On Thu, 2014-06-26 at 09:46 +0200, Federico Vaga wrote:
> In some conditions (echo or particular sequence of special
> characters), on buffer push, the tty layer calls the write operation
> while we are holding the spinlock. This means deadlock within the same
> process on kernels version < 3.12. It seems not a problem on recent
> kernel, but the patch still valid as locking optimization.
>
> The protected variables by the spinlock are: xmit_buf, nb_bytes,
> pointer_read and pointer_write. So, this patch reduces the locked area
> in the IRQ handler only to these variables. Most of the code inside the
> locked area in the IRQ handler is not protected elsewhere; it means
> that it is not protected at all.
>
> Signed-off-by: Federico Vaga <federico.v...@cern.ch>
> ---
> drivers/ipack/devices/ipoctal.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/ipack/devices/ipoctal.c b/drivers/ipack/devices/ipoctal.c
> index 141094e..69687f1 100644
> --- a/drivers/ipack/devices/ipoctal.c
> +++ b/drivers/ipack/devices/ipoctal.c
> @@ -177,19 +177,20 @@ static void ipoctal_irq_tx(struct ipoctal_channel
> *channel)
> if (channel->nb_bytes == 0)
> return;
>
> + spin_lock(&channel->lock);
> value = channel->tty_port.xmit_buf[*pointer_write];
> iowrite8(value, &channel->regs->w.thr);
> channel->stats.tx++;
> (*pointer_write)++;
> *pointer_write = *pointer_write % PAGE_SIZE;
> channel->nb_bytes--;
> + spin_unlock(&channel->lock);
> }
>
> static void ipoctal_irq_channel(struct ipoctal_channel *channel)
> {
> u8 isr, sr;
>
> - spin_lock(&channel->lock);
> /* The HW is organized in pair of channels. See which register we need
> * to read from */
> isr = ioread8(&channel->block_regs->r.isr);
> @@ -213,8 +214,6 @@ static void ipoctal_irq_channel(struct ipoctal_channel
> *channel)
> /* TX of each character */
> if ((isr & channel->isr_tx_rdy_mask) && (sr & SR_TX_READY))
> ipoctal_irq_tx(channel);
> -
> - spin_unlock(&channel->lock);
> }
>
> static irqreturn_t ipoctal_irq_handler(void *arg)Acked-by: Samuel Iglesias Gonsalvez <sigles...@igalia.com> Sam
signature.asc
Description: This is a digitally signed message part
------------------------------------------------------------------------------ Open source business process management suite built on Java and Eclipse Turn processes into business applications with Bonita BPM Community Edition Quickly connect people, data, and systems into organized workflows Winner of BOSSIE, CODIE, OW2 and Gartner awards http://p.sf.net/sfu/Bonitasoft
_______________________________________________ Industrypack-devel mailing list Industrypack-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/industrypack-devel
