On Fri, Jun 08, 2012 at 03:30:23PM +0530, Shilimkar, Santosh wrote:
> On Fri, Jun 8, 2012 at 2:32 PM, Russell King - ARM Linux
> <linux@xxxxxxxxxxxxxxxx> wrote:
> > On Thu, Jun 07, 2012 at 12:06:32PM +0100, Russell King wrote:
> >> Tested-by: Tony Lindgren <tony@xxxxxxxxxxx>
> >> Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
> >> ---
> >> drivers/dma/Kconfig | 6 +
> >> drivers/dma/Makefile | 1 +
> >> drivers/dma/omap-dma.c | 522 ++++++++++++++++++++++++++++++++++++++++++++++
> >> include/linux/omap-dma.h | 24 ++
> >> 4 files changed, 553 insertions(+), 0 deletions(-)
> >> create mode 100644 drivers/dma/omap-dma.c
> >> create mode 100644 include/linux/omap-dma.h
> >
> > There is a bug in here which no one has spotted... I just noticed it.
> >
> > diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c
> > index 500bc71..02eb2fd 100644
> > --- a/drivers/dma/omap-dma.c
> > +++ b/drivers/dma/omap-dma.c
> > @@ -130,14 +130,13 @@ static void omap_dma_callback(int ch, u16 status, void *data)
> >
> > spin_lock_irqsave(&c->vc.lock, flags);
> > d = c->desc;
> > - if (!d)
> > - return;
> > -
> > - if (++c->sgidx < d->sglen) {
> > - omap_dma_start_sg(c, d, c->sgidx);
> > - } else {
> > - omap_dma_start_desc(c);
> > - vchan_cookie_complete(&d->vd);
> > + if (d) {
> > + if (++c->sgidx < d->sglen) {
> > + omap_dma_start_sg(c, d, c->sgidx);
> > + } else {
> > + omap_dma_start_desc(c);
> > + vchan_cookie_complete(&d->vd);
> > + }
> > }
> > spin_unlock_irqrestore(&c->vc.lock, flags);
> > }
> >
> You mean the lock release, right ?
Yes, if c->desc is NULL, we exit this function with the lock held,
which will lead to a lockup.
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