From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Minas Harutyunyan <hminas@synopsys.com>,
Felipe Balbi <felipe.balbi@linux.intel.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: Re: [PATCH] usb: dwc2: Revert "usb: dwc2: Disable all EP's on disconnect"
Date: Thu, 6 Dec 2018 16:07:14 +0100 [thread overview]
Message-ID: <5abb1e89-bf49-6c08-742a-a782111b41dc@samsung.com> (raw)
In-Reply-To: <20181206145218.GQ3073@unbuntlaptop>
Hi Dan,
On 2018-12-06 15:52, Dan Carpenter wrote:
> Hi Marek,
>
> I'm surprised you don't get deadlocks when you apply this patch.
Why should I get it? It is just a revert to the state before applying
the mentioned incorrect patch.
> On Wed, Nov 21, 2018 at 04:45:04PM +0100, Marek Szyprowski wrote:
>
>> @@ -4020,9 +4008,7 @@ static int dwc2_hsotg_ep_disable(struct usb_ep *ep)
>>
>> epctrl_reg = dir_in ? DIEPCTL(index) : DOEPCTL(index);
>>
>> - locked = spin_is_locked(&hsotg->lock);
>> - if (!locked)
>> - spin_lock_irqsave(&hsotg->lock, flags);
>> + spin_lock_irqsave(&hsotg->lock, flags);
>>
> One of the callers is already holding the hsotg->log. The
> spin_is_locked() test would avoid the deadlock.
Before that broken patch, there was no call to any function which takes
spinlock again, so no deadlock.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
prev parent reply other threads:[~2018-12-06 15:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20181121154518eucas1p2cc7ffd4d071ff420c747e1d0c387ee5d@eucas1p2.samsung.com>
2018-11-21 15:45 ` [PATCH] usb: dwc2: Revert "usb: dwc2: Disable all EP's on disconnect" Marek Szyprowski
2018-11-22 6:53 ` Minas Harutyunyan
2018-11-23 9:49 ` Marek Szyprowski
2018-11-23 14:43 ` Dan Carpenter
2018-12-04 12:34 ` Minas Harutyunyan
2018-12-04 13:29 ` Dan Carpenter
2018-12-05 12:52 ` Minas Harutyunyan
2018-12-07 10:15 ` Dan Carpenter
2018-12-07 11:20 ` Minas Harutyunyan
2018-12-07 14:13 ` Minas Harutyunyan
2018-12-07 14:40 ` Dan Carpenter
2018-12-06 15:03 ` Marek Szyprowski
2018-12-07 9:06 ` Minas Harutyunyan
2018-12-07 9:50 ` Felipe Balbi
2018-12-07 9:58 ` Minas Harutyunyan
2018-12-07 10:11 ` Felipe Balbi
2018-12-06 23:09 ` Maynard CABIENTE
2018-12-07 9:06 ` Minas Harutyunyan
2018-12-06 14:52 ` Dan Carpenter
2018-12-06 15:07 ` Marek Szyprowski [this message]
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