[PATCH i-g-t] lib/igt_kmod: drop devcoredump before a PCI module unload

[Rodrigo Vivi]

devcoredump holds a module reference, blocking the module removal.

It is intentional from the devcoredump perspective to keep the
log available even after the unbind/unprobe. However it blocks
our module removal here.

v2: Accepting many suggestions from Lucas.

Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: José Roberto de Souza <jose.souza at intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 lib/igt_kmod.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/lib/igt_kmod.c b/lib/igt_kmod.c
index cc242838f..14d51f4f6 100644
--- a/lib/igt_kmod.c
+++ b/lib/igt_kmod.c
@@ -323,6 +323,59 @@ static int igt_kmod_unload_r(struct kmod_module *kmod, unsigned int flags)
 	return err;
 }
 
+static void igt_drop_devcoredump(const char *driver)
+{
+	char sysfspath[PATH_MAX];
+	DIR *dir;
+	char *devcoredump;
+	FILE *data;
+	struct dirent *entry;
+	int len, ret;
+
+	len = snprintf(sysfspath, sizeof(sysfspath),
+		       "/sys/bus/pci/drivers/%s", driver);
+
+	igt_assert(len < sizeof(sysfspath));
+
+	 /* Not a PCI module */
+	if (access(sysfspath, F_OK))
+		return;
+
+	devcoredump = sysfspath + len;
+
+	dir = opendir(sysfspath);
+	igt_assert(dir);
+
+	while ((entry = readdir(dir)) != NULL) {
+		if (entry->d_type != DT_LNK ||
+		    strcmp(entry->d_name, ".") == 0 ||
+		    strcmp(entry->d_name, "..") == 0)
+			continue;
+
+		ret = snprintf(devcoredump, sizeof(sysfspath) - len,
+			       "/%s/devcoredump", entry->d_name);
+
+		igt_assert(ret < sizeof(sysfspath) - len);
+
+		if (access(sysfspath, F_OK) != -1) {
+			igt_info("Removing devcoredump before module unload: %s\n",
+				 sysfspath);
+
+			strcat(sysfspath, "/data");
+			data = fopen(sysfspath, "w");
+			igt_assert(data);
+
+			/*
+			 * Write anything to devcoredump/data to
+			 * force its deletion
+			 */
+			fprintf(data, "1\n");
+			fclose(data);
+		}
+	}
+	closedir(dir);
+}
+
 /**
  * igt_kmod_unload:
  * @mod_name: Module name.
@@ -341,6 +394,8 @@ igt_kmod_unload(const char *mod_name, unsigned int flags)
 	struct kmod_module *kmod;
 	int err;
 
+	igt_drop_devcoredump(mod_name);
+
 	err = kmod_module_new_from_name(ctx, mod_name, &kmod);
 	if (err < 0) {
 		igt_debug("Could not use module %s (%s)\n", mod_name,
-- 
2.44.0