tracecmd_stack_tracer_status() function reads the stack tracer status
from the proc file system. It does not depend on trace-cmd context and
can be used standalone. The function is moved from trace-cmd application
into libtracecmd.
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
---
lib/trace-cmd/trace-util.c | 49 +++++++++++++++++++++++++++++++++
tracecmd/trace-stack.c | 56 ++------------------------------------
2 files changed, 51 insertions(+), 54 deletions(-)
diff --git a/lib/trace-cmd/trace-util.c b/lib/trace-cmd/trace-util.c
index 8c1a0a0..d16a018 100644
--- a/lib/trace-cmd/trace-util.c
+++ b/lib/trace-cmd/trace-util.c
@@ -25,6 +25,7 @@
#define LOCAL_PLUGIN_DIR ".trace-cmd/plugins"
#define TRACEFS_PATH "/sys/kernel/tracing"
#define DEBUGFS_PATH "/sys/kernel/debug"
+#define PROC_STACK_FILE "/proc/sys/kernel/stack_tracer_enabled"
int tracecmd_disable_sys_plugins;
int tracecmd_disable_plugins;
@@ -1787,3 +1788,51 @@ int trace_set_log_file(char *logfile)
return 0;
}
+/**
+ * tracecmd_stack_tracer_status - Check stack trace status
+ * @status: Returned stack trace status:
+ * 0 - not configured, disabled
+ * non 0 - enabled
+ *
+ * Returns -1 in case of an error, 0 if file does not exist
+ * (stack tracer not enabled) or 1 on successful completion.
+ */
+int tracecmd_stack_tracer_status(int *status)
+{
+ struct stat stat_buf;
+ char buf[64];
+ long num;
+ int fd;
+ int n;
+
+ if (stat(PROC_STACK_FILE, &stat_buf) < 0) {
+ /* stack tracer not configured on running kernel */
+ *status = 0; /* not configured means disabled */
+ return 0;
+ }
+
+ fd = open(PROC_STACK_FILE, O_RDONLY);
+
+ if (fd < 0)
+ return -1;
+
+ n = read(fd, buf, sizeof(buf));
+ close(fd);
+
+ if (n <= 0)
+ return -1;
+
+ if (n >= sizeof(buf))
+ return -1;
+
+ buf[n] = 0;
+ errno = 0;
+ num = strtol(buf, NULL, 10);
+
+ /* Check for various possible errors */
+ if (num > INT_MAX || num < INT_MIN || (!num && errno))
+ return -1;
+
+ *status = num;
+ return 1; /* full success */
+}
diff --git a/tracecmd/trace-stack.c b/tracecmd/trace-stack.c
index 34b3b58..bb002c0 100644
--- a/tracecmd/trace-stack.c
+++ b/tracecmd/trace-stack.c
@@ -36,58 +36,6 @@ static void test_available(void)
die("stack tracer not configured on running kernel");
}
-/*
- * Returns:
- * -1 - Something went wrong
- * 0 - File does not exist (stack tracer not enabled)
- * 1 - Success
- */
-static int read_proc(int *status)
-{
- struct stat stat_buf;
- char buf[64];
- long num;
- int fd;
- int n;
-
- if (stat(PROC_FILE, &stat_buf) < 0) {
- /* stack tracer not configured on running kernel */
- *status = 0; /* not configured means disabled */
- return 0;
- }
-
- fd = open(PROC_FILE, O_RDONLY);
-
- if (fd < 0)
- return -1;
-
- n = read(fd, buf, sizeof(buf));
- close(fd);
-
- if (n <= 0)
- return -1;
-
- if (n >= sizeof(buf))
- return -1;
-
- buf[n] = 0;
- errno = 0;
- num = strtol(buf, NULL, 10);
-
- /* Check for various possible errors */
- if (num > INT_MAX || num < INT_MIN || (!num && errno))
- return -1;
-
- *status = num;
- return 1; /* full success */
-}
-
-/* Public wrapper of read_proc() */
-int tracecmd_stack_tracer_status(int *status)
-{
- return read_proc(status);
-}
-
/* NOTE: this implementation only accepts new_status in the range [0..9]. */
static void change_stack_tracer_status(unsigned new_status)
{
@@ -102,7 +50,7 @@ static void change_stack_tracer_status(unsigned new_status)
return;
}
- ret = read_proc(&status);
+ ret = tracecmd_stack_tracer_status(&status);
if (ret < 0)
die("error reading %s", PROC_FILE);
@@ -160,7 +108,7 @@ static void read_trace(void)
size_t n;
int r;
- if (read_proc(&status) <= 0)
+ if (tracecmd_stack_tracer_status(&status) <= 0)
die("Invalid stack tracer state");
if (status > 0)
--
2.21.0
|