Mailing List Archive

"watchdog_timeout=0" is documented to disable the watchdog, which wasn't
really the case; the watchdog was rather ran with an, in practice,
infinite timeout. Fold that command line option with "watchdog",
resetting to defaults whenever encountering a new instance.

While touching opt_watchdog_timeout, also move it into .data.ro_after_init.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
Really I think the comment in watchdog_setup() is wrong, and the
function would hence better go away. The CPU notifier registration can
surely be done in a pre-SMP initcall, which would have the benefit of
boot-time AP bringup then working the same as runtime CPU-onlining. (In
particular the set_timer() out of CPU_UP_PREPARE is a little suspicious,
as the timer can't possibly be run right away when a CPU isn't online
yet.) Which would leave __start_xen() to call watchdog_enable() in the
place it's calling watchdog_setup() now.
---
v2: Re-do largely from scratch.

--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,8 @@ The format is based on [.Keep a Changelog
- On x86:
- HVM PIRQs are disabled by default.
- Reduce IOMMU setup time for hardware domain.
+ - The "watchdog_timeout=" command line option is subsumed by the "watchdog="
+ one.

### Added
- On x86:
--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -2790,22 +2790,19 @@ suboptimal scheduling decisions, but onl
oversubscribed (i.e., in total there are more vCPUs than pCPUs).

### watchdog (x86)
-> `= force | <boolean>`
+> `= <boolean> | List of [ force | <integer>s ]`

> Default: `false`

Run an NMI watchdog on each processor. If a processor is stuck for
-longer than the **watchdog_timeout**, a panic occurs. When `force` is
-specified, in addition to running an NMI watchdog on each processor,
-unknown NMIs will still be processed.
+longer than the specified or default timeout, a panic occurs.

-### watchdog_timeout (x86)
-> `= <integer>`
+* When `force` is specified, in addition to running an NMI watchdog on each
+ processor, unknown NMIs will still be processed.

-> Default: `5`
-
-Set the NMI watchdog timeout in seconds. Specifying `0` will turn off
-the watchdog.
+* The <integer>s value allows to set the NMI watchdog timeout in seconds
+ (default: `5s`). Specifying `0` will turn off the watchdog. Specifying
+ a non-zero value enables the watchdog.

### x2apic (x86)
> `= <boolean>`
--- a/xen/arch/x86/nmi.c
+++ b/xen/arch/x86/nmi.c
@@ -48,8 +48,20 @@ bool __initdata opt_watchdog;
/* watchdog_force: If true, process unknown NMIs when running the watchdog. */
bool watchdog_force;

+#define WATCHDOG_TIMEOUT_DEFAULT 5 /* seconds */
+
+/* opt_watchdog_timeout: Number of seconds to wait before panic. */
+static unsigned int __ro_after_init opt_watchdog_timeout = WATCHDOG_TIMEOUT_DEFAULT;
+
static int __init cf_check parse_watchdog(const char *s)
{
+ const char *ss;
+ int rc = 0;
+
+ /* Reset to defaults. */
+ watchdog_force = false;
+ opt_watchdog_timeout = WATCHDOG_TIMEOUT_DEFAULT;
+
if ( !*s )
{
opt_watchdog = true;
@@ -66,28 +78,42 @@ static int __init cf_check parse_watchdo
return 0;
}

- if ( !strcmp(s, "force") )
- watchdog_force = opt_watchdog = true;
- else
- return -EINVAL;
+ do {
+ ss = strchr(s, ',');
+ if ( !ss )
+ ss = strchr(s, '\0');
+
+ if ( !cmdline_strcmp(s, "force") )
+ {
+ watchdog_force = opt_watchdog = true;
+
+ if ( !opt_watchdog_timeout )
+ opt_watchdog_timeout = WATCHDOG_TIMEOUT_DEFAULT;
+ }
+ else if ( isdigit(*s) )
+ {
+ unsigned long value = simple_strtoul(s, &s, 0);
+
+ if ( *s == 's' && s + 1 == ss )
+ {
+ opt_watchdog_timeout = value;
+ if ( opt_watchdog_timeout != value )
+ opt_watchdog_timeout = WATCHDOG_TIMEOUT_DEFAULT;
+
+ opt_watchdog = !!opt_watchdog_timeout;
+ }
+ else
+ rc = -EINVAL;
+ }
+ else
+ rc = -EINVAL;

- return 0;
-}
-custom_param("watchdog", parse_watchdog);
+ s = ss + 1;
+ } while ( *ss );

-/* opt_watchdog_timeout: Number of seconds to wait before panic. */
-static unsigned int opt_watchdog_timeout = 5;
-
-static int __init cf_check parse_watchdog_timeout(const char *s)
-{
- const char *q;
-
- opt_watchdog_timeout = simple_strtoull(s, &q, 0);
- opt_watchdog = !!opt_watchdog_timeout;
-
- return *q ? -EINVAL : 0;
+ return rc;
}
-custom_param("watchdog_timeout", parse_watchdog_timeout);
+custom_param("watchdog", parse_watchdog);

/*
* lapic_nmi_owner tracks the ownership of the lapic NMI hardware: