[PATCH v3 02/15] smp: Create a new function to shutdown nonboot cpus
From: Qais Yousef <hidden>
Date: 2020-02-23 19:30:00
Also in:
lkml
Subsystem:
cpu hotplug, the rest · Maintainers:
Thomas Gleixner, Peter Zijlstra, Linus Torvalds
This function will be used later in machine_shutdown() for some archs. disable_nonboot_cpus() is not safe to use when doing machine_down(), because it relies on freeze_secondary_cpus() which in turn is a suspend/resume related freeze and could abort if the logic detects any pending activities that can prevent finishing the offlining process. Signed-off-by: Qais Yousef <redacted> CC: Thomas Gleixner <redacted> CC: Josh Poimboeuf <redacted> CC: "Peter Zijlstra (Intel)" <peterz@infradead.org> CC: Jiri Kosina <redacted> CC: Nicholas Piggin <npiggin@gmail.com> CC: Daniel Lezcano <redacted> CC: Ingo Molnar <mingo@kernel.org> CC: Eiichi Tsukata <redacted> CC: Zhenzhong Duan <redacted> CC: Nadav Amit <redacted> CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org> CC: "Rafael J. Wysocki" <redacted> CC: Tony Luck <tony.luck@intel.com> CC: Fenghua Yu <redacted> CC: Russell King <linux@armlinux.org.uk> CC: Catalin Marinas <catalin.marinas@arm.com> CC: Will Deacon <will@kernel.org> CC: linux-arm-kernel@lists.infradead.org CC: linux-ia64@vger.kernel.org CC: linux-kernel@vger.kernel.org --- include/linux/cpu.h | 2 ++ kernel/cpu.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 44 insertions(+)
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index cf8cf38dca43..64a246e9c8db 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h@@ -120,6 +120,7 @@ extern void cpu_hotplug_enable(void); void clear_tasks_mm_cpumask(int cpu); int cpu_down(unsigned int cpu); int remove_cpu(unsigned int cpu); +extern void smp_shutdown_nonboot_cpus(unsigned int primary_cpu); #else /* CONFIG_HOTPLUG_CPU */
@@ -131,6 +132,7 @@ static inline int cpus_read_trylock(void) { return true; } static inline void lockdep_assert_cpus_held(void) { } static inline void cpu_hotplug_disable(void) { } static inline void cpu_hotplug_enable(void) { } +static inline void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) { } #endif /* !CONFIG_HOTPLUG_CPU */ /* Wrappers which go away once all code is converted */
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 069802f7010f..03c727195b65 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c@@ -1069,6 +1069,48 @@ int remove_cpu(unsigned int cpu) } EXPORT_SYMBOL_GPL(remove_cpu); +void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) +{ + unsigned int cpu; + int error; + + cpu_maps_update_begin(); + + /* + * Make certain the cpu I'm about to reboot on is online. + * + * This is inline to what migrate_to_reboot_cpu() already do. + */ + if (!cpu_online(primary_cpu)) + primary_cpu = cpumask_first(cpu_online_mask); + + for_each_online_cpu(cpu) { + if (cpu == primary_cpu) + continue; + + error = cpu_down_maps_locked(cpu, CPUHP_OFFLINE); + if (error) { + pr_err("Failed to offline CPU%d - error=%d", + cpu, error); + break; + } + } + + /* + * Ensure all but the reboot CPU are offline. + */ + BUG_ON(num_online_cpus() > 1); + + /* + * Make sure the CPUs won't be enabled by someone else after this + * point. Kexec will reboot to a new kernel shortly resetting + * everything along the way. + */ + cpu_hotplug_disabled++; + + cpu_maps_update_done(); +} + #else #define takedown_cpu NULL #endif /*CONFIG_HOTPLUG_CPU*/
--
2.17.1
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