linux-kernel - [PATCH v3 38/57] perf: Simplify IOC_SET

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Message-ID: <20230612093540.253514702@infradead.org>
Date:   Mon, 12 Jun 2023 11:07:51 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     torvalds@...ux-foundation.org, keescook@...omium.org,
        gregkh@...uxfoundation.org, pbonzini@...hat.com
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Subject: [PATCH v3 38/57] perf: Simplify IOC_SET_OUTPUT


Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/events/core.c |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5762,6 +5762,11 @@ static inline struct fd perf_fdget(int f
 	return f;
 }
 
+static inline bool is_perf_fd(struct fd fd)
+{
+	return fd.file && fd.file->f_op == &perf_fops;
+}
+
 static int perf_event_set_output(struct perf_event *event,
 				 struct perf_event *output_event);
 static int perf_event_set_filter(struct perf_event *event, void __user *arg);
@@ -5807,19 +5812,15 @@ static long _perf_ioctl(struct perf_even
 
 	case PERF_EVENT_IOC_SET_OUTPUT:
 	{
-		int ret;
 		if (arg != -1) {
 			struct perf_event *output_event;
-			struct fd output = perf_fdget(arg);
-			if (!output.file)
+			CLASS(fd, output)(arg);
+			if (!is_perf_fd(output))
 				return -EBADF;
 			output_event = output.file->private_data;
-			ret = perf_event_set_output(event, output_event);
-			fdput(output);
-		} else {
-			ret = perf_event_set_output(event, NULL);
+			return perf_event_set_output(event, output_event);
 		}
-		return ret;
+		return perf_event_set_output(event, NULL);
 	}
 
 	case PERF_EVENT_IOC_SET_FILTER: