This reverts commit 938ba4084abcf6fdd21d9078513c52f8fb9b00d0.

The wait queue @log_wait never has exclusive waiters, so there
is no need to use wake_up_interruptible_all(). Using
wake_up_interruptible() was the correct function to wake all
waiters.

Since there are no exclusive waiters, erroneously changing
wake_up_interruptible() to wake_up_interruptible_all() did not
result in any behavior change. However, using
wake_up_interruptible_all() on a wait queue without exclusive
waiters is fundamentally wrong.

Go back to using wake_up_interruptible() to wake all waiters.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 kernel/printk/printk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index a3e1035929b0..ea3dd55709e7 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3904,7 +3904,7 @@ static void wake_up_klogd_work_func(struct irq_work *irq_work)
 	}
 
 	if (pending & PRINTK_PENDING_WAKEUP)
-		wake_up_interruptible_all(&log_wait);
+		wake_up_interruptible(&log_wait);
 }
 
 static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) =
-- 
2.30.2

On Thu 2022-05-26 22:36:56, John Ogness wrote:
> This reverts commit 938ba4084abcf6fdd21d9078513c52f8fb9b00d0.
> 
> The wait queue @log_wait never has exclusive waiters, so there
> is no need to use wake_up_interruptible_all(). Using
> wake_up_interruptible() was the correct function to wake all
> waiters.
> 
> Since there are no exclusive waiters, erroneously changing
> wake_up_interruptible() to wake_up_interruptible_all() did not
> result in any behavior change. However, using
> wake_up_interruptible_all() on a wait queue without exclusive
> waiters is fundamentally wrong.
> 
> Go back to using wake_up_interruptible() to wake all waiters.
> 
> Signed-off-by: John Ogness <john.ogness@linutronix.de>

The patch has been committed into printk/linux.git, branch
rework/printk.

I am going to create the pull request the following week
after it gets at least one spin in linux-next.

It is trivial patch so that it might be sent directly.
But it does not affect the functionality and is is not
urgent either.

Best Regards,
Petr

On Thu, 26 May 2022 22:36:56 +0206
John Ogness <john.ogness@linutronix.de> wrote:

> This reverts commit 938ba4084abcf6fdd21d9078513c52f8fb9b00d0.
> 
> The wait queue @log_wait never has exclusive waiters, so there
> is no need to use wake_up_interruptible_all(). Using
> wake_up_interruptible() was the correct function to wake all
> waiters.
> 
> Since there are no exclusive waiters, erroneously changing
> wake_up_interruptible() to wake_up_interruptible_all() did not
> result in any behavior change. However, using
> wake_up_interruptible_all() on a wait queue without exclusive
> waiters is fundamentally wrong.
> 
> Go back to using wake_up_interruptible() to wake all waiters.

(Just to show that I have been paying attention ;-)

Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>

-- Steve

> 
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
> ---
>  kernel/printk/printk.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index a3e1035929b0..ea3dd55709e7 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -3904,7 +3904,7 @@ static void wake_up_klogd_work_func(struct irq_work *irq_work)
>  	}
>  
>  	if (pending & PRINTK_PENDING_WAKEUP)
> -		wake_up_interruptible_all(&log_wait);
> +		wake_up_interruptible(&log_wait);
>  }
>  
>  static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) =