wdctl: use only sysfs if sufficient

Also avoid opening device if nowayout is set.

Opening the device node starts the watchdog.
With 'nowayout' enabled unstoppably.

Also the device node can only be opened once at the same time which can
be problematic.

Prefer to retrieve the information via sysfs which does not have such
problems.

Fixes #2543

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>

diff --git a/sys-utils/wdctl.c b/sys-utils/wdctl.c
index a5fdeaeb22412f596261028dfd3edf8c24faa73c..767f061fea226aa5e6f615c7e5f13f5bfb9f54c2 100644 (file)
--- a/sys-utils/wdctl.c
+++ b/sys-utils/wdctl.c
@@ -125,7 +125,12 @@ struct wd_device {
 
        struct watchdog_info ident;
 
-       unsigned int    has_timeout : 1,
+       unsigned int    has_identity : 1,
+                       has_fw_version : 1,
+                       has_options : 1,
+                       has_status : 1,
+                       has_bootstatus : 1,
+                       has_timeout : 1,
                        has_timeleft : 1,
                        has_pretimeout : 1,
                        has_nowayout : 1,
@@ -549,13 +554,16 @@ static int read_watchdog_from_sysfs(struct wd_device *wd)
        if (!sys)
                return 1;
 
-       ul_path_read_buffer(sys, (char *) wd->ident.identity, sizeof(wd->ident.identity), "identity");
-       ul_path_read_u32(sys, &wd->ident.firmware_version, "fw_version");
-       ul_path_scanf(sys, "options", "%x", &wd->ident.options);
-
-       ul_path_scanf(sys, "status", "%x", &wd->status);
-       ul_path_read_u32(sys, &wd->bstatus, "bootstatus");
-
+       if (ul_path_read_buffer(sys, (char *) wd->ident.identity, sizeof(wd->ident.identity), "identity") >= 0)
+               wd->has_identity = 1;
+       if (ul_path_read_u32(sys, &wd->ident.firmware_version, "fw_version") == 0)
+               wd->has_fw_version = 1;
+       if (ul_path_scanf(sys, "options", "%x", &wd->ident.options) == 1)
+               wd->has_options = 1;
+       if (ul_path_scanf(sys, "status", "%x", &wd->status) == 1)
+               wd->has_status = 1;
+       if (ul_path_read_u32(sys, &wd->bstatus, "bootstatus") == 0)
+               wd->has_bootstatus = 1;
        if (ul_path_read_s32(sys, &wd->nowayout, "nowayout") == 0)
                wd->has_nowayout = 1;
        if (ul_path_read_s32(sys, &wd->timeout, "timeout") == 0)
@@ -598,12 +606,32 @@ static int read_governors(struct wd_device *wd)
        return 0;
 }
 
+static bool should_read_from_device(struct wd_device *wd)
+{
+       if (!wd->has_nowayout)
+               return false;
+
+       if (wd->nowayout)
+               return false;
+
+       return !wd->has_identity ||
+              !wd->has_fw_version ||
+              !wd->has_options ||
+              !wd->has_status ||
+              !wd->has_bootstatus ||
+              !wd->has_timeout ||
+              !wd->has_timeleft;
+              // pretimeout attribute may be hidden in sysfs
+}
+
 static int read_watchdog(struct wd_device *wd)
 {
-       int rc = read_watchdog_from_device(wd);
+       int rc;
+
+       rc = read_watchdog_from_sysfs(wd);
 
-       if (rc == -EBUSY || rc == -EACCES || rc == -EPERM)
-               rc = read_watchdog_from_sysfs(wd);
+       if (rc && should_read_from_device(wd))
+               rc = read_watchdog_from_device(wd);
 
        if (rc) {
                warn(_("cannot read information about %s"), wd->devpath);