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.

Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/6268
Signed-off-by: Janusz Krzysztofik <janusz.krzyszto...@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..3e9bdf2e0a 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", 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

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