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Date: Wed, 25 Jun 2014 20:44:34 +0200
From: Jiri Olsa <jolsa@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Ingo Molnar <mingo@...nel.org>,
Paul Mackerras <paulus@...ba.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Jiri Olsa <jolsa@...nel.org>
Subject: [PATCH 0/1] perf: Fix race in sample output
hi,
the perf test patch below is not to be merged. It's
just to show how to hit issue fixed by patch 1/1.
thanks,
jirka
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
tools/perf/Makefile.perf | 1 +
tools/perf/tests/builtin-test.c | 4 +
tools/perf/tests/group-read-bug.c | 169 ++++++++++++++++++++++++++++++++++++++
tools/perf/tests/tests.h | 1 +
4 files changed, 175 insertions(+)
create mode 100644 tools/perf/tests/group-read-bug.c
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 9670a16..909084f 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -419,6 +419,7 @@ endif
endif
LIB_OBJS += $(OUTPUT)tests/mmap-thread-lookup.o
LIB_OBJS += $(OUTPUT)tests/thread-mg-share.o
+LIB_OBJS += $(OUTPUT)tests/group-read-bug.o
BUILTIN_OBJS += $(OUTPUT)builtin-annotate.o
BUILTIN_OBJS += $(OUTPUT)builtin-bench.o
diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 6f8b01b..2b2d544 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -154,6 +154,10 @@ static struct test {
.func = test__hists_cumulate,
},
{
+ .desc = "Test group read bug",
+ .func = test__group_read_bug,
+ },
+ {
.func = NULL,
},
};
diff --git a/tools/perf/tests/group-read-bug.c b/tools/perf/tests/group-read-bug.c
new file mode 100644
index 0000000..d69fabf
--- /dev/null
+++ b/tools/perf/tests/group-read-bug.c
@@ -0,0 +1,169 @@
+#include <unistd.h>
+#include <sys/syscall.h> /* For SYS_xxx definitions */
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <signal.h>
+#include <pthread.h>
+#include "tests.h"
+#include "perf.h"
+#include "debug.h"
+#include "trace-event.h"
+
+static int fd_leader;
+static bool done;
+static int pid;
+
+static int create_event(int group_fd)
+{
+ struct perf_event_attr pe;
+ struct event_format* format;
+ int fd;
+
+ memset(&pe, 0, sizeof(struct perf_event_attr));
+ pe.type = PERF_TYPE_TRACEPOINT;
+ pe.size = sizeof(struct perf_event_attr);
+
+ format = trace_event__tp_format("syscalls", "sys_enter_read");
+ if (!format)
+ return TEST_FAIL;
+
+ pe.config = format->id;
+ pe.sample_period = 1;
+ pe.sample_type = PERF_SAMPLE_ID|PERF_SAMPLE_READ;
+ pe.read_format = PERF_FORMAT_ID|PERF_FORMAT_GROUP;
+
+ if (group_fd == -1)
+ pe.disabled = 1;
+
+ fd = sys_perf_event_open(&pe, pid, -1, group_fd, 0);
+ if (fd < 0) {
+ pr_debug("failed opening event %llx, errno %d\n",
+ pe.config, errno);
+ return TEST_FAIL;
+ }
+
+ return fd;
+}
+
+static __u64 read_head(struct perf_event_mmap_page *pc)
+{
+ __u64 head = ACCESS_ONCE(pc->data_head);
+ rmb();
+ return head;
+}
+
+static void write_tail(struct perf_event_mmap_page *pc, __u64 tail)
+{
+ mb();
+ pc->data_tail = tail;
+}
+
+static void mmap_read(struct perf_event_mmap_page *pc, int mask)
+{
+ __u64 old = 0;
+ __u64 empty = 0;
+
+ while (!done) {
+ __u64 size, head;
+
+ head = read_head(pc);
+
+ if (old == head) {
+ empty++;
+ continue;
+ }
+
+ size = head - old;
+
+ pr_debug("empty %llu, head = %llu, size %llu\n", empty, head, size);
+ empty = 0;
+
+ if ((old & mask) + size != (head & mask)) {
+ size = mask + 1 - (old & mask);
+ old += size;
+ }
+
+ size = head - old;
+ old += size;
+ write_tail(pc, old);
+ }
+}
+
+static void *worker_thread(void *data __maybe_unused)
+{
+#define CNT 1000
+ int fds[CNT];
+
+ while (!done) {
+ int i;
+
+ for (i = 0; i < CNT; i++)
+ fds[i] = create_event(fd_leader);
+
+ for (i = 0; i < CNT; i++)
+ close(fds[i]);
+ }
+
+ return NULL;
+}
+
+static void *gen_thread(void *data __maybe_unused)
+{
+ pid = syscall(SYS_gettid);
+
+ while (!done) {
+ int i;
+
+ i = read(300, &i, sizeof(i));
+ }
+
+ return NULL;
+}
+
+static void signal_fn(int signo __maybe_unused)
+{
+ done = 1;
+}
+
+int test__group_read_bug(void)
+{
+ pthread_t pthread, pthread_gen;
+ int mmap_len = page_size + (page_size << 5);
+ int mmap_mask = mmap_len - page_size - 1;
+ void *buf;
+ int err;
+
+ signal(SIGINT, signal_fn);
+
+ err = pthread_create(&pthread, NULL, gen_thread, NULL);
+ TEST_ASSERT_VAL("create gen", !err);
+
+ while(!pid) {
+ pr_debug("waiting for pid\n");
+ sleep(1);
+ }
+
+ fd_leader = create_event(-1);
+ TEST_ASSERT_VAL("create a leader", fd_leader >= 0);
+
+ buf = mmap(NULL, mmap_len, PROT_READ|PROT_WRITE, MAP_SHARED, fd_leader, 0);
+ TEST_ASSERT_VAL("mmap leader", buf != MAP_FAILED);
+
+ err = ioctl(fd_leader, PERF_EVENT_IOC_ENABLE, 0);
+ TEST_ASSERT_VAL("enable leader", !err);
+
+ err = pthread_create(&pthread_gen, NULL, worker_thread, NULL);
+ TEST_ASSERT_VAL("create worker", !err);
+
+ mmap_read(buf, mmap_mask);
+
+ munmap(buf, mmap_len);
+ close(fd_leader);
+
+ pthread_join(pthread, NULL);
+ pthread_join(pthread_gen, NULL);
+ return 0;
+}
diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index ed64790..af43c47 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -48,6 +48,7 @@ int test__mmap_thread_lookup(void);
int test__thread_mg_share(void);
int test__hists_output(void);
int test__hists_cumulate(void);
+int test__group_read_bug(void);
#if defined(__x86_64__) || defined(__i386__) || defined(__arm__)
#ifdef HAVE_DWARF_UNWIND_SUPPORT
--
1.8.3.1
--
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