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

[Janusz Krzysztofik]

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>
---
 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