watchdog: add support for starting/stopping kernel watchdog

Extend the ubus watchdog cmd with the parameter magicclose; when set and
in case the stopped parameter is enabled the kernel watchdog will be stopped
by first sending the magic character 'V' followed by a close of the watchdog
fd. In case stopped is set to disabled the watchdog fd will be created again.

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>
Acked-by: John Crispin <john@phrozen.org>

diff --git a/system.c b/system.c
index 6e85ad7..6cd2b62 100644 (file)
--- a/system.c
+++ b/system.c
@@ -279,6 +279,7 @@ static int system_reboot(struct ubus_context *ctx, struct ubus_object *obj,
 enum {
        WDT_FREQUENCY,
        WDT_TIMEOUT,
+       WDT_MAGICCLOSE,
        WDT_STOP,
        __WDT_MAX
 };
@@ -286,6 +287,7 @@ enum {
 static const struct blobmsg_policy watchdog_policy[__WDT_MAX] = {
        [WDT_FREQUENCY] = { .name = "frequency", .type = BLOBMSG_TYPE_INT32 },
        [WDT_TIMEOUT] = { .name = "timeout", .type = BLOBMSG_TYPE_INT32 },
+       [WDT_MAGICCLOSE] = { .name = "magicclose", .type = BLOBMSG_TYPE_BOOL },
        [WDT_STOP] = { .name = "stop", .type = BLOBMSG_TYPE_BOOL },
 };
 
@@ -320,6 +322,9 @@ static int watchdog_set(struct ubus_context *ctx, struct ubus_object *obj,
                 watchdog_timeout(timeout);
        }
 
+       if (tb[WDT_MAGICCLOSE])
+               watchdog_set_magicclose(blobmsg_get_bool(tb[WDT_MAGICCLOSE]));
+
        if (tb[WDT_STOP])
                watchdog_set_stopped(blobmsg_get_bool(tb[WDT_STOP]));
 
@@ -334,6 +339,7 @@ static int watchdog_set(struct ubus_context *ctx, struct ubus_object *obj,
        blobmsg_add_string(&b, "status", status);
        blobmsg_add_u32(&b, "timeout", watchdog_timeout(0));
        blobmsg_add_u32(&b, "frequency", watchdog_frequency(0));
+       blobmsg_add_u8(&b, "magicclose", watchdog_get_magicclose());
        ubus_send_reply(ctx, req, b.head);
 
        return 0;

diff --git a/watchdog.c b/watchdog.c
index 780b321..97c8337 100644 (file)
--- a/watchdog.c
+++ b/watchdog.c
@@ -31,6 +31,7 @@
 static struct uloop_timeout wdt_timeout;
 static int wdt_fd = -1;
 static int wdt_frequency = 5;
+static bool wdt_magicclose = false;
 
 void watchdog_ping(void)
 {
@@ -45,12 +46,66 @@ static void watchdog_timeout_cb(struct uloop_timeout *t)
        uloop_timeout_set(t, wdt_frequency * 1000);
 }
 
+static int watchdog_open(bool cloexec)
+{
+       char *env = getenv("WDTFD");
+
+       if (wdt_fd >= 0)
+               return wdt_fd;
+
+       if (env) {
+               DEBUG(2, "Watchdog handover: fd=%s\n", env);
+               wdt_fd = atoi(env);
+               unsetenv("WDTFD");
+       } else {
+               wdt_fd = open(WDT_PATH, O_WRONLY);
+       }
+
+       if (wdt_fd < 0)
+               return wdt_fd;
+
+       if (cloexec)
+               fcntl(wdt_fd, F_SETFD, fcntl(wdt_fd, F_GETFD) | FD_CLOEXEC);
+
+       return wdt_fd;
+}
+
+static void watchdog_close(void)
+{
+       if (wdt_fd < 0)
+               return;
+
+       if (write(wdt_fd, "V", 1) < 0)
+               ERROR("WDT failed to write release: %s\n", strerror(errno));
+
+       if (close(wdt_fd) == -1)
+               ERROR("WDT failed to close watchdog: %s\n", strerror(errno));
+
+       wdt_fd = -1;
+}
+
+void watchdog_set_magicclose(bool val)
+{
+       wdt_magicclose = val;
+}
+
+bool watchdog_get_magicclose(void)
+{
+       return wdt_magicclose;
+}
+
 void watchdog_set_stopped(bool val)
 {
-       if (val)
+       if (val) {
                uloop_timeout_cancel(&wdt_timeout);
-       else
+
+               if (wdt_magicclose)
+                       watchdog_close();
+       }
+       else {
+               watchdog_open(true);
                watchdog_timeout_cb(&wdt_timeout);
+       }
 }
 
 bool watchdog_get_stopped(void)
@@ -98,26 +153,11 @@ char* watchdog_fd(void)
 
 void watchdog_init(int preinit)
 {
-       char *env = getenv("WDTFD");
-
-       if (wdt_fd >= 0)
-               return;
-
        wdt_timeout.cb = watchdog_timeout_cb;
-       if (env) {
-               DEBUG(2, "Watchdog handover: fd=%s\n", env);
-               wdt_fd = atoi(env);
-               unsetenv("WDTFD");
-       } else {
-               wdt_fd = open("/dev/watchdog", O_WRONLY);
-       }
 
-       if (wdt_fd < 0)
+       if (watchdog_open(!preinit) < 0)
                return;
 
-       if (!preinit)
-               fcntl(wdt_fd, F_SETFD, fcntl(wdt_fd, F_GETFD) | FD_CLOEXEC);
-
        LOG("- watchdog -\n");
        watchdog_timeout(30);
        watchdog_timeout_cb(&wdt_timeout);

diff --git a/watchdog.h b/watchdog.h
index 3c4a487..fd9aed2 100644 (file)
--- a/watchdog.h
+++ b/watchdog.h
@@ -22,6 +22,8 @@ void watchdog_init(int preinit);
 char* watchdog_fd(void);
 int watchdog_timeout(int timeout);
 int watchdog_frequency(int frequency);
+void watchdog_set_magicclose(bool val);
+bool watchdog_get_magicclose(void);
 void watchdog_set_stopped(bool val);
 bool watchdog_get_stopped(void);
 void watchdog_set_cloexec(bool val);
@@ -46,6 +48,14 @@ static inline int watchdog_frequency(int frequency)
        return 0;
 }
 
+static inline void watchdog_set_magicclose(bool val)
+{
+}
+
+static inline void watchdog_get_magicclose(bool val)
+{
+}
+
 static inline void watchdog_set_stopped(bool val)
 {
 }