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.
> ---
>
> 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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