Hi Xiaoming,
Xiaoming Ni <nixiaoming@xxxxxxxxxx> wrote on Mon, 7 Dec 2020 18:48:33
+0800:
> ping
>
> On 2020/11/27 21:07, Xiaoming Ni wrote:
> > When CONFIG_MTD_XIP=y, local_irq_disable() is called in xip_disable().
> > To avoid sleep in interrupt context, we need to call local_irq_enable()
> > before schedule().
> >
> > The problem call stack is as follows:
> > bug1:
> > do_write_oneword_retry()
> > xip_disable()
> > local_irq_disable()
> > do_write_oneword_once()
> > schedule()
> > bug2:
> > do_write_buffer()
> > xip_disable()
> > local_irq_disable()
> > do_write_buffer_wait()
> > schedule()
> > bug3:
> > do_erase_chip()
> > xip_disable()
> > local_irq_disable()
> > schedule()
> > bug4:
> > do_erase_oneblock()
> > xip_disable()
> > local_irq_disable()
> > schedule()
> >
> > Fixes: 02b15e343aee ("[MTD] XIP for AMD CFI flash.")
> > Cc: stable@xxxxxxxxxxxxxxx # v2.6.13
> > Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
> > ---
> > drivers/mtd/chips/cfi_cmdset_0002.c | 16 ++++++++++++++++
> > 1 file changed, 16 insertions(+)
> >
> > diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
> > index a1f3e1031c3d..12c3776f093a 100644
> > --- a/drivers/mtd/chips/cfi_cmdset_0002.c
> > +++ b/drivers/mtd/chips/cfi_cmdset_0002.c
> > @@ -1682,7 +1682,11 @@ static int __xipram do_write_oneword_once(struct map_info *map,
> > set_current_state(TASK_UNINTERRUPTIBLE);
> > add_wait_queue(&chip->wq, &wait);
> > mutex_unlock(&chip->mutex);
> > + if (IS_ENABLED(CONFIG_MTD_XIP))
> > + local_irq_enable();
> > schedule();
> > + if (IS_ENABLED(CONFIG_MTD_XIP))
> > + local_irq_disable();
The fix really seems strange to me. I will let Vignesh decide but I
think we should consider updating/fixing xip_disable instead.
> > remove_wait_queue(&chip->wq, &wait);
> > timeo = jiffies + (HZ / 2); /* FIXME */
> > mutex_lock(&chip->mutex);
> > @@ -1962,7 +1966,11 @@ static int __xipram do_write_buffer_wait(struct map_info *map,
> > set_current_state(TASK_UNINTERRUPTIBLE);
> > add_wait_queue(&chip->wq, &wait);
> > mutex_unlock(&chip->mutex);
> > + if (IS_ENABLED(CONFIG_MTD_XIP))
> > + local_irq_enable();
> > schedule();
> > + if (IS_ENABLED(CONFIG_MTD_XIP))
> > + local_irq_disable();
> > remove_wait_queue(&chip->wq, &wait);
> > timeo = jiffies + (HZ / 2); /* FIXME */
> > mutex_lock(&chip->mutex);
> > @@ -2461,7 +2469,11 @@ static int __xipram do_erase_chip(struct map_info *map, struct flchip *chip)
> > set_current_state(TASK_UNINTERRUPTIBLE);
> > add_wait_queue(&chip->wq, &wait);
> > mutex_unlock(&chip->mutex);
> > + if (IS_ENABLED(CONFIG_MTD_XIP))
> > + local_irq_enable();
> > schedule();
> > + if (IS_ENABLED(CONFIG_MTD_XIP))
> > + local_irq_disable();
> > remove_wait_queue(&chip->wq, &wait);
> > mutex_lock(&chip->mutex);
> > continue;
> > @@ -2560,7 +2572,11 @@ static int __xipram do_erase_oneblock(struct map_info *map, struct flchip *chip,
> > set_current_state(TASK_UNINTERRUPTIBLE);
> > add_wait_queue(&chip->wq, &wait);
> > mutex_unlock(&chip->mutex);
> > + if (IS_ENABLED(CONFIG_MTD_XIP))
> > + local_irq_enable();
> > schedule();
> > + if (IS_ENABLED(CONFIG_MTD_XIP))
> > + local_irq_disable();
> > remove_wait_queue(&chip->wq, &wait);
> > mutex_lock(&chip->mutex);
> > continue;
> >
>
Thanks,
Miquèl
