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-rw-r--r--tools/lib/bpf/libbpf.c10
1 files changed, 4 insertions, 6 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index bd71efcc53be..0c21355f04a7 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -27,6 +27,7 @@
#include <linux/list.h>
#include <linux/limits.h>
#include <linux/perf_event.h>
+#include <linux/ring_buffer.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/vfs.h>
@@ -2418,13 +2419,12 @@ bpf_perf_event_read_simple(void *mem, unsigned long size,
unsigned long page_size, void **buf, size_t *buf_len,
bpf_perf_event_print_t fn, void *priv)
{
- volatile struct perf_event_mmap_page *header = mem;
+ struct perf_event_mmap_page *header = mem;
+ __u64 data_head = ring_buffer_read_head(header);
__u64 data_tail = header->data_tail;
- __u64 data_head = header->data_head;
int ret = LIBBPF_PERF_EVENT_ERROR;
void *base, *begin, *end;
- asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */
if (data_head == data_tail)
return LIBBPF_PERF_EVENT_CONT;
@@ -2467,8 +2467,6 @@ bpf_perf_event_read_simple(void *mem, unsigned long size,
data_tail += ehdr->size;
}
- __sync_synchronize(); /* smp_mb() */
- header->data_tail = data_tail;
-
+ ring_buffer_write_tail(header, data_tail);
return ret;
}