ring-buffer: Unlock resize on mmap error

rostedt · mehmetb0 · commit 0273e78cff7b · 2025-03-31T17:02:04.000+03:00
BugLink: https://bugs.launchpad.net/bugs/2104873 commit 9ba0e17 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Noah Wager <noah.wager@canonical.com>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
@@ -6423,6 +6423,7 @@ 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
`@@ -6423,6 +6423,7 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu,`
`6423`	`6423`	`kfree(cpu_buffer->subbuf_ids);`
`6424`	`6424`	`cpu_buffer->subbuf_ids = NULL;`
`6425`	`6425`	`rb_free_meta_page(cpu_buffer);`
	`6426`	`+ atomic_dec(&cpu_buffer->resize_disabled);`
`6426`	`6427`	`}`
`6427`	`6428`
`6428`	`6429`	`unlock:`