Re: [patch V2 07/15] powerpc/ps3: Convert half completion to rcuwait

Sebastian Andrzej Siewior
2020-03-19T09:01:07Z

On 2020-03-18 21:43:09 [+0100], Thomas Gleixner wrote:
> --- a/arch/powerpc/platforms/ps3/device-init.c
> +++ b/arch/powerpc/platforms/ps3/device-init.c
> @@ -725,12 +728,12 @@ static int ps3_notification_read_write(s
> unsigned long flags;
> int res;
>
> - init_completion(&dev->done);
> spin_lock_irqsave(&dev->lock, flags);
> res = write ? lv1_storage_write(dev->sbd.dev_id, 0, 0, 1, 0, lpar,
> &dev->tag)
> : lv1_storage_read(dev->sbd.dev_id, 0, 0, 1, 0, lpar,
> &dev->tag);
> + dev->done = false;
> spin_unlock_irqrestore(&dev->lock, flags);
> if (res) {
> pr_err("%s:%u: %s failed %d\n", __func__, __LINE__, op, res);
> @@ -738,14 +741,10 @@ static int ps3_notification_read_write(s
> }
> pr_debug("%s:%u: notification %s issued\n", __func__, __LINE__, op);
>
> - res = wait_event_interruptible(dev->done.wait,
> - dev->done.done || kthread_should_stop());
> + rcuwait_wait_event(&dev->wait, dev->done || kthread_should_stop(), TASK_IDLE);
> +
…

Not sure it matters but this struct `dev' is allocated on stack. Should
the interrupt fire *before* rcuwait_wait_event() set wait.task to NULL
then it is of random value on the first invocation of rcuwait_wake_up().
->

diff --git a/arch/powerpc/platforms/ps3/device-init.c b/arch/powerpc/platforms/ps3/device-init.c
index 197347c3c0b24..e87360a0fb40d 100644
--- a/arch/powerpc/platforms/ps3/device-init.c
+++ b/arch/powerpc/platforms/ps3/device-init.c
@@ -809,6 +809,7 @@ static int ps3_probe_thread(void *data)
}

spin_lock_init(&dev.lock);
+ rcuwait_init(&dev.wait);

res = request_irq(irq, ps3_notification_interrupt, 0,
"ps3_notification", &dev);

Sebastian