Keep the HPET-based hardlockup detector disabled unless explicitly enabled via a command line argument. If such parameter is not given, the hardlockup detector will fallback to use the perf-based implementation.
The function hardlockup_panic_setup() is updated to return 0 in order to to allow __setup functions of specific hardlockup detectors (in this case hardlockup_detector_hpet_setup()) to inspect the nmi_watchdog boot parameter. Cc: "H. Peter Anvin" <[email protected]> Cc: Ashok Raj <[email protected]> Cc: Andi Kleen <[email protected]> Cc: Tony Luck <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Clemens Ladisch <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: Philippe Ombredanne <[email protected]> Cc: Kate Stewart <[email protected]> Cc: "Rafael J. Wysocki" <[email protected]> Cc: Mimi Zohar <[email protected]> Cc: Jan Kiszka <[email protected]> Cc: Nick Desaulniers <[email protected]> Cc: Masahiro Yamada <[email protected]> Cc: Nayna Jain <[email protected]> Cc: "Ravi V. Shankar" <[email protected]> Cc: [email protected] Signed-off-by: Ricardo Neri <[email protected]> -- checkpatch gives the following warning: CHECK: __setup appears un-documented -- check Documentation/admin-guide/kernel-parameters.rst +__setup("nmi_watchdog=", hardlockup_detector_hpet_setup); This is a false-positive as the option nmi_watchdog is already documented. The option is re-evaluated in this file as well. --- .../admin-guide/kernel-parameters.txt | 6 +++++- arch/x86/kernel/watchdog_hld_hpet.c | 20 +++++++++++++++++++ kernel/watchdog.c | 2 +- 3 files changed, 26 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index cf8f5877d85f..c6270ddeb130 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2739,7 +2739,7 @@ Format: [state][,regs][,debounce][,die] nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels - Format: [panic,][nopanic,][num] + Format: [panic,][nopanic,][num,][hpet] Valid num: 0 or 1 0 - turn hardlockup detector in nmi_watchdog off 1 - turn hardlockup detector in nmi_watchdog on @@ -2749,6 +2749,10 @@ please see 'nowatchdog'. This is useful when you use a panic=... timeout and need the box quickly up again. + When hpet is specified, the NMI watchdog will be driven + by an HPET timer, if available in the system. Otherwise, + the perf-based implementation will be used. Specifying + hpet implies that nmi_watchdog is on. These settings can be accessed at runtime via the nmi_watchdog and hardlockup_panic sysctls. diff --git a/arch/x86/kernel/watchdog_hld_hpet.c b/arch/x86/kernel/watchdog_hld_hpet.c index 65b4699f249a..4402deff4b77 100644 --- a/arch/x86/kernel/watchdog_hld_hpet.c +++ b/arch/x86/kernel/watchdog_hld_hpet.c @@ -20,6 +20,7 @@ #include <asm/hpet.h> static struct hpet_hld_data *hld_data; +static bool hardlockup_use_hpet; /** * get_count() - Get the current count of the HPET timer @@ -391,6 +392,22 @@ void hardlockup_detector_hpet_stop(void) disable_timer(hld_data); } +/** + * hardlockup_detector_hpet_setup() - Parse command-line parameters + * @str: A string containing the kernel command line + * + * Parse the nmi_watchdog parameter from the kernel command line. If + * selected by the user, use this implementation to detect hardlockups. + */ +static int __init hardlockup_detector_hpet_setup(char *str) +{ + if (strstr(str, "hpet")) + hardlockup_use_hpet = true; + + return 0; +} +__setup("nmi_watchdog=", hardlockup_detector_hpet_setup); + /** * hardlockup_detector_hpet_init() - Initialize the hardlockup detector * @@ -405,6 +422,9 @@ int __init hardlockup_detector_hpet_init(void) { int ret; + if (!hardlockup_use_hpet) + return -ENODEV; + if (!is_hpet_enabled()) return -ENODEV; diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 367aa81294ef..28cad7310378 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -78,7 +78,7 @@ static int __init hardlockup_panic_setup(char *str) nmi_watchdog_user_enabled = 0; else if (!strncmp(str, "1", 1)) nmi_watchdog_user_enabled = 1; - return 1; + return 0; } __setup("nmi_watchdog=", hardlockup_panic_setup); -- 2.17.1
