From: Jakub Skokan <jakub.skokan@havefun.cz>
Date: Mon, 11 Jun 2018 13:05:14 +0000 (+0200)
Subject: loadavg: restart thread on library reload
X-Git-Tag: lxcfs-3.1.0~22^2
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=a83618e2cdb9abede47001f2bcb132fc569a0c9b;p=mirror_lxcfs.git

loadavg: restart thread on library reload

Signed-off-by: Jakub Skokan <jakub.skokan@havefun.cz>
---

diff --git a/bindings.c b/bindings.c
index b20eaa0..d03792b 100644
--- a/bindings.c
+++ b/bindings.c
@@ -97,6 +97,7 @@ struct file_info {
  * 1 means use loadavg, 0 means not use.
  */
 static int loadavg = 0;
+static volatile sig_atomic_t loadavg_stop = 0;
 static int calc_hash(char *name)
 {
 	unsigned int hash = 0;
@@ -247,7 +248,7 @@ static struct load_node *del_node(struct load_node *n, int locate)
 	return g;
 }
 
-void load_free(void)
+static void load_free(void)
 {
 	int i;
 	struct load_node *f, *p;
@@ -4500,6 +4501,9 @@ void *load_begin(void *arg)
 	clock_t time1, time2;
 
 	while (1) {
+		if (loadavg_stop == 1)
+			return NULL;
+
 		time1 = clock();
 		for (i = 0; i < LOAD_SIZE; i++) {
 			pthread_mutex_lock(&load_hash[i].lock);
@@ -4536,6 +4540,10 @@ out:					f = f->next;
 				}
 			}
 		}
+
+		if (loadavg_stop == 1)
+			return NULL;
+
 		time2 = clock();
 		usleep(FLUSH_TIME * 1000000 - (int)((time2 - time1) * 1000000 / CLOCKS_PER_SEC));
 	}
@@ -4649,6 +4657,26 @@ pthread_t load_daemon(int load_use)
 	return pid;
 }
 
+/* Returns 0 on success. */
+int stop_load_daemon(pthread_t pid)
+{
+	int s;
+
+	/* Signal the thread to gracefully stop */
+	loadavg_stop = 1;
+
+	s = pthread_join(pid, NULL); /* Make sure sub thread has been canceled. */
+	if (s != 0) {
+		lxcfs_error("%s\n", "stop_load_daemon error: failed to join");
+		return -1;
+	}
+
+	load_free();
+	loadavg_stop = 0;
+
+	return 0;
+}
+
 static off_t get_procfile_size(const char *which)
 {
 	FILE *f = fopen(which, "r");
diff --git a/bindings.h b/bindings.h
index 6563011..f1a4627 100644
--- a/bindings.h
+++ b/bindings.h
@@ -33,6 +33,6 @@ extern int proc_read(const char *path, char *buf, size_t size, off_t offset,
 		struct fuse_file_info *fi);
 extern int proc_access(const char *path, int mask);
 extern pthread_t load_daemon(int load_use);
-extern void load_free(void);
+extern int stop_load_daemon(pthread_t pid);
 
 #endif /* __LXCFS_BINDINGS_H */
diff --git a/lxcfs.c b/lxcfs.c
index fe38148..76b3ea2 100644
--- a/lxcfs.c
+++ b/lxcfs.c
@@ -69,6 +69,46 @@ static void users_unlock(void)
 	unlock_mutex(&user_count_mutex);
 }
 
+static pthread_t loadavg_pid = 0;
+
+/* Returns zero on success */
+static int start_loadavg(void) {
+	char *error;
+	pthread_t (*load_daemon)(int);
+
+	dlerror();    /* Clear any existing error */
+
+	load_daemon = (pthread_t (*)(int)) dlsym(dlopen_handle, "load_daemon");
+	error = dlerror();
+	if (error != NULL) {
+		lxcfs_error("load_daemon fails:%s\n", error);
+		return -1;
+	}
+	loadavg_pid = load_daemon(1);
+	if (loadavg_pid == 0)
+		return -1;
+
+	return 0;
+}
+
+/* Returns zero on success */
+static int stop_loadavg(void) {
+	char *error;
+	int (*stop_load_daemon)(pthread_t);
+
+	stop_load_daemon = (int (*)(pthread_t)) dlsym(dlopen_handle, "stop_load_daemon");
+	error = dlerror();
+	if (error != NULL) {
+		lxcfs_error("stop_load_daemon error: %s\n", error);
+		return -1;
+	}
+
+	if (stop_load_daemon(loadavg_pid) != 0)
+		return -1;
+
+	return 0;
+}
+
 static volatile sig_atomic_t need_reload;
 
 /* do_reload - reload the dynamic library.  Done under
@@ -76,6 +116,10 @@ static volatile sig_atomic_t need_reload;
 static void do_reload(void)
 {
 	char lxcfs_lib_path[PATH_MAX];
+
+	if (loadavg_pid > 0)
+		stop_loadavg();
+
 	if (dlopen_handle) {
 		lxcfs_debug("%s\n", "Closing liblxcfs.so handle.");
 		dlclose(dlopen_handle);
@@ -101,6 +145,9 @@ static void do_reload(void)
 	}
 
 good:
+	if (loadavg_pid > 0)
+		start_loadavg();
+
 	if (need_reload)
 		lxcfs_error("%s\n", "lxcfs: reloaded");
 	need_reload = 0;
@@ -849,12 +896,7 @@ int main(int argc, char *argv[])
 	char *pidfile = NULL, *saveptr = NULL, *token = NULL, *v = NULL;
 	size_t pidfile_len;
 	bool debug = false, nonempty = false;
-	pthread_t pid;
-	int s = 0;
-	char *error;
 	bool load_use = false;
-	pthread_t (*load_daemon)(int);
-	void (*load_free)(void);
 	/*
 	 * what we pass to fuse_main is:
 	 * argv[0] -s [-f|-d] -o allow_other,directio argv[1] NULL
@@ -922,42 +964,13 @@ int main(int argc, char *argv[])
 	if ((pidfd = set_pidfile(pidfile)) < 0)
 		goto out;
 
-	if (load_use == true) {
-		dlerror();    /* Clear any existing error */
+	if (load_use && start_loadavg() != 0)
+		goto out;
 
-		load_daemon = (pthread_t (*)(int)) dlsym(dlopen_handle, "load_daemon");
-		error = dlerror();
-		if (error != NULL) {
-			lxcfs_error("load_daemon fails:%s\n", error);
-			goto out;
-		}
-		pid = load_daemon(1);
-		if (pid == 0)
-			goto out;
-	}
 	if (!fuse_main(nargs, newargv, &lxcfs_ops, NULL))
 		ret = EXIT_SUCCESS;
-	if (load_use == true) {
-		s = pthread_cancel(pid);
-		if (s == 0) {
-			s = pthread_join(pid, NULL); /* Make sure sub thread has been canceled. */
-			if (s != 0) {
-				lxcfs_error("%s\n", "load_free error!");
-				goto out;
-			}
-			dlerror();    /* Clear any existing error */
-
-			load_free = (void (*)(void)) dlsym(dlopen_handle, "load_free");
-			error = dlerror();
-			if (error != NULL) {
-				lxcfs_error("load_free error: %s\n", error);
-				goto out;
-			}
-			load_free();
-		} else {
-			lxcfs_error("%s\n", "load_free error!");
-		}
-	}
+	if (load_use)
+		stop_loadavg();
 
 out:
 	if (dlopen_handle)