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From: Alan Stern <stern@rowland.harvard.edu>
To: Peter Chen <peter.chen@nxp.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"balbi@kernel.org" <balbi@kernel.org>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	dl-linux-imx <linux-imx@nxp.com>
Subject: Re: [PATCH 1/1] usb: gadget: core: wait gadget device .release finishing at usb_del_gadget_udc
Date: Fri, 31 Jul 2020 10:12:48 -0400
Message-ID: <20200731141248.GC36650@rowland.harvard.edu> (raw)
In-Reply-To: <20200731140553.GA8013@b29397-desktop>

On Fri, Jul 31, 2020 at 02:06:20PM +0000, Peter Chen wrote:
> On 20-07-31 14:25:20, Greg Kroah-Hartman wrote:
> > On Fri, Jul 31, 2020 at 12:11:32PM +0000, Peter Chen wrote:
> > 
> > Grab a reference from somewhere else and do not give it up for a long
> > time.
> > 
> 
> So wait_for_completion_timeout is suitable? The similar use case is when
> we open the file at the USB Drive at Windows, and we click "Eject", it
> will say "The device is currently in use", and refuse our "Eject"
> operation.
> 
> When we try to remove the gadget, if the gadget is in use, we could
> refuse the remove operation, reasonable?

No, the real solution is to fix the UDC drivers.  They need to allocate 
the gadget structure dynamically instead of reusing it.  And they should 
have a real release routine that deallocates the gadget structure.

Alan Stern

  reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-31  9:59 Peter Chen
2020-07-31 11:55 ` Greg Kroah-Hartman
2020-07-31 12:11   ` Peter Chen
2020-07-31 12:25     ` Greg Kroah-Hartman
2020-07-31 14:06       ` Peter Chen
2020-07-31 14:12         ` Alan Stern [this message]
2020-07-31 23:42           ` Peter Chen
2020-08-01  6:53             ` Peter Chen
2020-08-01  7:04               ` Jun Li
2020-08-01 15:44               ` Alan Stern
2020-07-31 14:16         ` Greg Kroah-Hartman

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