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

From: Peter Wu
Date: Tue Dec 08 2015 - 09:33:43 EST

On Tue, Dec 08, 2015 at 12:39:12PM +0000, Hayes Wang wrote:
> Peter Wu [mailto:peter@xxxxxxxxxxxxx]
> > Sent: Tuesday, December 08, 2015 7:18 PM
> >
> > 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:
> > Signed-off-by: Peter Wu <peter@xxxxxxxxxxxxx>
> > ---
> > v2: moved rtl_runtime_suspend_enable from close to rtl8152_suspend
> Acked-by: Hayes Wang <hayeswang@xxxxxxxxxxx>
> Best Regards,
> Hayes

I found another problem with runtime PM. When a device is suspended via
autosuspend and a system suspend takes place, there is no network I/O
after resume. Triggering a renegotiation (ethtool -r eth1) brings back
network activity.

Can you have a look? I guess that reset_resume needs different
treatment, but don't know how to do it properly as suspend is not called
before system reset (because the device is apparently already in
suspended state).

I think that this new issue can be addressed in a different patch, this
patch solves a more severe lockup. Opinions?
Kind regards,
Peter Wu
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