock_irqrestore(&acm->read_lock, flags);
return;
}
rcv = list_entry(acm->spare_read_urbs.next,
struct acm_ru, list);
list_del(&rcv->list);
- spin_unlock(&acm->read_lock);
+ spin_unlock_irqrestore(&acm->read_lock, flags);
buf = list_entry(acm->spare_read_bufs.next,
struct acm_rb, list);
@@ -400,9 +400,9 @@ urbs:
free-urbs-pool and resubmited ASAP */
if (usb_submit_urb(rcv->urb, GFP_ATOMIC) < 0) {
list_add(&buf->list, &acm->spare_read_bufs);
- spin_lock(&acm->read_lock);
+ spin_lock_irqsave(&acm->read_lock, flags);
list_add(&rcv->list, &acm->spare_read_urbs);
- spin_unlock(&acm->read_lock);
+ spin_unlock_irqrestore(&acm->read_lock, flags);
return;
}
}
-
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