diff options
| -rw-r--r-- | include/linux/ring_buffer.h | 1 | ||||
| -rw-r--r-- | kernel/trace/ring_buffer.c | 21 | ||||
| -rw-r--r-- | kernel/trace/trace.c | 13 |
3 files changed, 35 insertions, 0 deletions
diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 876358cfe1b1..d862fa610270 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -248,6 +248,7 @@ int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node); int ring_buffer_map(struct trace_buffer *buffer, int cpu, struct vm_area_struct *vma); +void ring_buffer_map_dup(struct trace_buffer *buffer, int cpu); int ring_buffer_unmap(struct trace_buffer *buffer, int cpu); int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu); #endif /* _LINUX_RING_BUFFER_H */ diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index f16f053ef77d..17d0ea0cc3e6 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7310,6 +7310,27 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu, return err; } +/* + * This is called when a VMA is duplicated (e.g., on fork()) to increment + * the user_mapped counter without remapping pages. + */ +void ring_buffer_map_dup(struct trace_buffer *buffer, int cpu) +{ + struct ring_buffer_per_cpu *cpu_buffer; + + if (WARN_ON(!cpumask_test_cpu(cpu, buffer->cpumask))) + return; + + cpu_buffer = buffer->buffers[cpu]; + + guard(mutex)(&cpu_buffer->mapping_lock); + + if (cpu_buffer->user_mapped) + __rb_inc_dec_mapped(cpu_buffer, true); + else + WARN(1, "Unexpected buffer stat, it should be mapped"); +} + int ring_buffer_unmap(struct trace_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 23de3719f495..1e7c032a72d2 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8213,6 +8213,18 @@ static inline int get_snapshot_map(struct trace_array *tr) { return 0; } static inline void put_snapshot_map(struct trace_array *tr) { } #endif +/* + * This is called when a VMA is duplicated (e.g., on fork()) to increment + * the user_mapped counter without remapping pages. + */ +static void tracing_buffers_mmap_open(struct vm_area_struct *vma) +{ + struct ftrace_buffer_info *info = vma->vm_file->private_data; + struct trace_iterator *iter = &info->iter; + + ring_buffer_map_dup(iter->array_buffer->buffer, iter->cpu_file); +} + static void tracing_buffers_mmap_close(struct vm_area_struct *vma) { struct ftrace_buffer_info *info = vma->vm_file->private_data; @@ -8232,6 +8244,7 @@ static int tracing_buffers_may_split(struct vm_area_struct *vma, unsigned long a } static const struct vm_operations_struct tracing_buffers_vmops = { + .open = tracing_buffers_mmap_open, .close = tracing_buffers_mmap_close, .may_split = tracing_buffers_may_split, }; |