linux-kernel - [PATCH] ring-buffer: Remove jump to out label in ring_buffer_swap

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Message-ID: <20250527145753.6b45d840@gandalf.local.home>
Date: Tue, 27 May 2025 14:57:53 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: LKML <linux-kernel@...r.kernel.org>, Linux Trace Kernel
 <linux-trace-kernel@...r.kernel.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers
 <mathieu.desnoyers@...icios.com>
Subject: [PATCH] ring-buffer: Remove jump to out label in
 ring_buffer_swap_cpu()

From: Steven Rostedt <rostedt@...dmis.org>

The function ring_buffer_swap_cpu() has a bunch of jumps to the label out
that simply returns "ret". There's no reason to jump to a label that
simply returns a value. Just return directly from there.

This goes back to almost the beginning when commit 8aabee573dff
("ring-buffer: remove unneeded get_online_cpus") was introduced. That
commit removed a put_online_cpus() from that label, but never updated all
the jumps to it that now no longer needed to do anything but return a
value.

Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 kernel/trace/ring_buffer.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 897ce51d3bbf..e2aa90dc8d9e 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -6309,37 +6309,33 @@ int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
 
 	if (!cpumask_test_cpu(cpu, buffer_a->cpumask) ||
 	    !cpumask_test_cpu(cpu, buffer_b->cpumask))
-		goto out;
+		return -EINVAL;
 
 	cpu_buffer_a = buffer_a->buffers[cpu];
 	cpu_buffer_b = buffer_b->buffers[cpu];
 
 	/* It's up to the callers to not try to swap mapped buffers */
-	if (WARN_ON_ONCE(cpu_buffer_a->mapped || cpu_buffer_b->mapped)) {
-		ret = -EBUSY;
-		goto out;
-	}
+	if (WARN_ON_ONCE(cpu_buffer_a->mapped || cpu_buffer_b->mapped))
+		return -EBUSY;
 
 	/* At least make sure the two buffers are somewhat the same */
 	if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages)
-		goto out;
+		return -EINVAL;
 
 	if (buffer_a->subbuf_order != buffer_b->subbuf_order)
-		goto out;
-
-	ret = -EAGAIN;
+		return -EINVAL;
 
 	if (atomic_read(&buffer_a->record_disabled))
-		goto out;
+		return -EAGAIN;
 
 	if (atomic_read(&buffer_b->record_disabled))
-		goto out;
+		return -EAGAIN;
 
 	if (atomic_read(&cpu_buffer_a->record_disabled))
-		goto out;
+		return -EAGAIN;
 
 	if (atomic_read(&cpu_buffer_b->record_disabled))
-		goto out;
+		return -EAGAIN;
 
 	/*
 	 * We can't do a synchronize_rcu here because this
@@ -6376,7 +6372,6 @@ int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
 out_dec:
 	atomic_dec(&cpu_buffer_a->record_disabled);
 	atomic_dec(&cpu_buffer_b->record_disabled);
-out:
 	return ret;
 }
 EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu);
-- 
2.47.2