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From: Jeaho Hwang <jhhwang@rtst.co.kr>
To: peter.chen@kernel.org, linux-usb@vger.kernel.org
Cc: "Linux team" <team-linux@rtst.co.kr>,
	"변무광(Byeon Moo Kwang)/자동화연)Automation Platform연구팀"
	<mkbyeon@lselectric.co.kr>
Subject: Chipidea USB device goes infinite loop due to interrupt while hw_ep_prime
Date: Mon, 2 Aug 2021 17:38:07 +0900	[thread overview]
Message-ID: <CAJk_X9i5+Yzb97NT+iEtxMKGqG-tWs3065LOqJ9HMN6Gea_eqA@mail.gmail.com> (raw)

Hi.

We found an infinite loop inside the function hw_ep_set_halt
(drivers/usb/chipidea/udc.c) if a cablle is repeatedly
connnected/disconnected while ping through RNDIS with chipidea USB
device.

Using ftrace tracing, we found that hw_ep_set_halt is called due to
error return of hw_ep_prime(drivers/usb/chipidea/udc.c:202) which is
called from isr_tr_complete_handler -> isr_setup_status_phase ->
_ep_queue.

The comment of function hw_ep_prime says (execute without
interruption) but timer interrupt is occurred while hw_ep_prime is
executing. We believe that the interrupt causes an error return of
hw_ep_prime. We tried to protect hw_ep_prime from irqs and then no
case of the infinite loop is occurred.

I want ask if it is appropriate way that turning off irq inside
(threaded) irq handlers. And should we explicitly turn off irqs before
calling hw_ep_prime?

Thanks.

-- 
황재호, Jay Hwang, linux team manager of RTst
010-7242-1593

             reply	other threads:[~2021-08-02  8:38 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-02  8:38 Jeaho Hwang [this message]
     [not found] <CAJk_X9hBB_edByfEvueSyWgKjpYGZbS2rPLPCSpRrPr+icFz_Q@mail.gmail.com>
2021-08-04  1:32 ` Chipidea USB device goes infinite loop due to interrupt while hw_ep_prime Peter Chen
2021-08-04  2:03   ` Jeaho Hwang
2021-08-09  1:27     ` Peter Chen
2021-08-09  1:45       ` Jeaho Hwang
2021-08-09  6:31         ` Peter Chen
2021-08-04  3:11   ` Jeaho Hwang
2021-08-09  1:40     ` Peter Chen

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