watchdog: allow a device path to be specified

Currently systemd hardcodes the use of /dev/watchdog. This is a legacy
chardev that points to watchdog0 in the system.

Modify the watchdog API to allow a different device path to be passed
and stored. Opening the watchdog defaults to /dev/watchdog, maintaining
existing behavior.

diff --git a/src/shared/watchdog.c b/src/shared/watchdog.c
index a6a356d..b0a422d 100644 (file)
--- a/src/shared/watchdog.c
+++ b/src/shared/watchdog.c
@@ -27,10 +27,12 @@
 
 #include "fd-util.h"
 #include "log.h"
+#include "string-util.h"
 #include "time-util.h"
 #include "watchdog.h"
 
 static int watchdog_fd = -1;
+static char *watchdog_device = NULL;
 static usec_t watchdog_timeout = USEC_INFINITY;
 
 static int update_timeout(void) {
@@ -84,7 +86,8 @@ static int open_watchdog(void) {
         if (watchdog_fd >= 0)
                 return 0;
 
-        watchdog_fd = open("/dev/watchdog", O_WRONLY|O_CLOEXEC);
+        watchdog_fd = open(watchdog_device ?: "/dev/watchdog",
+                           O_WRONLY|O_CLOEXEC);
         if (watchdog_fd < 0)
                 return -errno;
 
@@ -96,6 +99,10 @@ static int open_watchdog(void) {
         return update_timeout();
 }
 
+int watchdog_set_device(char *path) {
+        return free_and_strdup(&watchdog_device, path);
+}
+
 int watchdog_set_timeout(usec_t *usec) {
         int r;
 

diff --git a/src/shared/watchdog.h b/src/shared/watchdog.h
index 8c17e7e..5694338 100644 (file)
--- a/src/shared/watchdog.h
+++ b/src/shared/watchdog.h
@@ -25,6 +25,11 @@
 #include "time-util.h"
 #include "util.h"
 
+int watchdog_set_device(char *path);
 int watchdog_set_timeout(usec_t *usec);
 int watchdog_ping(void);
 void watchdog_close(bool disarm);
+
+static inline void watchdog_free_device(void) {
+        (void) watchdog_set_device(NULL);
+}