linux-kernel - Re: [PATCH 3/7] usb: mtu3: fix KE at qmu transfer done irq handler

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Message-ID: <1cfde490-40a4-c83b-3bd5-c9baeba5187d@collabora.com>
Date:   Mon, 3 Apr 2023 14:31:34 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-usb@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Eddie Hung <eddie.hung@...iatek.com>,
        Tianping Fang <tianping.fang@...iatek.com>
Subject: Re: [PATCH 3/7] usb: mtu3: fix KE at qmu transfer done irq handler

Il 03/04/23 04:52, Chunfeng Yun ha scritto:
> When handle qmu transfer irq, it will unlock @mtu->lock before give back
> request, if another thread hanlde 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

KE == Kernel Error? I think you wanted to say KP == Kernel Panic instead.

Also, s/hanlder/handler/g.

> 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@...iatek.com>

This is a fix and needs a Fixes tag.

Regards,
Angelo