Re: [PATCH i-g-t v6 1/2] lib/igt_sysfs: Implement dynamic adjustment of debug log level

["Modem, Bhanuprakash" <bhanuprakash.modem@intel.com>]

On 12-07-2024 01:59 pm, Pranay Samala wrote:
> Adjust debug log levels dynamically to prevent machine
> disk overflow during excessive test debug logs.
> 
> Introduce function to modify log levels as needed,
> with an exit handler restoring default settings post-test.
> 
> v2:
> - Using proper function name to represent its
>    functionality (Bhanu)
> - Added Documentation for each functions (Bhanu)
> - Removed the magic number and instead reading the
>    default value first (Bhanu)
> - Using recommended apis for better handling (Bhanu)
> 
> v3:
> - Adding module drm_open_param function to open
>    the sysfs directory (Bhanu)
> - Reducing the current drm loglevel by step value
>    to make it more robust (Bhanu)
> 
> v4:
> - Remove all the extra new lines (Bhanu)
> - Remove the unused declaration (Bhanu)
> - Edit API to only update the requested drm debug
>    log value from the caller (Bhanu)
> 
> v5:
> - Add TODO for multiple exit handler installation
> 
> Signed-off-by: Pranay Samala <pranay.samala@intel.com>
Reviewed-by: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
> ---
>   lib/igt_sysfs.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++++
>   lib/igt_sysfs.h |   5 +++
>   2 files changed, 113 insertions(+)
> 
> diff --git a/lib/igt_sysfs.c b/lib/igt_sysfs.c
> index ffeec1ca2..42b2af41a 100644
> --- a/lib/igt_sysfs.c
> +++ b/lib/igt_sysfs.c
> @@ -412,6 +412,114 @@ int igt_sysfs_get_num_gt(int device)
>   	return num_gts;
>   }
>   
> +/**
> + * igt_sysfs_drm_module_params_open:
> + *
> + * This opens the sysfs directory corresponding to drm module
> + * parameters.
> + *
> + * Returns:
> + * The directory fd, or -1 on failure.
> + */
> +int igt_sysfs_drm_module_params_open(void)
> +{
> +	char path[] = "/sys/module/drm/parameters";
> +
> +	if (access(path, F_OK))
> +		return -1;
> +
> +	return open(path, O_RDONLY);
> +}
> +
> +static int log_level = -1;
> +
> +/**
> + * igt_drm_debug_level_get:
> + *
> + * This reads the current debug log level of the machine on
> + * which the test is currently executing.
> + *
> + * Returns:
> + * The current log level, or -1 on error.
> + */
> +int igt_drm_debug_level_get(int dir)
> +{
> +	char buf[20];
> +
> +	if (log_level >= 0)
> +		return log_level;
> +
> +	if (igt_sysfs_read(dir, "debug", buf, sizeof(buf) - 1) < 0)
> +		return -1;
> +
> +	return atoi(buf);
> +}
> +
> +/**
> + * igt_drm_debug_level_reset:
> + *
> + * This modifies the current debug log level of the machine
> + * to the default value post-test.
> + *
> + */
> +void igt_drm_debug_level_reset(void)
> +{
> +	char buf[20];
> +	int dir;
> +
> +	if (log_level < 0)
> +		return;
> +
> +	dir = igt_sysfs_drm_module_params_open();
> +	if (dir < 0)
> +		return;
> +
> +	igt_debug("Resetting DRM debug level to %d\n", log_level);
> +	snprintf(buf, sizeof(buf), "%d", log_level);
> +	igt_assert(igt_sysfs_set(dir, "debug", buf));
> +
> +	close(dir);
> +}
> +
> +static void igt_drm_debug_level_reset_exit_handler(int sig)
> +{
> +	igt_drm_debug_level_reset();
> +}
> +
> +/**
> + * igt_drm_debug_level_update:
> + * @debug_level: new debug level to set
> + *
> + * This modifies the current drm debug log level to the new value.
> + */
> +void igt_drm_debug_level_update(unsigned int new_log_level)
> +{
> +	char buf[20];
> +	int dir;
> +
> +	dir = igt_sysfs_drm_module_params_open();
> +	if (dir < 0)
> +		return;
> +
> +	log_level = igt_drm_debug_level_get(dir);
> +	if (log_level < 0) {
> +		close(dir);
> +		return;
> +	}
> +
> +	igt_debug("Setting DRM debug level to %d\n", new_log_level);
> +	snprintf(buf, sizeof(buf), "%d", new_log_level);
> +	igt_assert(igt_sysfs_set(dir, "debug", buf));
> +
> +	close(dir);
> +
> +	/*
> +	 * TODO: Check whether multiple exit handlers will get installed,
> +	 * if we call this api multiple times
> +	 */
> +	igt_install_exit_handler(igt_drm_debug_level_reset_exit_handler);
> +}
> +
>   /**
>    * igt_sysfs_write:
>    * @dir: sysfs directory
> diff --git a/lib/igt_sysfs.h b/lib/igt_sysfs.h
> index 6c604d939..5d050c786 100644
> --- a/lib/igt_sysfs.h
> +++ b/lib/igt_sysfs.h
> @@ -138,6 +138,11 @@ void igt_sysfs_set_boolean(int dir, const char *attr, bool value);
>   void bind_fbcon(bool enable);
>   void fbcon_blink_enable(bool enable);
>   
> +void igt_drm_debug_level_update(unsigned int new_log_level);
> +void igt_drm_debug_level_reset(void);
> +int igt_drm_debug_level_get(int dir);
> +int igt_sysfs_drm_module_params_open(void);
> +
>   /**
>    * igt_sysfs_rw_attr:
>    * @dir: file descriptor for parent directory