Date: Fri, 27 Sep 2019 16:30:19 -0400 From: mike tancsa <mike@sentex.net> To: Warner Losh <imp@bsdimp.com> Cc: Aleksandr Rybalko <ray@ddteam.net>, freebsd-embedded <freebsd-embedded@freebsd.org> Subject: Re: watchdogd stat location Message-ID: <fcdd9659-d7e4-c554-b501-6b8cd178f6d7@sentex.net> In-Reply-To: <CANCZdfrRh7Ssf9vSSJ4Hopec1q7abLi9AdUqoPqZm4hPok6QUQ@mail.gmail.com> References: <5eba25eb-9ba4-0c93-27c8-e834491298ad@sentex.net> <CANCZdfp6bym5b6eFXFH0MxjYsAX%2B1Bi9fGXgp7sFM206zmsveQ@mail.gmail.com> <CAJ1Oi8FsG=nEBXdd0CS3U2zZSgh=SMcBO0ieY-KT5b1iDVFmJg@mail.gmail.com> <83831ae6-9275-4f0c-a23d-c9cca3dc28f4@sentex.net> <CANCZdfrRh7Ssf9vSSJ4Hopec1q7abLi9AdUqoPqZm4hPok6QUQ@mail.gmail.com>
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On 9/27/2019 3:53 PM, Warner Losh wrote:
> >
>
> I am all for that too. Just something other than /etc or /var
> which are
> often mounted on ramdisk.
>
>
> I think that / is too special to cause disk IO to ever happen. Other
> dirs will sometimes not be in the cache.... The notion here, perhaps
> bogus, is that we want to check the root FS is sane. The stat(2) is a
> cheap way to do this that will eventually fail if / goes wonky enough.
> It's weak.
>
>
Would something like this buy any extra sanity ? or not worth it. I
guess fancier checks belong in a passed program
# diff -u watchdogd.c.orig watchdogd.c
--- watchdogd.c.orig 2019-09-27 16:27:14.456973000 -0400
+++ watchdogd.c 2019-09-27 16:27:18.904885000 -0400
@@ -364,9 +364,23 @@
if (test_cmd != NULL)
failed = system(test_cmd);
- else
- failed = stat("/etc", &sb);
-
+ else {
+
+ srand(time(NULL));
+ switch(rand() % 4) {
+ case 0:
+ failed = stat("/", &sb);
+ break;
+ case 1:
+ failed = stat("/bin", &sb);
+ break;
+ case 2:
+ failed = stat("/sbin", &sb);
+ break;
+ default:
+ failed = stat("/usr", &sb);
+ }
+ }
error = watchdog_getuptime(&ts_end);
if (error) {
end_program = 1;
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