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Miller" , linux-perf-users@vger.kernel.org, Douglas Anderson Subject: [PATCH 01/10] watchdog/hardlockup: Keep kernel.nmi_watchdog sysctl as 0444 if probe fails Date: Fri, 26 May 2023 18:41:31 -0700 Message-ID: <20230526184139.1.I0d75971cc52a7283f495aac0bd5c3041aadc734e@changeid> X-Mailer: git-send-email 2.41.0.rc0.172.g3f132b7071-goog In-Reply-To: <20230527014153.2793931-1-dianders@chromium.org> References: <20230527014153.2793931-1-dianders@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The permissions for the kernel.nmi_watchdog sysctl have always been set at compile time despite the fact that a watchdog can fail to probe. Let's fix this and set the permissions based on whether the hardlockup detector actually probed. Fixes: a994a3147e4c ("watchdog/hardlockup/perf: Implement init time detecti= on of perf") Reported-by: Petr Mladek Closes: https://lore.kernel.org/r/ZHCn4hNxFpY5-9Ki@alley Signed-off-by: Douglas Anderson Reviewed-by: Petr Mladek --- include/linux/nmi.h | 6 ------ kernel/watchdog.c | 30 ++++++++++++++++++++---------- 2 files changed, 20 insertions(+), 16 deletions(-) diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 333465e235e1..3a27169ec383 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -95,12 +95,6 @@ void watchdog_hardlockup_check(unsigned int cpu, struct = pt_regs *regs); static inline void arch_touch_nmi_watchdog(void) { } #endif =20 -#if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTO= R) -# define NMI_WATCHDOG_SYSCTL_PERM 0644 -#else -# define NMI_WATCHDOG_SYSCTL_PERM 0444 -#endif - #if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF) extern void hardlockup_detector_perf_stop(void); extern void hardlockup_detector_perf_restart(void); diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 237990e8d345..4b9e31edb47f 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -880,15 +880,6 @@ static struct ctl_table watchdog_sysctls[] =3D { .extra1 =3D SYSCTL_ZERO, .extra2 =3D (void *)&sixty, }, - { - .procname =3D "nmi_watchdog", - .data =3D &watchdog_hardlockup_user_enabled, - .maxlen =3D sizeof(int), - .mode =3D NMI_WATCHDOG_SYSCTL_PERM, - .proc_handler =3D proc_nmi_watchdog, - .extra1 =3D SYSCTL_ZERO, - .extra2 =3D SYSCTL_ONE, - }, { .procname =3D "watchdog_cpumask", .data =3D &watchdog_cpumask_bits, @@ -952,10 +943,28 @@ static struct ctl_table watchdog_sysctls[] =3D { {} }; =20 +static struct ctl_table watchdog_hardlockup_sysctl[] =3D { + { + .procname =3D "nmi_watchdog", + .data =3D &watchdog_hardlockup_user_enabled, + .maxlen =3D sizeof(int), + .mode =3D 0444, + .proc_handler =3D proc_nmi_watchdog, + .extra1 =3D SYSCTL_ZERO, + .extra2 =3D SYSCTL_ONE, + }, + {} +}; + static void __init watchdog_sysctl_init(void) { register_sysctl_init("kernel", watchdog_sysctls); + + if (watchdog_hardlockup_available) + watchdog_hardlockup_sysctl[0].mode =3D 0644; + register_sysctl_init("kernel", watchdog_hardlockup_sysctl); } + #else #define watchdog_sysctl_init() do { } while (0) #endif /* CONFIG_SYSCTL */ @@ -1011,6 +1020,8 @@ static int __init lockup_detector_check(void) /* Make sure no work is pending. */ flush_work(&detector_work); =20 + watchdog_sysctl_init(); + return 0; =20 } @@ -1030,5 +1041,4 @@ void __init lockup_detector_init(void) allow_lockup_detector_init_retry =3D true; =20 lockup_detector_setup(); - watchdog_sysctl_init(); } --=20 2.41.0.rc0.172.g3f132b7071-goog