ring-buffer: Unlock resize on mmap error

rostedt · rostedt · commit 9ba0e1755a40 · 2025-02-14T12:50:05.000-05:00
Memory mapping the tracing ring buffer will disable resizing the buffer. But if there's an error in the memory mapping like an invalid parameter, the function exits out without re-enabling the resizing of the ring buffer, preventing the ring buffer from being resized after that. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Vincent Donnefort <vdonnefort@google.com> Link: https://lore.kernel.org/20250213131957.530ec3c5@gandalf.local.home Fixes: 117c392 ("ring-buffer: Introducing ring-buffer mapping functions") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
@@ -7126,6 +7126,7 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu,
 		kfree(cpu_buffer->subbuf_ids);
 		cpu_buffer->subbuf_ids = NULL;
 		rb_free_meta_page(cpu_buffer);
+		atomic_dec(&cpu_buffer->resize_disabled);
 	}
 
 unlock:

Original file line number	Diff line number	Diff line change
`@@ -7126,6 +7126,7 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu,`
`7126`	`7126`	`kfree(cpu_buffer->subbuf_ids);`
`7127`	`7127`	`cpu_buffer->subbuf_ids = NULL;`
`7128`	`7128`	`rb_free_meta_page(cpu_buffer);`
	`7129`	`+ atomic_dec(&cpu_buffer->resize_disabled);`
`7129`	`7130`	`}`
`7130`	`7131`
`7131`	`7132`	`unlock:`