[PATCH i-g-t v4 2/5] lib: Add more debug messages to error paths

[Kamil Konieczny]

Hi Janusz,
On 2024-07-18 at 10:55:13 +0200, Janusz Krzysztofik wrote:
> On an attempt to resolve the issue of mysteriously failing updates of
> sysfs entries representing engine preempt timeout values, add debug
> messages to error paths of involved library functions.
> 
> v2: No changes.
> v3: Add still more debug messages.
> v4: Fix missing line termination.
> 
> Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/6268
> Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>

Reviewed-by: Kamil Konieczny <kamil.konieczny at linux.intel.com>

> ---
>  lib/i915/gem_engine_topology.c | 19 +++++++++++--------
>  lib/igt_sysfs.c                |  4 ++--
>  2 files changed, 13 insertions(+), 10 deletions(-)
> 
> diff --git a/lib/i915/gem_engine_topology.c b/lib/i915/gem_engine_topology.c
> index afb576afb2..c878e95f08 100644
> --- a/lib/i915/gem_engine_topology.c
> +++ b/lib/i915/gem_engine_topology.c
> @@ -454,12 +454,12 @@ static int __open_primary(int dir)
>  	int len;
>  
>  	fd = openat(dir, "dev", O_RDONLY);
> -	if (fd < 0)
> +	if (igt_debug_on(fd < 0))
>  		return dir;
>  
>  	len = read(fd, buf, sizeof(buf) - 1);
>  	close(fd);
> -	if (len <= 0)
> +	if (igt_debug_on(len <= 0))
>  		return dir;
>  	buf[len] = '\0';
>  
> @@ -467,7 +467,7 @@ static int __open_primary(int dir)
>  	if (minor < 64)
>  		return dir;
>  
> -	if (readlinkat(dir, "device", target, sizeof(target)) < 0)
> +	if (igt_debug_on(readlinkat(dir, "device", target, sizeof(target)) < 0))
>  		return dir;
>  
>  	fd = openat(dir, "..", O_RDONLY);
> @@ -500,24 +500,27 @@ static FILE *__open_attr(int dir, const char *mode, ...)
>  	va_list ap;
>  
>  	/* The attributes are not to be found on render nodes */
> -	dir = __open_primary(dir);
> +	igt_debug_on((dir = __open_primary(dir)) < 0);
>  
>  	va_start(ap, mode);
>  	while (dir >= 0 && (path = va_arg(ap, const char *))) {
>  		int fd;
>  
> -		fd = openat(dir, path, O_RDONLY);
> +		igt_debug_on_f((fd = openat(dir, path, O_RDONLY)) < 0,
> +			       "failed component: %s\n", path);
>  		close(dir);
>  
>  		dir = fd;
>  	}
>  	va_end(ap);
> +	if (dir < 0)
> +		return NULL;
>  
>  	if (*mode != 'r') /* clumsy, but fun */
> -		dir = reopen(dir, O_RDWR);
> +		igt_debug_on((dir = reopen(dir, O_RDWR)) < 0);
>  
>  	file = fdopen(dir, mode);
> -	if (!file) {
> +	if (igt_debug_on(!file)) {
>  		close(dir);
>  		return NULL;
>  	}
> @@ -554,7 +557,7 @@ int gem_engine_property_printf(int i915, const char *engine, const char *attr,
>  
>  	file = __open_attr(igt_sysfs_open(i915), "w",
>  			   "engine", engine, attr, NULL);
> -	if (!file)
> +	if (igt_debug_on(!file))
>  		return -1;
>  
>  	va_start(ap, fmt);
> diff --git a/lib/igt_sysfs.c b/lib/igt_sysfs.c
> index 42b2af41ab..550472d819 100644
> --- a/lib/igt_sysfs.c
> +++ b/lib/igt_sysfs.c
> @@ -186,7 +186,7 @@ char *igt_sysfs_path(int device, char *path, int pathlen)
>  	snprintf(path, pathlen, "/sys/dev/char/%d:%d",
>  		 major(st.st_rdev), minor(st.st_rdev));
>  
> -	if (access(path, F_OK))
> +	if (igt_debug_on(access(path, F_OK)))
>  		return NULL;
>  
>  	return path;
> @@ -206,7 +206,7 @@ int igt_sysfs_open(int device)
>  {
>  	char path[80];
>  
> -	if (!igt_sysfs_path(device, path, sizeof(path)))
> +	if (igt_debug_on(!igt_sysfs_path(device, path, sizeof(path))))
>  		return -1;
>  
>  	return open(path, O_RDONLY);
> -- 
> 2.45.2
>