[4.2.y-ckt stable] Patch "r8152: fix lockup when runtime PM is enabled" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    r8152: fix lockup when runtime PM is enabled

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt1.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 69cef81e4ce348190db19c2bf902749828e8a6d4 Mon Sep 17 00:00:00 2001
From: Peter Wu <peter at lekensteyn.nl>
Date: Tue, 8 Dec 2015 12:17:42 +0100
Subject: r8152: fix lockup when runtime PM is enabled

[ Upstream commit 90186af404ada5a47b875bf3c16d0b02bb023ea0 ]

When an interface is brought up which was previously suspended (via
runtime PM), it would hang. This happens because napi_disable is called
before napi_enable.

Solve this by avoiding napi_enable in the resume during open function
(netif_running is true when open is called, IFF_UP is set after a
successful open; netif_running is false when close is called, but IFF_UP
is then still set).

While at it, remove WORK_ENABLE check from rtl8152_open (introduced with
the original change) because it cannot happen:

 - After this patch, runtime resume will not set it during rtl8152_open.
 - When link is up, rtl8152_open is not called.
 - When link is down during system/auto suspend/resume, it is not set.

Fixes: 41cec84cf285 ("r8152: don't enable napi before rx ready")
Link: https://lkml.kernel.org/r/20151205105912.GA1766@al
Signed-off-by: Peter Wu <peter at lekensteyn.nl>
Acked-by: Hayes Wang <hayeswang at realtek.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/net/usb/r8152.c | 21 +++------------------
 1 file changed, 3 insertions(+), 18 deletions(-)

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index ad8cbc6..d3d30e6 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -3025,17 +3025,6 @@ static int rtl8152_open(struct net_device *netdev)

 	mutex_lock(&tp->control);

-	/* The WORK_ENABLE may be set when autoresume occurs */
-	if (test_bit(WORK_ENABLE, &tp->flags)) {
-		clear_bit(WORK_ENABLE, &tp->flags);
-		usb_kill_urb(tp->intr_urb);
-		cancel_delayed_work_sync(&tp->schedule);
-
-		/* disable the tx/rx, if the workqueue has enabled them. */
-		if (netif_carrier_ok(netdev))
-			tp->rtl_ops.disable(tp);
-	}
-
 	tp->rtl_ops.up(tp);

 	rtl8152_set_speed(tp, AUTONEG_ENABLE,
@@ -3082,12 +3071,6 @@ static int rtl8152_close(struct net_device *netdev)
 	} else {
 		mutex_lock(&tp->control);

-		/* The autosuspend may have been enabled and wouldn't
-		 * be disable when autoresume occurs, because the
-		 * netif_running() would be false.
-		 */
-		rtl_runtime_suspend_enable(tp, false);
-
 		tp->rtl_ops.down(tp);

 		mutex_unlock(&tp->control);
@@ -3442,7 +3425,7 @@ static int rtl8152_resume(struct usb_interface *intf)
 		netif_device_attach(tp->netdev);
 	}

-	if (netif_running(tp->netdev)) {
+	if (netif_running(tp->netdev) && tp->netdev->flags & IFF_UP) {
 		if (test_bit(SELECTIVE_SUSPEND, &tp->flags)) {
 			rtl_runtime_suspend_enable(tp, false);
 			clear_bit(SELECTIVE_SUSPEND, &tp->flags);
@@ -3462,6 +3445,8 @@ static int rtl8152_resume(struct usb_interface *intf)
 		}
 		usb_submit_urb(tp->intr_urb, GFP_KERNEL);
 	} else if (test_bit(SELECTIVE_SUSPEND, &tp->flags)) {
+		if (tp->netdev->flags & IFF_UP)
+			rtl_runtime_suspend_enable(tp, false);
 		clear_bit(SELECTIVE_SUSPEND, &tp->flags);
 	}

--
1.9.1