linux-kernel - [PATCH 4.19 171/191] ring-buffer: Return 0 on success from ring_buffer

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Message-Id: <20201103203248.569720345@linuxfoundation.org>
Date:   Tue,  3 Nov 2020 21:37:43 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Qiujun Huang <hqjagain@...il.com>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Subject: [PATCH 4.19 171/191] ring-buffer: Return 0 on success from ring_buffer_resize()

From: Qiujun Huang <hqjagain@...il.com>

commit 0a1754b2a97efa644aa6e84d1db5b17c42251483 upstream.

We don't need to check the new buffer size, and the return value
had confused resize_buffer_duplicate_size().
...
	ret = ring_buffer_resize(trace_buf->buffer,
		per_cpu_ptr(size_buf->data,cpu_id)->entries, cpu_id);
	if (ret == 0)
		per_cpu_ptr(trace_buf->data, cpu_id)->entries =
			per_cpu_ptr(size_buf->data, cpu_id)->entries;
...

Link: https://lkml.kernel.org/r/20201019142242.11560-1-hqjagain@gmail.com

Cc: stable@...r.kernel.org
Fixes: d60da506cbeb3 ("tracing: Add a resize function to make one buffer equivalent to another buffer")
Signed-off-by: Qiujun Huang <hqjagain@...il.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/trace/ring_buffer.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1692,18 +1692,18 @@ int ring_buffer_resize(struct ring_buffe
 {
 	struct ring_buffer_per_cpu *cpu_buffer;
 	unsigned long nr_pages;
-	int cpu, err = 0;
+	int cpu, err;
 
 	/*
 	 * Always succeed at resizing a non-existent buffer:
 	 */
 	if (!buffer)
-		return size;
+		return 0;
 
 	/* Make sure the requested buffer exists */
 	if (cpu_id != RING_BUFFER_ALL_CPUS &&
 	    !cpumask_test_cpu(cpu_id, buffer->cpumask))
-		return size;
+		return 0;
 
 	nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
 
@@ -1843,7 +1843,7 @@ int ring_buffer_resize(struct ring_buffe
 	}
 
 	mutex_unlock(&buffer->mutex);
-	return size;
+	return 0;
 
  out_err:
 	for_each_buffer_cpu(buffer, cpu) {