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[24.9.64.241]) by smtp.gmail.com with ESMTPSA id j6sm113586ooj.11.2021.08.18.11.36.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 Aug 2021 11:36:12 -0700 (PDT) Subject: Re: [PATCH v3 1/2] usbip: give back URBs for unsent unlink requests during cleanup To: Greg KH Cc: Anirudh Rayabharam , valentina.manea.m@gmail.com, shuah@kernel.org, syzbot+74d6ef051d3d2eacf428@syzkaller.appspotmail.com, linux-kernel-mentees@lists.linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Shuah Khan References: <20210813182508.28127-1-mail@anirudhrb.com> <20210813182508.28127-2-mail@anirudhrb.com> <13450a85-bbfe-09c5-d614-1a944c2600c2@linuxfoundation.org> From: Shuah Khan Message-ID: Date: Wed, 18 Aug 2021 12:36:11 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On 8/17/21 11:39 PM, Greg KH wrote: > On Tue, Aug 17, 2021 at 05:16:51PM -0600, Shuah Khan wrote: >> On 8/13/21 12:25 PM, Anirudh Rayabharam wrote: >>> In vhci_device_unlink_cleanup(), the URBs for unsent unlink requests are >>> not given back. This sometimes causes usb_kill_urb to wait indefinitely >>> for that urb to be given back. syzbot has reported a hung task issue [1] >>> for this. >>> >>> To fix this, give back the urbs corresponding to unsent unlink requests >>> (unlink_tx list) similar to how urbs corresponding to unanswered unlink >>> requests (unlink_rx list) are given back. >>> >>> [1]: https://syzkaller.appspot.com/bug?id=08f12df95ae7da69814e64eb5515d5a85ed06b76 >>> >>> Reported-by: syzbot+74d6ef051d3d2eacf428@syzkaller.appspotmail.com >>> Tested-by: syzbot+74d6ef051d3d2eacf428@syzkaller.appspotmail.com >>> Signed-off-by: Anirudh Rayabharam >>> --- >>> drivers/usb/usbip/vhci_hcd.c | 26 ++++++++++++++++++++++++++ >>> 1 file changed, 26 insertions(+) >>> >>> diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c >>> index 4ba6bcdaa8e9..6f3f374d4bbc 100644 >>> --- a/drivers/usb/usbip/vhci_hcd.c >>> +++ b/drivers/usb/usbip/vhci_hcd.c >>> @@ -957,8 +957,34 @@ static void vhci_device_unlink_cleanup(struct vhci_device *vdev) >>> spin_lock(&vdev->priv_lock); >>> list_for_each_entry_safe(unlink, tmp, &vdev->unlink_tx, list) { >>> + struct urb *urb; >>> + >>> + /* give back URB of unsent unlink request */ >>> pr_info("unlink cleanup tx %lu\n", unlink->unlink_seqnum); >> >> I know this is an exiting one. >> Let's make this pr_debug or remove it all together. >> >>> + >>> + urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum); >>> + if (!urb) { >>> + pr_info("the urb (seqnum %lu) was already given back\n", >>> + unlink->unlink_seqnum); >> >> Let's make this pr_debug or remove it all together. > > As you have a struct device for all of these, please use dev_dbg() and > friends, not pr_*(), for all of these. > Yes. Makes perfect sense. thanks, -- Shuah