crash-stack: Find crashed tid by wchan

If tid is not offered by kernel, crash-stack would
find crashed tid by checking wchan value of each thread.

Change-Id: Idfd6866fe17af4c7a266b3ae127e39087b0848f0
Signed-off-by: Sunmin Lee <sunm.lee@samsung.com>

1 files changed, 80 insertions, 1 deletions

diff --git a/src/crash-stack/crash-stack.c b/src/crash-stack/crash-stack.c
index 4e51472..3ea471b 100644
--- a/src/crash-stack/crash-stack.c
+++ b/src/crash-stack/crash-stack.c
@@ -800,6 +800,82 @@ static void __crash_stack_print_meminfo(FILE* outputfile, pid_t pid)
 }
 
 /**
+ * @brief Check wchan of thread
+ *
+ * @param pid PID of the inspected process
+ * @param tid TID of the thread to check
+ */
+static int check_thread_wchan(int pid, int tid)
+{
+	int fd, cnt;
+	char path[PATH_MAX], buf[100];
+
+	snprintf(path, PATH_MAX, "/proc/%d/task/%d/wchan", pid, tid);
+	fd = open(path, O_RDONLY);
+	if (fd == -1) {
+		fprintf(errfile, "[crash-stack] cannot open %s\n", path);
+		return -errno;
+	}
+	cnt = read(fd, buf, sizeof(buf));
+	if (cnt == -1 || cnt == sizeof(buf)) {
+		fprintf(errfile, "[crash-stack] read %s error\n", path);
+		close(fd);
+		return -errno;
+	}
+	buf[cnt] = 0;
+	close(fd);
+
+	if (strncmp("do_coredump", buf, sizeof(buf)) == 0)
+		return tid;
+	else
+		return 0;
+}
+
+/**
+ * @brief Find crashed tid if tid was not offered
+ *
+ * @param pid PID of the inspected process
+ */
+static int find_crash_tid(int pid)
+{
+	int threadnum = 1;
+	int crash_tid = -1;
+	DIR *dir;
+	struct dirent entry;
+	struct dirent *dentry = NULL;
+	char task_path[PATH_MAX];
+	struct stat sb;
+
+	snprintf(task_path, PATH_MAX, "/proc/%d/task", pid);
+	if (stat(task_path, &sb) == -1) {
+		return -1;
+	}
+
+	threadnum = sb.st_nlink - 2;
+
+	if (threadnum > 1) {
+		dir = opendir(task_path);
+		if (!dir) {
+			fprintf(errfile, "[crash-stack] cannot open %s\n", task_path);
+			return -1;
+		} else {
+			while (readdir_r(dir, &entry, &dentry) == 0 && dentry) {
+				if (strcmp(dentry->d_name, ".") == 0 ||
+				    strcmp(dentry->d_name, "..") == 0)
+					continue;
+				crash_tid = check_thread_wchan(pid,
+						atoi(dentry->d_name));
+				if (crash_tid > 0)
+					break;
+			}
+			closedir(dir);
+			return crash_tid;
+		}
+	}
+	return -1;
+}
+
+/**
  * @brief Main function.
  *
  * Main module accepts should be launched with:
@@ -841,7 +917,10 @@ int main(int argc, char **argv)
 	if (NULL == errfile) errfile = stderr;
 	if (NULL == outputfile) outputfile = stdout;
 
-	if (tid == 0) tid = pid;
+	if (tid == 0) {
+		if ((tid = find_crash_tid(pid)) < 0)
+			tid = pid;
+	}
 
 	argc -= optind;