[PATCH v19 01/13] arm64: Add cpus_are_stuck_in_kernel
From: geoff@infradead.org (Geoff Levand)
Date: 2016-06-16 23:48:27
Also in:
kexec
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
From: James Morse <james.morse@arm.com> kernel/smp.c has a fancy counter that keeps track of the number of CPUs it marked as not-present and left in cpu_park_loop(). If there are any CPUs spinning in here, kexec will release them once the memory is re-used by the new kernel. Provide a function to expose whether this counter is non-zero, so we can use this when loading a new kexec image, and when calling machine_kexec(). Signed-off-by: James Morse <james.morse@arm.com> [Split off from a larger patch] Signed-off-by: Geoff Levand <geoff@infradead.org> --- arch/arm64/include/asm/smp.h | 10 ++++++++++ arch/arm64/kernel/smp.c | 5 +++++ 2 files changed, 15 insertions(+)
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index 433e504..38712f4 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h@@ -124,6 +124,16 @@ static inline void cpu_panic_kernel(void) cpu_park_loop(); } +/* + * If a secondary CPU fails to come online, (e.g. due to mismatched features), + * it will try to call cpu_die(). If this fails, it updates + * cpus_stuck_in_kernel and sits in cpu_park_loop(). + * + * Kexec checks this counter and refuses to load/kexec if it is non-zero, as + * cpu_park_loop() would be overwritten releasing the parked cpus. + */ +bool cpus_are_stuck_in_kernel(void); + #endif /* ifndef __ASSEMBLY__ */ #endif /* ifndef __ASM_SMP_H */
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 678e084..d0bcd55 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c@@ -909,3 +909,8 @@ int setup_profiling_timer(unsigned int multiplier) { return -EINVAL; } + +bool cpus_are_stuck_in_kernel(void) +{ + return !!cpus_stuck_in_kernel; +}
--
2.5.0