diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 1afe9623c1a7268cd2ef8949a248ef79216fe2e9..a3c19034d5f8de83f52f1ae7fb1410b088c6fc70 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -401,6 +401,7 @@ struct perf_event_attr { #define PERF_EVENT_IOC_SET_FILTER _IOW('$', 6, char *) #define PERF_EVENT_IOC_ID _IOR('$', 7, __u64 *) #define PERF_EVENT_IOC_SET_BPF _IOW('$', 8, __u32) +#define PERF_EVENT_IOC_PAUSE_OUTPUT _IOW('$', 9, __u32) enum perf_event_ioc_flags { PERF_IOC_FLAG_GROUP = 1U << 0, diff --git a/kernel/events/core.c b/kernel/events/core.c index 243df4b62870156fec83602e7c960c087a3916d0..51386e84293e3bfb145c3fe5dd641aa4d6235613 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4379,6 +4379,19 @@ static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned lon case PERF_EVENT_IOC_SET_BPF: return perf_event_set_bpf_prog(event, arg); + case PERF_EVENT_IOC_PAUSE_OUTPUT: { + struct ring_buffer *rb; + + rcu_read_lock(); + rb = rcu_dereference(event->rb); + if (!rb || !rb->nr_pages) { + rcu_read_unlock(); + return -EINVAL; + } + rb_toggle_paused(rb, !!arg); + rcu_read_unlock(); + return 0; + } default: return -ENOTTY; } diff --git a/kernel/events/internal.h b/kernel/events/internal.h index 2b229fdcfc099f608c601e83b43c2fcdb1eba12b..2d67327d9ad98167931e0876cca38a08b2ea23b2 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -17,6 +17,7 @@ struct ring_buffer { #endif int nr_pages; /* nr of data pages */ int overwrite; /* can overwrite itself */ + int paused; /* can write into ring buffer */ atomic_t poll; /* POLL_ for wakeups */ @@ -64,6 +65,14 @@ static inline void rb_free_rcu(struct rcu_head *rcu_head) rb_free(rb); } +static inline void rb_toggle_paused(struct ring_buffer *rb, bool pause) +{ + if (!pause && rb->nr_pages) + rb->paused = 0; + else + rb->paused = 1; +} + extern struct ring_buffer * rb_alloc(int nr_pages, long watermark, int cpu, int flags); extern void perf_event_wakeup(struct perf_event *event); diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 0ed4555309bd31612104f5d459cc6dd0249c524b..72d8127bb8fde9588e3fd0281c168ae03e580e75 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -125,8 +125,11 @@ int perf_output_begin(struct perf_output_handle *handle, if (unlikely(!rb)) goto out; - if (unlikely(!rb->nr_pages)) + if (unlikely(rb->paused)) { + if (rb->nr_pages) + local_inc(&rb->lost); goto out; + } handle->rb = rb; handle->event = event; @@ -241,6 +244,13 @@ ring_buffer_init(struct ring_buffer *rb, long watermark, int flags) INIT_LIST_HEAD(&rb->event_list); spin_lock_init(&rb->event_lock); + + /* + * perf_output_begin() only checks rb->paused, therefore + * rb->paused must be true if we have no pages for output. + */ + if (!rb->nr_pages) + rb->paused = 1; } /*