From e03e7ee34fdd1c3ef494949a75cb8c61c7265fa9 Mon Sep 17 00:00:00 2001
From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date: Mon, 25 Jan 2016 20:59:49 -0800
Subject: perf/bpf: Convert perf_event_array to use struct file

Robustify refcounting.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160126045947.GA40151@ast-mbp.thefacebook.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/events/core.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

(limited to 'kernel/events/core.c')

diff --git a/kernel/events/core.c b/kernel/events/core.c
index fe97f95f204e..eb44730afea5 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8916,21 +8916,20 @@ void perf_event_delayed_put(struct task_struct *task)
 		WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
 }
 
-struct perf_event *perf_event_get(unsigned int fd)
+struct file *perf_event_get(unsigned int fd)
 {
-	int err;
-	struct fd f;
-	struct perf_event *event;
+	struct file *file;
 
-	err = perf_fget_light(fd, &f);
-	if (err)
-		return ERR_PTR(err);
+	file = fget_raw(fd);
+	if (!file)
+		return ERR_PTR(-EBADF);
 
-	event = f.file->private_data;
-	atomic_long_inc(&event->refcount);
-	fdput(f);
+	if (file->f_op != &perf_fops) {
+		fput(file);
+		return ERR_PTR(-EBADF);
+	}
 
-	return event;
+	return file;
 }
 
 const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
-- 
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