[PATCH] oprofile: disable write access to oprofilefs whileprofiler is running

[Robert Richter]

On 05.10.10 06:36:57, Robert Richter wrote:
> Oprofile counters are setup when profiling is disabled. Thus, writing
> to oprofilefs has no immediate effect. Changes are updated only after
> oprofile is reenabled.
> 
> To keep userland and kernel states synchronized, we now allow
> configuration of oprofile only if profiling is disabled.  In this case
> it checks if the profiler is running and then disables write access to
> oprofilefs by returning -EBUSY. The change should be backward
> compatible with current oprofile userland daemon.
> 
> Cc: Maynard Johnson <maynardj@xxxxxxxxxx>
> Cc: William Cohen <wcohen@xxxxxxxxxx>
> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
> Signed-off-by: Robert Richter <robert.richter@xxxxxxx>
> ---
>  drivers/oprofile/oprof.c          |   19 +++++--------------
>  drivers/oprofile/oprof.h          |    2 +-
>  drivers/oprofile/oprofile_files.c |    7 +++++--
>  drivers/oprofile/oprofilefs.c     |    8 ++++++--
>  4 files changed, 17 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/oprofile/oprof.c b/drivers/oprofile/oprof.c
> index b4a6857..a7ab09e 100644
> --- a/drivers/oprofile/oprof.c
> +++ b/drivers/oprofile/oprof.c
> @@ -225,26 +225,17 @@ post_sync:
>  	mutex_unlock(&start_mutex);
>  }
>  
> -int oprofile_set_backtrace(unsigned long val)
> +int oprofile_set_ulong(unsigned long *addr, unsigned long val)
>  {
> -	int err = 0;
> +	int err = -EBUSY;
>  
>  	mutex_lock(&start_mutex);
> -
>  	if (oprofile_started) {

I did a late change which I never should do. It should be:

	if (!oprofile_started) ...

The concept remains the same.

Updated patch below.

Sorry,

-Robert

> -		err = -EBUSY;
> -		goto out;
> -	}
> -
> -	if (!oprofile_ops.backtrace) {
> -		err = -EINVAL;
> -		goto out;
> +		*addr = val;
> +		err = 0;
>  	}
> -
> -	oprofile_backtrace_depth = val;
> -
> -out:
>  	mutex_unlock(&start_mutex);
> +
>  	return err;
>  }

--