Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:2 as permitted sender) client-ip=2620:137:e000::3:2;
Subject: Re: [PATCH] usb: musb: Get the musb_qh poniter after musb_giveback
To:     Xingxing Luo <xingxing.luo@unisoc.com>, <b-liu@ti.com>,
        <gregkh@linuxfoundation.org>
CC:     <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <xingxing0070.luo@gmail.com>, <Zhiyong.Liu@unisoc.com>,
        <Cixi.Geng1@unisoc.com>, <Orson.Zhai@unisoc.com>,
        <zhang.lyra@gmail.com>
References: <20230914015656.20856-1-xingxing.luo@unisoc.com>
From:   Sergey Shtylyov <s.shtylyov@omp.ru>
Organization: Open Mobile Platform
Message-ID: <8365ba2a-8ecd-d055-e962-3a7f2bfdbfb0@omp.ru>
Date:   Thu, 14 Sep 2023 13:06:14 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.10.1
MIME-Version: 1.0
In-Reply-To: <20230914015656.20856-1-xingxing.luo@unisoc.com>
Content-Type: text/plain; charset="utf-8"
Content-Language: en-US
Content-Transfer-Encoding: 7bit
X-KSE-Attachment-Filter-Triggered-Filters: Clean
X-KSE-BulkMessagesFiltering-Scan-Result: InTheLimit
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (agentk.vger.email [0.0.0.0]); Thu, 14 Sep 2023 03:06:38 -0700 (PDT)
X-Spam-Status: No, score=-2.2 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS
	autolearn=unavailable autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on agentk.vger.email

Hello!

On 9/14/23 4:56 AM, Xingxing Luo wrote:

> When multiple threads are performing USB transmission, musb->lock will be
> unlocked when musb_giveback is executed. At this time, qh may be released
> in the dequeue process in other threads, resulting in a wild pointer, so
> it needs to be here get qh again, and judge whether qh is NULL, and when
> dequeue, you need to set qh to NULL.
> 
> Fixes: dbac5d07d13e ("usb: musb: host: don't start next rx urb if current one failed")
> Signed-off-by: Xingxing Luo <xingxing.luo@unisoc.com>
> ---
>  drivers/usb/musb/musb_host.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
> index a02c29216955..9df27db5847a 100644
> --- a/drivers/usb/musb/musb_host.c
> +++ b/drivers/usb/musb/musb_host.c
> @@ -321,10 +321,16 @@ static void musb_advance_schedule(struct musb *musb, struct urb *urb,
>  	musb_giveback(musb, urb, status);
>  	qh->is_ready = ready;
>  
> +	/*
> +	 * musb->lock had been unlocked in musb_giveback, so somtimes qh

   Sometimes?

> +	 * may freed, need get it again
> +	 */
> +	qh = musb_ep_get_qh(hw_ep, is_in);
> +
>  	/* reclaim resources (and bandwidth) ASAP; deschedule it, and
>  	 * invalidate qh as soon as list_empty(&hep->urb_list)
>  	 */
> -	if (list_empty(&qh->hep->urb_list)) {
> +	if (qh != NULL && list_empty(&qh->hep->urb_list)) {

   Just qh, perhaps?

[...]

MBR, Sergey