Re: sleeping while atomic in dwc3_gadget_start

[Felipe Balbi]

Hi,

On Thu, Jun 27, 2013 at 09:57:52AM -0700, Stephen Boyd wrote:
> On 06/26/13 23:58, Felipe Balbi wrote:
> > On Wed, Jun 26, 2013 at 02:52:56PM -0700, Stephen Boyd wrote:
> >> Hi,
> >>
> >> I'm getting the folllowing BUG message on bootup with 3.10-rc5
> >>
> >> BUG: sleeping function called from invalid context at mm/slub.c:926
> >> in_atomic(): 1, irqs_disabled(): 128, pid: 1, name: swapper/0
> >> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.10.0-rc5-gee3e35b-09316-ge78f3b35 #643
> >> [<c0014220>] (unwind_backtrace+0x0/0x120) from [<c001212c>] (show_stack+0x10/0x14)
> >> [<c001212c>] (show_stack+0x10/0x14) from [<c0143750>] (kmem_cache_alloc_trace+0x3c/0x210)
> >> [<c0143750>] (kmem_cache_alloc_trace+0x3c/0x210) from [<c00e0c60>] (request_threaded_irq+0x88/0x11c)
> >> [<c00e0c60>] (request_threaded_irq+0x88/0x11c) from [<c03bf53c>] (dwc3_gadget_start+0x198/0x200)
> >> [<c03bf53c>] (dwc3_gadget_start+0x198/0x200) from [<c03f7a5c>] (udc_bind_to_driver+0x70/0xd8)
> >> [<c03f7a5c>] (udc_bind_to_driver+0x70/0xd8) from [<c03f7b50>] (usb_gadget_probe_driver+0x8c/0xb8)
> >>
> >> and I suspect this problem was introduced in commit 8698e2acf
> >> (usb: dwc3: gadget: introduce and use enable/disable irq
> >> methods). Is there a fix for this problem? Can we just move the
> >> irq request outside the spinlock?
> > nice :-)
> >
> > how about this ?
> 
> If start fails do you call stop? I believe the answer is no, so we'll
> need to free_irq() somewhere along the error path. Or we can request it
> after the spin_unlock()?

good point here's v2:

From 1a7896c5481646e533ca09ba60918831d9849ed8 Mon Sep 17 00:00:00 2001
From: Felipe Balbi <balbi@xxxxxx>
Date: Thu, 27 Jun 2013 10:00:18 +0300
Subject: [PATCH] usb: dwc3: gadget: don't request IRQs in atomic

We cannot request an IRQ with spinlocks held
as that would trigger a sleeping inside
spinlock warning.

Cc: <stable@xxxxxxxxxxxxxxx> # v3.10
Reported-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Signed-off-by: Felipe Balbi <balbi@xxxxxx>
---
 drivers/usb/dwc3/gadget.c | 37 ++++++++++++++++++++-----------------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index b5e5b35..bb0d312c 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1508,6 +1508,15 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 	int			irq;
 	u32			reg;
 
+	irq = platform_get_irq(to_platform_device(dwc->dev), 0);
+	ret = request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt,
+			IRQF_SHARED | IRQF_ONESHOT, "dwc3", dwc);
+	if (ret) {
+		dev_err(dwc->dev, "failed to request irq #%d --> %d\n",
+				irq, ret);
+		goto err0;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 
 	if (dwc->gadget_driver) {
@@ -1515,7 +1524,7 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 				dwc->gadget.name,
 				dwc->gadget_driver->driver.name);
 		ret = -EBUSY;
-		goto err0;
+		goto err1;
 	}
 
 	dwc->gadget_driver	= driver;
@@ -1551,41 +1560,35 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 	ret = __dwc3_gadget_ep_enable(dep, &dwc3_gadget_ep0_desc, NULL, false);
 	if (ret) {
 		dev_err(dwc->dev, "failed to enable %s\n", dep->name);
-		goto err0;
+		goto err1;
 	}
 
 	dep = dwc->eps[1];
 	ret = __dwc3_gadget_ep_enable(dep, &dwc3_gadget_ep0_desc, NULL, false);
 	if (ret) {
 		dev_err(dwc->dev, "failed to enable %s\n", dep->name);
-		goto err1;
+		goto err2;
 	}
 
 	/* begin to receive SETUP packets */
 	dwc->ep0state = EP0_SETUP_PHASE;
 	dwc3_ep0_out_start(dwc);
 
-	irq = platform_get_irq(to_platform_device(dwc->dev), 0);
-	ret = request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt,
-			IRQF_SHARED | IRQF_ONESHOT, "dwc3", dwc);
-	if (ret) {
-		dev_err(dwc->dev, "failed to request irq #%d --> %d\n",
-				irq, ret);
-		goto err1;
-	}
-
 	dwc3_gadget_enable_irq(dwc);
 
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	return 0;
 
-err1:
+err2:
 	__dwc3_gadget_ep_disable(dwc->eps[0]);
 
-err0:
+err1:
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
+err0:
+	free_irq(irq, dwc);
+
 	return ret;
 }
 
@@ -1599,9 +1602,6 @@ static int dwc3_gadget_stop(struct usb_gadget *g,
 	spin_lock_irqsave(&dwc->lock, flags);
 
 	dwc3_gadget_disable_irq(dwc);
-	irq = platform_get_irq(to_platform_device(dwc->dev), 0);
-	free_irq(irq, dwc);
-
 	__dwc3_gadget_ep_disable(dwc->eps[0]);
 	__dwc3_gadget_ep_disable(dwc->eps[1]);
 
@@ -1609,6 +1609,9 @@ static int dwc3_gadget_stop(struct usb_gadget *g,
 
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
+	irq = platform_get_irq(to_platform_device(dwc->dev), 0);
+	free_irq(irq, dwc);
+
 	return 0;
 }
 
-- 
1.8.2.1


-- 
balbi

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