[PATCH v2] r8152: fix lockup when runtime PM is enabled

Peter Wu
2015-12-08T11:18:00Z

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@lekensteyn.nl>
---
v2: moved rtl_runtime_suspend_enable from close to rtl8152_suspend

Tested with the scenario from
https://lkml.kernel.org/r/20151208111008.GA18728@al
(added debug prints to verify the suspend/resume moments)
---
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 d9427ca..2e32c41 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -3067,17 +3067,6 @@ 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,
@@ -3124,12 +3113,6 @@ 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);
@@ -3512,7 +3495,7 @@ 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);
@@ -3532,6 +3515,8 @@ 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);
}

--
2.6.3