From: Masami Hiramatsu (Google) <[email protected]> Add register_wide_hw_breakpoint_cpuslocked() which registers a wide hardware breakpoint across all online CPUs while caller holds cpus_read_lock(). This allows callers who need to perform additional setup under cpus_read_lock() without releasing it to avoid races with CPU hotplug and without triggering recursive lockdep warnings.
Refactor register_wide_hw_breakpoint() as a wrapper around register_wide_hw_breakpoint_cpuslocked(). Assisted-by: LLM Signed-off-by: Masami Hiramatsu (Google) <[email protected]> --- include/linux/hw_breakpoint.h | 9 +++++++++ kernel/events/hw_breakpoint.c | 38 ++++++++++++++++++++++++++++++++------ 2 files changed, 41 insertions(+), 6 deletions(-) diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h index bf65c7fffd99..65efe55fef14 100644 --- a/include/linux/hw_breakpoint.h +++ b/include/linux/hw_breakpoint.h @@ -76,6 +76,11 @@ register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr, void *context, int cpu); +extern struct perf_event * __percpu * +register_wide_hw_breakpoint_cpuslocked(struct perf_event_attr *attr, + perf_overflow_handler_t triggered, + void *context); + extern struct perf_event * __percpu * register_wide_hw_breakpoint(struct perf_event_attr *attr, perf_overflow_handler_t triggered, @@ -123,6 +128,10 @@ register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr, void *context, int cpu) { return NULL; } static inline struct perf_event * __percpu * +register_wide_hw_breakpoint_cpuslocked(struct perf_event_attr *attr, + perf_overflow_handler_t triggered, + void *context) { return NULL; } +static inline struct perf_event * __percpu * register_wide_hw_breakpoint(struct perf_event_attr *attr, perf_overflow_handler_t triggered, void *context) { return NULL; } diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index 69bfb17b87c4..5627ad97600a 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -832,27 +832,30 @@ void unregister_hw_breakpoint(struct perf_event *bp) EXPORT_SYMBOL_GPL(unregister_hw_breakpoint); /** - * register_wide_hw_breakpoint - register a wide breakpoint in the kernel + * register_wide_hw_breakpoint_cpuslocked - register a wide breakpoint with cpus locked * @attr: breakpoint attributes * @triggered: callback to trigger when we hit the breakpoint * @context: context data could be used in the triggered callback * + * Same as register_wide_hw_breakpoint(), but caller must hold cpus_read_lock(). + * * @return a set of per_cpu pointers to perf events */ struct perf_event * __percpu * -register_wide_hw_breakpoint(struct perf_event_attr *attr, - perf_overflow_handler_t triggered, - void *context) +register_wide_hw_breakpoint_cpuslocked(struct perf_event_attr *attr, + perf_overflow_handler_t triggered, + void *context) { struct perf_event * __percpu *cpu_events, *bp; long err = 0; int cpu; + lockdep_assert_cpus_held(); + cpu_events = alloc_percpu(typeof(*cpu_events)); if (!cpu_events) return ERR_PTR_PCPU(-ENOMEM); - cpus_read_lock(); for_each_online_cpu(cpu) { bp = perf_event_create_kernel_counter(attr, cpu, NULL, triggered, context); @@ -863,7 +866,6 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, per_cpu(*cpu_events, cpu) = bp; } - cpus_read_unlock(); if (likely(!err)) return cpu_events; @@ -871,6 +873,30 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, unregister_wide_hw_breakpoint(cpu_events); return ERR_PTR_PCPU(err); } +EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint_cpuslocked); + +/** + * register_wide_hw_breakpoint - register a wide breakpoint in the kernel + * @attr: breakpoint attributes + * @triggered: callback to trigger when we hit the breakpoint + * @context: context data could be used in the triggered callback + * + * @return a set of per_cpu pointers to perf events + */ +struct perf_event * __percpu * +register_wide_hw_breakpoint(struct perf_event_attr *attr, + perf_overflow_handler_t triggered, + void *context) +{ + struct perf_event * __percpu *cpu_events; + + cpus_read_lock(); + cpu_events = register_wide_hw_breakpoint_cpuslocked(attr, triggered, + context); + cpus_read_unlock(); + + return cpu_events; +} EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint); /**
