Re: [PATCH v2 3/7] usb: mtu3: fix kernel panic at qmu transfer done irq handler

["Chunfeng Yun (云春峰)" <Chunfeng.Yun@mediatek.com>]

On Fri, 2023-04-07 at 11:09 +0200, AngeloGioacchino Del Regno wrote:
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> 
> Il 07/04/23 10:29, Chunfeng Yun ha scritto:
> > When handle qmu transfer irq, it will unlock @mtu->lock before give
> > back
> > request, if another thread handle disconnect event at the same
> > time, and
> > try to disable ep, it may lock @mtu->lock and free qmu ring, then
> > qmu
> > irq hanlder may get a NULL gpd, avoid the KE by checking gpd's
> > value before
> > handling it.
> > 
> > e.g.
> > qmu done irq on cpu0                 thread running on cpu1
> > 
> > qmu_done_tx()
> >    handle gpd [0]
> >      mtu3_requ_complete()        mtu3_gadget_ep_disable()
> >        unlock @mtu->lock
> >          give back request         lock @mtu->lock
> >                                      mtu3_ep_disable()
> >                                        mtu3_gpd_ring_free()
> >                                     unlock @mtu->lock
> >        lock @mtu->lock
> >      get next gpd [1]
> > 
> > [1]: goto [0] to handle next gpd, and next gpd may be NULL.
> > 
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> 
> NACK. You still miss the Fixes tag.
Ok, I'll add it, thanks

> 
> Regards,
> Angelo
>