Add a blocking notifier chain to allow subsystems to be notified before kexec execution. This enables modules to perform necessary cleanup or validation before the system transitions to a new kernel or block kexec if not possible under current conditions.
Signed-off-by: Stanislav Kinsburskii <[email protected]> --- include/linux/kexec.h | 6 ++++++ kernel/kexec_core.c | 24 ++++++++++++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/include/linux/kexec.h b/include/linux/kexec.h index ff7e231b0485..311037d30f9e 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -35,6 +35,7 @@ extern note_buf_t __percpu *crash_notes; #include <linux/ioport.h> #include <linux/module.h> #include <linux/highmem.h> +#include <linux/notifier.h> #include <asm/kexec.h> #include <linux/crash_core.h> @@ -532,10 +533,13 @@ extern bool kexec_file_dbg_print; extern void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size); extern void kimage_unmap_segment(void *buffer); +extern int kexec_block_notifier_register(struct notifier_block *nb); +extern int kexec_block_notifier_unregister(struct notifier_block *nb); #else /* !CONFIG_KEXEC_CORE */ struct pt_regs; struct task_struct; struct kimage; +struct notifier_block; static inline void __crash_kexec(struct pt_regs *regs) { } static inline void crash_kexec(struct pt_regs *regs) { } static inline int kexec_should_crash(struct task_struct *p) { return 0; } @@ -543,6 +547,8 @@ static inline int kexec_crash_loaded(void) { return 0; } static inline void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size) { return NULL; } static inline void kimage_unmap_segment(void *buffer) { } +static inline int kexec_block_notifier_register(struct notifier_block *nb) { } +static inline int kexec_block_notifier_unregister(struct notifier_block *nb) { } #define kexec_in_progress false #endif /* CONFIG_KEXEC_CORE */ diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 0f92acdd354d..1e86a6f175f0 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -57,6 +57,20 @@ bool kexec_in_progress = false; bool kexec_file_dbg_print; +static BLOCKING_NOTIFIER_HEAD(kexec_block_list); + +int kexec_block_notifier_register(struct notifier_block *nb) +{ + return blocking_notifier_chain_register(&kexec_block_list, nb); +} +EXPORT_SYMBOL_GPL(kexec_block_notifier_register); + +int kexec_block_notifier_unregister(struct notifier_block *nb) +{ + return blocking_notifier_chain_unregister(&kexec_block_list, nb); +} +EXPORT_SYMBOL_GPL(kexec_block_notifier_unregister); + /* * When kexec transitions to the new kernel there is a one-to-one * mapping between physical and virtual addresses. On processors @@ -1124,6 +1138,12 @@ bool kexec_load_permitted(int kexec_image_type) return true; } +static int kexec_check_blockers(void) +{ + /* Notify subsystems of impending kexec */ + return blocking_notifier_call_chain(&kexec_block_list, 0, NULL); +} + /* * Move into place and start executing a preloaded standalone * executable. If nothing was preloaded return an error. @@ -1139,6 +1159,10 @@ int kernel_kexec(void) goto Unlock; } + error = kexec_check_blockers(); + if (error) + goto Unlock; + error = liveupdate_reboot(); if (error) goto Unlock;
