From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Greg KH <greg@kroah.com>, Peter Ujfalusi <peter.ujfalusi@ti.com>,
vkoul@kernel.org, dan.j.williams@intel.com,
dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
tony@atomide.com, linux-omap@vger.kernel.org,
Felipe Balbi <felipe.balbi@linux.intel.com>
Subject: Re: [PATCH] dmaengine: ti: omap-dma: Configure LCH_TYPE for OMAP1
Date: Sat, 24 Nov 2018 19:29:28 +0000 [thread overview]
Message-ID: <20181124192928.GR6920@n2100.armlinux.org.uk> (raw)
In-Reply-To: <20181124190648.GB3416@darkstar.musicnaut.iki.fi>
On Sat, Nov 24, 2018 at 09:06:48PM +0200, Aaro Koskinen wrote:
> Hello,
>
> On Sat, Nov 24, 2018 at 05:48:23PM +0000, Russell King - ARM Linux wrote:
> > Hmm, there's more questionable stuff in this driver, and the gadget
> > layer.
>
> [...]
>
> > So, whatever way I look at this, the code in the removal path both
> > in omap_udc and the gadget removal code higher up looks very wrong
> > and broken to me.
>
> Yes, week ago I saw omap_udc crashing on both probe failure and
> module removal and sent some fixes for the most obvious failures (see
> https://marc.info/?l=linux-usb&m=154258778316932&w=2).
The effect of your patch is basically to replace the release function
with a no-op function.
> Is there any good driver that uses usb_add_gadget_udc_release() correctly?
> Looking at fsl_qe_udc.c and fsl_udc_core.c they should also crash if
> usb_add_gadget_udc_release() fails.
usb_add_gadget_udc_release() itself will call the release function
automatically on error.
The release function should _also_ be called when usb_del_gadget_udc()
is called (and would be guaranteed if the memset() is removed.)
So, moving the cleanup in the remove path into the release function
would solve the problem with omap_udc, and removing the memset()
would solve the problem with the core code.
It does leave a problem if the omap_udc module is removed - the
release function _could_ be called after the module has been removed
which would lead to an oops. That's presumably why there's a
completion. One solution to that would be to move the assignment
of udc->done before the call to usb_del_gadget_udc().
However, using a completion for something like this tends to be
frowned upon, but I don't see any other way to ensure correctness
here.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2018-11-24 19:29 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-19 10:40 [PATCH] dmaengine: ti: omap-dma: Configure LCH_TYPE for OMAP1 Peter Ujfalusi
2018-11-19 18:46 ` Aaro Koskinen
2018-11-20 7:28 ` Peter Ujfalusi
2018-11-20 21:04 ` Aaro Koskinen
2018-11-22 8:31 ` Peter Ujfalusi
2018-11-22 22:01 ` Aaro Koskinen
2018-11-23 11:45 ` Peter Ujfalusi
2018-11-24 0:17 ` Aaro Koskinen
2018-11-24 17:48 ` Russell King - ARM Linux
2018-11-24 19:06 ` Aaro Koskinen
2018-11-24 19:29 ` Russell King - ARM Linux [this message]
2018-11-22 10:29 ` Russell King - ARM Linux
2018-11-22 15:12 ` Russell King - ARM Linux
2018-11-22 22:24 ` Aaro Koskinen
2018-11-23 0:25 ` Russell King - ARM Linux
2018-11-23 1:23 ` Aaro Koskinen
2018-11-23 11:54 ` Peter Ujfalusi
2018-11-23 12:35 ` Peter Ujfalusi
2018-11-23 15:43 ` Russell King - ARM Linux
2018-11-23 16:16 ` Russell King - ARM Linux
2018-11-23 23:27 ` Russell King - ARM Linux
2018-11-23 18:52 ` Aaro Koskinen
2018-11-24 20:09 ` Russell King - ARM Linux
2018-11-25 1:07 ` Tony Lindgren
2018-11-25 1:11 ` Tony Lindgren
2018-11-25 11:11 ` Russell King - ARM Linux
2018-11-25 11:57 ` Russell King - ARM Linux
2018-11-25 16:58 ` Aaro Koskinen
2018-11-25 17:14 ` Tony Lindgren
2018-12-17 23:47 ` Aaro Koskinen
2018-12-18 15:55 ` Tony Lindgren
2018-12-17 19:16 ` Aaro Koskinen
2018-12-18 10:11 ` Peter Ujfalusi
2018-11-23 11:49 ` Peter Ujfalusi
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