From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA7D8C4363A for ; Wed, 21 Oct 2020 20:01:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5592A24178 for ; Wed, 21 Oct 2020 20:01:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2439259AbgJUUBp (ORCPT ); Wed, 21 Oct 2020 16:01:45 -0400 Received: from static.214.254.202.116.clients.your-server.de ([116.202.254.214]:34376 "EHLO ciao.gmane.io" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2410567AbgJUUBp (ORCPT ); Wed, 21 Oct 2020 16:01:45 -0400 Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1kVKIo-00056v-6m for linux-usb@vger.kernel.org; Wed, 21 Oct 2020 22:01:42 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: linux-usb@vger.kernel.org From: Ferry Toth Subject: Re: BUG with linux 5.9.0 with dwc3 in gadget mode Date: Wed, 21 Oct 2020 22:01:32 +0200 Message-ID: References: <913dccca-500d-1938-b199-6eb67cfb60cc@gmail.com> <87a6wig461.fsf@kernel.org> <874kmpf583.fsf@kernel.org> <976cea12-e54e-fbca-6c53-e6ef5c554094@synopsys.com> <645b6ddc-d4f5-3f5b-b85f-b3d27fc365f5@synopsys.com> <20201021014725.GA26640@jackp-linux.qualcomm.com> <3fee07f4-7950-c281-670b-bbc8f0426a8e@synopsys.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 Cc: Ferry Toth , "linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "felipe.balbi-VuQAYsv1563Yd54FQh9/CA-XMD5yJDbdMReXY1tMh2IBg@public.gmane.org" , Heikki Krogerus , Andy Shevchenko In-Reply-To: <3fee07f4-7950-c281-670b-bbc8f0426a8e@synopsys.com> Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Op 21-10-2020 om 03:56 schreef Thinh Nguyen: > Jack Pham wrote: >> Hi Thinh, Ferry, >> >> On Tue, Oct 20, 2020 at 10:58:31PM +0000, Thinh Nguyen wrote: >>> Thinh Nguyen wrote: >>>> Hi, >>>> >>>> Ferry Toth wrote: >>>>> Op 20-10-2020 om 14:32 schreef Felipe Balbi: >>>>>> Hi, >>>>>> >>>>>> Ferry Toth writes: >>>>>> >>>>>> 8< snip >>>>>> >>>>>>>>> [   12.657416] CR2: 0000000100000000 >>>>>>>>> [   12.660729] ---[ end trace 9b92dea6da33c71e ]--- >>>>>>>> It this something you can reproduce on your end? Ferry, can you get >>>>>>>> dwc3 >>>>>>>> trace logs when this happens? ftrace_dump_on_oops may help here. >>>>>>> I will do that tonight. Is flipping on ftrace_dump_on_oops >>>>>>> sufficient or >>>>>>> do I need to do more? >>>>>> you'd have to enable dwc3 trace events first ;-) >>>>>> >>>>>>> BTW after posting this I found in host mode dwc3 is not working >>>>>>> properly >>>>>>> either. No oops, but no driver get loaded on device plug in. >>>>>> okay >>>>>> >>>>> Ehem, you maybe only me to enable /dwc3/dwc3_ep_dequeue/enable: >>>>> >>>>> root@edison:/boot# uname -a >>>>> Linux edison 5.9.0-edison-acpi-standard #1 SMP Mon Oct 19 20:17:04 UTC >>>>> 2020 x86_64 x86_64 x86_64 GNU/Linux >>>>> root@edison:/boot# echo 1 > >>>>> /sys/kernel/debug/tracing/events/dwc3/dwc3_ep_dequeue/enable >>>>> root@edison:/boot# echo 1 > /proc/sys/kernel/ftrace_dump_on_oops >>>>> root@edison:/boot# >>>>> root@edison:/boot# [ 2608.585323] BUG: kernel NULL pointer >>>>> dereference, address: 0000000000000000 >>>>> [ 2608.592288] #PF: supervisor read access in kernel mode >>>>> [ 2608.597419] #PF: error_code(0x0000) - not-present page >>>>> [ 2608.602549] PGD 0 P4D 0 >>>>> [ 2608.605090] Oops: 0000 [#1] SMP PTI >>>>> [ 2608.608580] CPU: 1 PID: 733 Comm: irq/15-dwc3 Not tainted >>>>> 5.9.0-edison-acpi-standard #1 >>>>> [ 2608.616571] Hardware name: Intel Corporation Merrifield/BODEGA BAY, >>>>> BIOS 542 2015.01.21:18.19.48 >>>>> [ 2608.625356] RIP: 0010:dwc3_gadget_ep_dequeue+0x41/0x1c0 >>>>> [ 2608.630580] Code: e9 51 01 00 00 4c 8d a3 30 01 00 00 4c 89 e7 e8 >>>>> 15 e6 42 00 49 8b 4e 48 49 89 c5 49 8d 46 48 48 8d 51 a0 48 39 c8 75 >>>>> 0f eb 2e <48> 8b 4a 60 48 8d 51 a0 48 39 c8 74 21 48 39 d5 75 ee 45 31 >>>>> f6 4c >>>>> [ 2608.649320] RSP: 0018:ffffa838002a7c40 EFLAGS: 00010087 >>>>> [ 2608.654543] RAX: ffff9a5f4609c048 RBX: ffff9a5f46f48028 RCX: >>>>> 0000000000000000 >>>>> [ 2608.661666] RDX: ffffffffffffffa0 RSI: 0000000000000008 RDI: >>>>> ffff9a5f46f48158 >>>>> [ 2608.668790] RBP: ffff9a5f7bd09b40 R08: 00000000000002d8 R09: >>>>> ffff9a5f7dd6a000 >>>>> [ 2608.675913] R10: ffffa838002a7d90 R11: ffff9a5f46f48300 R12: >>>>> ffff9a5f46f48158 >>>>> [ 2608.683039] R13: 0000000000000046 R14: ffff9a5f4609c000 R15: >>>>> ffff9a5f7ad77e00 >>>>> [ 2608.690165] FS:  0000000000000000(0000) GS:ffff9a5f7e300000(0000) >>>>> knlGS:0000000000000000 >>>>> [ 2608.698244] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>>> [ 2608.703980] CR2: 0000000000000000 CR3: 000000003780a000 CR4: >>>>> 00000000001006e0 >>>>> [ 2608.711102] Call Trace: >>>>> [ 2608.713561]  usb_ep_dequeue+0x19/0x80 >>>>> [ 2608.717234]  u_audio_stop_capture+0x54/0x9a [u_audio] >>>>> [ 2608.722289]  afunc_set_alt+0x73/0x80 [usb_f_uac2] >>>> I took a look at how the audio function is handling switching alternate >>>> setting and dequeuing endpoints, and I think I found the issue. >>>> >>>> Here's a snippet of the free_ep() code in u_audio.c: >>>> >>>> static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep) >>>> { >>>>     ..... >>>>         for (i = 0; i < params->req_number; i++) { >>>>                 if (prm->ureq[i].req) { >>>>                         usb_ep_dequeue(ep, prm->ureq[i].req); >>>>                         usb_ep_free_request(ep, prm->ureq[i].req); >>>>                         prm->ureq[i].req = NULL; >>>>                 } >>>>         } >>>>   .... >>>> >>>> >>>> usb_ep_dequeue() can be asynchronous. The dwc3 still has ownership of >>>> the request until it gives back the request. Freeing the request >>>> immediately here will cause a problem. >>> To confirm my suspicion, can you try this and see if you still get oops? >>> >>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c >>> index eec8e9a9e3ed..b66eb24ec070 100644 >>> --- a/drivers/usb/dwc3/gadget.c >>> +++ b/drivers/usb/dwc3/gadget.c >>> @@ -2031,6 +2031,7 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep, >>>                         list_for_each_entry_safe(r, t, >>> &dep->started_list, list) >>>                                 dwc3_gadget_move_cancelled_request(r); >>> >>> +                       dwc3_gadget_ep_cleanup_cancelled_requests(dep); >>>                         goto out; >>>                 } >>>         } >>> >>> >>> This will make usb_ep_dequeue() synchronous. (Note that this is not tested). >> But only for dwc3 right? In general do other UDC drivers provide >> synchronous behavior? It does states clearly in the kerneldoc for >> usb_ep_dequeue() that the completion is asynchronous. From >> drivers/usb/gadget/udc/core.c: >> >> * If the request is still active on the endpoint, it is dequeued and >> * eventually its completion routine is called (with status -ECONNRESET); >> * else a negative error code is returned. This routine is asynchronous, >> * that is, it may return before the completion routine runs. >> >> Alternatively, could we not fix up u_audio.c to deal with this? > > The issue is in u_audio.c. But I want to confirm my suspicion about > whether the oops that Ferry is due to this (most likely it is). When I disable uac2 from my config this oops goes away. But I also have have eem (ethernet), which appears and then drops away. So, seems there are more things wrong. > We don't want to apply this as a workaround and mask the issue in audio.c. > >> >> diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c >> index 56906d15fb55..f08f036d520e 100644 >> --- a/drivers/usb/gadget/function/u_audio.c >> +++ b/drivers/usb/gadget/function/u_audio.c >> @@ -89,7 +89,12 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req) >> struct snd_uac_chip *uac = prm->uac; >> >> /* i/f shutting down */ >> - if (!prm->ep_enabled || req->status == -ESHUTDOWN) >> + if (!prm->ep_enabled) { >> + usb_ep_free_request(ep, req); >> + return; >> + } >> + >> + if (req->status == -ESHUTDOWN) >> return; >> >> /* >> @@ -352,7 +357,6 @@ static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep) >> for (i = 0; i < params->req_number; i++) { >> if (prm->ureq[i].req) { >> usb_ep_dequeue(ep, prm->ureq[i].req); >> - usb_ep_free_request(ep, prm->ureq[i].req); >> prm->ureq[i].req = NULL; >> } >> } >> >> Jack > > Yes, the u_audio.c needs to do something like that. > > BR, > Thinh >