Hi Geert-san,
2015-07-15 21:53 GMT+09:00 Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>:
> Hi Kaneko-san, Mizuguchi-san,
>
> On Sun, Jun 14, 2015 at 7:27 PM, Yoshihiro Kaneko <ykaneko0929@xxxxxxxxx> wrote:
>> From: Kazuya Mizuguchi <kazuya.mizuguchi.ks@xxxxxxxxxxx>
>>
>> There is a problem when the sci_dma_rx_complete() is processed
>> before cancel process of work_fn_rx() completes by rx_timer_fn().
>> This patch locks work_fn_rx().
>>
>> Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@xxxxxxxxxxx>
>> Signed-off-by: Yoshihiro Kaneko <ykaneko0929@xxxxxxxxx>
>
> Thanks for your patch!
>
> Unfortunately this is not sufficient. work_fn_rx() may race with
> sci_rx_dma_release(), too.
Thanks for your review!
Your following patch fixes that problem, right?
[PATCH/RFC v2 23/29] serial: sh-sci: Fix race condition between RX
work_struct and cleanup
Thanks,
Kaneko
>
>> ---
>>
>> This patch is based on the tty-next branch of Greg Kroah-Hartman's tty
>> tree.
>>
>> drivers/tty/serial/sh-sci.c | 13 +++++++------
>> 1 file changed, 7 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
>> index b74a644..ef59842 100644
>> --- a/drivers/tty/serial/sh-sci.c
>> +++ b/drivers/tty/serial/sh-sci.c
>> @@ -1423,14 +1423,16 @@ static void work_fn_rx(struct work_struct *work)
>> struct uart_port *port = &s->port;
>> struct dma_async_tx_descriptor *desc;
>> int new;
>> + unsigned long flags;
>>
>> + spin_lock_irqsave(&port->lock, flags);
>> if (s->active_rx == s->cookie_rx[0]) {
>> new = 0;
>> } else if (s->active_rx == s->cookie_rx[1]) {
>> new = 1;
>> } else {
>> dev_err(port->dev, "cookie %d not found!\n", s->active_rx);
>> - return;
>> + goto out;
>> }
>> desc = s->desc_rx[new];
>>
>> @@ -1440,36 +1442,35 @@ static void work_fn_rx(struct work_struct *work)
>> struct dma_chan *chan = s->chan_rx;
>> struct shdma_desc *sh_desc = container_of(desc,
>> struct shdma_desc, async_tx);
>> - unsigned long flags;
>> int count;
>>
>> dmaengine_terminate_all(chan);
>> dev_dbg(port->dev, "Read %zu bytes with cookie %d\n",
>> sh_desc->partial, sh_desc->cookie);
>>
>> - spin_lock_irqsave(&port->lock, flags);
>> count = sci_dma_rx_push(s, sh_desc->partial);
>> - spin_unlock_irqrestore(&port->lock, flags);
>>
>> if (count)
>> tty_flip_buffer_push(&port->state->port);
>>
>> sci_submit_rx(s);
>>
>> - return;
>> + goto out;
>> }
>>
>> s->cookie_rx[new] = desc->tx_submit(desc);
>> if (s->cookie_rx[new] < 0) {
>> dev_warn(port->dev, "Failed submitting Rx DMA descriptor\n");
>> sci_rx_dma_release(s, true);
>> - return;
>> + goto out;
>> }
>>
>> s->active_rx = s->cookie_rx[!new];
>>
>> dev_dbg(port->dev, "%s: cookie %d #%d, new active #%d\n",
>> __func__, s->cookie_rx[new], new, s->active_rx);
>> +out:
>> + spin_unlock_irqrestore(&port->lock, flags);
>> }
>>
>> static void work_fn_tx(struct work_struct *work)
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
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