From: Felipe Balbi <balbi@ti.com>
To: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: "Shimoda, Yoshihiro" <yoshihiro.shimoda.uh@renesas.com>,
linux-kernel@vger.kernel.org, linux-sh@vger.kernel.org,
Vinod Koul <vinod.koul@intel.com>,
Magnus Damm <magnus.damm@gmail.com>,
linux-mmc@vger.kernel.org, alsa-devel@alsa-project.org,
linux-serial@vger.kernel.org, Paul Mundt <lethal@linux-sh.org>,
linux-usb@vger.kernel.org
Subject: Re: [PATCH/RFC] usb: fix renesas_usbhs to not schedule in atomic context
Date: Sun, 5 Feb 2012 16:54:00 +0200 [thread overview]
Message-ID: <20120205145358.GA13762@legolas.emea.dhcp.ti.com> (raw)
In-Reply-To: <Pine.LNX.4.64.1202031623000.6211@axis700.grange>
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Hi,
On Fri, Feb 03, 2012 at 04:43:20PM +0100, Guennadi Liakhovetski wrote:
> The current renesas_usbhs driver triggers
>
> BUG: scheduling while atomic: ksoftirqd/0/3/0x00000102
>
> with enabled CONFIG_DEBUG_ATOMIC_SLEEP, by submitting DMA transfers from
> an atomic (tasklet) context, which is not supported by the shdma dmaengine
> driver. Fix it by switching to a work. Also simplify some list
> manipulations.
you are doing much more than what you say. Also, instead of using a
workqueue, have you considered using threaded_irqs ?
(I didn't go over the driver again to see if it makes sense to use
threaded_irqs in this case, but doesn't hurt asking)
> Shimoda-san, this is the problem, that you were observing. However, it
> exists with the present version of shdma just as well as with the new one
> - on top of the simple DMA library. I marked it an RFC because (1) I only
> lightly tested it with the gadget device on mackerel with the mass storage
> gadget, and (2) I am somewhat concerned about races. Currently the work
> function runs with no locking and there are no usual cancel_work_sync()
> points in the patch. However, it has also been like this before with the
> tasklet implementation, which is not much better, and it looks like there
> are no asynchronous operations on the same packets like timeouts. Only
> asynchronous events, that I can think about are things like unloading the
> driver or unplugging the cable, but these have been there before too. It
> would become worse on SMP, I think. Comments welcome.
>
> diff --git a/drivers/usb/renesas_usbhs/fifo.c b/drivers/usb/renesas_usbhs/fifo.c
> index 72339bd..4d739ec 100644
> --- a/drivers/usb/renesas_usbhs/fifo.c
> +++ b/drivers/usb/renesas_usbhs/fifo.c
> @@ -75,8 +75,7 @@ void usbhs_pkt_push(struct usbhs_pipe *pipe, struct usbhs_pkt *pkt,
> pipe->handler = &usbhsf_null_handler;
> }
>
> - list_del_init(&pkt->node);
> - list_add_tail(&pkt->node, &pipe->list);
> + list_move_tail(&pkt->node, &pipe->list);
>
> /*
> * each pkt must hold own handler.
> @@ -106,7 +105,7 @@ static struct usbhs_pkt *__usbhsf_pkt_get(struct usbhs_pipe *pipe)
> if (list_empty(&pipe->list))
> return NULL;
>
> - return list_entry(pipe->list.next, struct usbhs_pkt, node);
> + return list_first_entry(&pipe->list, struct usbhs_pkt, node);
these two hunks are not part of $SUBJECT
--
balbi
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next prev parent reply other threads:[~2012-02-05 14:54 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-26 14:56 [PATCH 0/7 v2] extract a simple dmaengine library from shdma.c Guennadi Liakhovetski
2012-01-26 14:56 ` [PATCH 1/7 v2] dmaengine: add a simple dma library Guennadi Liakhovetski
2012-01-26 17:34 ` [alsa-devel] " Sascha Hauer
2012-01-26 21:07 ` Guennadi Liakhovetski
2012-01-27 8:37 ` Shimoda, Yoshihiro
2012-01-27 8:48 ` Guennadi Liakhovetski
2012-01-31 11:03 ` Shimoda, Yoshihiro
2012-02-01 0:52 ` Guennadi Liakhovetski
2012-02-01 2:47 ` Shimoda, Yoshihiro
2012-02-02 22:19 ` Guennadi Liakhovetski
2012-02-03 8:47 ` Shimoda, Yoshihiro
2012-02-03 10:21 ` Guennadi Liakhovetski
2012-02-03 15:43 ` [PATCH/RFC] usb: fix renesas_usbhs to not schedule in atomic context Guennadi Liakhovetski
2012-02-05 14:54 ` Felipe Balbi [this message]
2012-02-06 10:11 ` Guennadi Liakhovetski
2012-02-06 10:31 ` Felipe Balbi
2012-02-06 8:52 ` Shimoda, Yoshihiro
2012-01-30 8:32 ` [PATCH 1/7 v2] dmaengine: add a simple dma library Vinod Koul
2012-01-30 9:34 ` Guennadi Liakhovetski
2012-01-31 6:41 ` Vinod Koul
2012-01-31 8:59 ` Guennadi Liakhovetski
2012-02-01 5:38 ` Vinod Koul
2012-02-03 16:38 ` Guennadi Liakhovetski
2012-02-06 2:54 ` Vinod Koul
2012-02-06 9:53 ` Guennadi Liakhovetski
2012-01-26 14:56 ` [PATCH 2/7 v2] dma: shdma: prepare for simple DMA conversion Guennadi Liakhovetski
2012-01-26 14:56 ` [PATCH 3/7 v2] mmc: sh_mmcif: remove unneeded struct sh_mmcif_dma, prepare for simple DMA Guennadi Liakhovetski
2012-01-26 14:56 ` [PATCH 4/7 v2] mmc: sh_mobile_sdhi: prepare for conversion to " Guennadi Liakhovetski
2012-01-26 14:56 ` [PATCH 5/7 v2] serial: sh-sci: " Guennadi Liakhovetski
2012-01-26 14:56 ` [PATCH 6/7 v2] ASoC: SIU: " Guennadi Liakhovetski
2012-02-06 2:33 ` Vinod Koul
2012-02-06 9:11 ` Guennadi Liakhovetski
2012-01-26 14:56 ` [PATCH 7/7 v2] dma: shdma: convert to the simple DMA library Guennadi Liakhovetski
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