[PATCH] sungem: fix suspend regression due to NAPI changes

Commit bea3348e (the NAPI changes) made sungem unconditionally enable
NAPI when resuming and unconditionally disable when suspending, this,
however, makes napi_disable() hang when suspending when the interface
was taken down before suspend because taking the interface down also
disables NAPI. This patch makes touching the napi struct in
suspend/resume code paths depend on having the interface up, thereby
fixing the hang on suspend.

The patch also moves the napi_disable() in gem_close() under the lock so
that the NAPI state is always modified atomically together with the
"opened" variable.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

---
 drivers/net/sungem.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

--- everything.orig/drivers/net/sungem.c	2007-11-12 18:22:49.948748047 +0100
+++ everything/drivers/net/sungem.c	2007-11-12 18:24:30.708748481 +0100

@@ -2333,10 +2333,10 @@ static int gem_close(struct net_device *
 {
 	struct gem *gp = dev->priv;
 
-	napi_disable(&gp->napi);
-
 	mutex_lock(&gp->pm_mutex);
 
+	napi_disable(&gp->napi);
+
 	gp->opened = 0;
 	if (!gp->asleep)
 		gem_do_stop(dev, 0);

@@ -2355,8 +2355,6 @@ static int gem_suspend(struct pci_dev *p
 
 	mutex_lock(&gp->pm_mutex);
 
-	napi_disable(&gp->napi);
-
 	printk(KERN_INFO "%s: suspending, WakeOnLan %s\n",
 	       dev->name,
 	       (gp->wake_on_lan && gp->opened) ? "enabled" : "disabled");

@@ -2370,6 +2368,8 @@ static int gem_suspend(struct pci_dev *p
 
 	/* If the driver is opened, we stop the MAC */
 	if (gp->opened) {
+		napi_disable(&gp->napi);
+
 		/* Stop traffic, mark us closed */
 		netif_device_detach(dev);
 

@@ -2460,6 +2460,7 @@ static int gem_resume(struct pci_dev *pd
 		/* Re-attach net device */
 		netif_device_attach(dev);
 
+		napi_enable(&gp->napi);
 	}
 
 	spin_lock_irqsave(&gp->lock, flags);

@@ -2479,8 +2480,6 @@ static int gem_resume(struct pci_dev *pd
 	spin_unlock(&gp->tx_lock);
 	spin_unlock_irqrestore(&gp->lock, flags);
 
-	napi_enable(&gp->napi);
-
 	mutex_unlock(&gp->pm_mutex);
 
 	return 0;

On Mon, 2007-11-12 at 18:45 +0100, Johannes Berg wrote:

Commit bea3348e (the NAPI changes) made sungem unconditionally enable
NAPI when resuming and unconditionally disable when suspending, this,
however, makes napi_disable() hang when suspending when the interface
was taken down before suspend because taking the interface down also
disables NAPI. This patch makes touching the napi struct in
suspend/resume code paths depend on having the interface up, thereby
fixing the hang on suspend.

The patch also moves the napi_disable() in gem_close() under the lock so
that the NAPI state is always modified atomically together with the
"opened" variable.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

Thanks for fixing that !

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 13 Nov 2007 09:32:46 +1100

On Mon, 2007-11-12 at 18:45 +0100, Johannes Berg wrote:

quoted

Commit bea3348e (the NAPI changes) made sungem unconditionally enable
NAPI when resuming and unconditionally disable when suspending, this,
however, makes napi_disable() hang when suspending when the interface
was taken down before suspend because taking the interface down also
disables NAPI. This patch makes touching the napi struct in
suspend/resume code paths depend on having the interface up, thereby
fixing the hang on suspend.

The patch also moves the napi_disable() in gem_close() under the lock so
that the NAPI state is always modified atomically together with the
"opened" variable.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

Thanks for fixing that !

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Indeed, thanks a lot Johannes.

Patch applied.