diff options
Diffstat (limited to 'include/linux/bpf.h')
| -rw-r--r-- | include/linux/bpf.h | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 76b3a0eb1502..1acd5bf70350 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -961,6 +961,36 @@ _out: \ #ifdef CONFIG_BPF_SYSCALL DECLARE_PER_CPU(int, bpf_prog_active); +/* + * Block execution of BPF programs attached to instrumentation (perf, + * kprobes, tracepoints) to prevent deadlocks on map operations as any of + * these events can happen inside a region which holds a map bucket lock + * and can deadlock on it. + * + * Use the preemption safe inc/dec variants on RT because migrate disable + * is preemptible on RT and preemption in the middle of the RMW operation + * might lead to inconsistent state. Use the raw variants for non RT + * kernels as migrate_disable() maps to preempt_disable() so the slightly + * more expensive save operation can be avoided. + */ +static inline void bpf_disable_instrumentation(void) +{ + migrate_disable(); + if (IS_ENABLED(CONFIG_PREEMPT_RT)) + this_cpu_inc(bpf_prog_active); + else + __this_cpu_inc(bpf_prog_active); +} + +static inline void bpf_enable_instrumentation(void) +{ + if (IS_ENABLED(CONFIG_PREEMPT_RT)) + this_cpu_dec(bpf_prog_active); + else + __this_cpu_dec(bpf_prog_active); + migrate_enable(); +} + extern const struct file_operations bpf_map_fops; extern const struct file_operations bpf_prog_fops; |