[PATCH] posix clocks: correct error value in posix_clock_poll()

[PATCH] posix clocks: correct error value in posix_clock_poll()

[Nicolas Kaiser]

Signed-off-by: Nicolas Kaiser <nikai@nikai.net>
---
It looks to me like -ENODEV might not be a good return value
in poll(). Would POLLERR be the correct one in this case?

 kernel/time/posix-clock.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
index c340ca6..2424d3f 100644
--- a/kernel/time/posix-clock.c
+++ b/kernel/time/posix-clock.c
@@ -71,7 +71,7 @@ static unsigned int posix_clock_poll(struct file *fp, poll_table *wait)
 	int result = 0;
 
 	if (!clk)
-		return -ENODEV;
+		return POLLERR;
 
 	if (clk->ops.poll)
 		result = clk->ops.poll(clk, fp, wait);
-- 
1.7.5.rc3

Re: [PATCH] posix clocks: correct error value in posix_clock_poll()

[Richard Cochran]

On Tue, May 24, 2011 at 12:51:47PM +0200, Nicolas Kaiser wrote:
> Signed-off-by: Nicolas Kaiser <nikai@nikai.net>
> ---
> It looks to me like -ENODEV might not be a good return value
> in poll(). Would POLLERR be the correct one in this case?
> 
>  kernel/time/posix-clock.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
> index c340ca6..2424d3f 100644
> --- a/kernel/time/posix-clock.c
> +++ b/kernel/time/posix-clock.c
> @@ -71,7 +71,7 @@ static unsigned int posix_clock_poll(struct file *fp, poll_table *wait)
>  	int result = 0;
>  
>  	if (!clk)
> -		return -ENODEV;
> +		return POLLERR;

The condition (!clk) is only satisfied when 'zombie' is set,
indicating that the dynamic clock has disappeared. That is why the
file operations uniformly return ENODEV. So, I think it makes sense
the way that it is.

In addition, man 2 poll says,

   POLLERR
          Error condition (output only).

so using that error code would be misleading, IMHO.

Thanks,
Richard

Re: [PATCH] posix clocks: correct error value in posix_clock_poll()

[Nicolas Kaiser]

* Richard Cochran <richardcochran@gmail.com>:
> On Tue, May 24, 2011 at 12:51:47PM +0200, Nicolas Kaiser wrote:
> > It looks to me like -ENODEV might not be a good return value
> > in poll(). Would POLLERR be the correct one in this case?

> The condition (!clk) is only satisfied when 'zombie' is set,
> indicating that the dynamic clock has disappeared. That is why the
> file operations uniformly return ENODEV. So, I think it makes sense
> the way that it is.
> 
> In addition, man 2 poll says,
> 
>    POLLERR
>           Error condition (output only).
> 
> so using that error code would be misleading, IMHO.

I see. Sorry for the noise.

Best regards,
Nicolas Kaiser