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Subject[for-next][PATCH 07/16] ring-buffer: Do no swap cpu buffers if order is different
From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

As all the subbuffer order (subbuffer sizes) must be the same throughout
the ring buffer, check the order of the buffers that are doing a CPU
buffer swap in ring_buffer_swap_cpu() to make sure they are the same.

If the are not the same, then fail to do the swap, otherwise the ring
buffer will think the CPU buffer has a specific subbuffer size when it
does not.

Link: https://lore.kernel.org/linux-trace-kernel/20231219185629.467894710@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/ring_buffer.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 3c11e8e811ed..fdcd171b09b5 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -5417,6 +5417,9 @@ int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages)
goto out;

+ if (buffer_a->subbuf_order != buffer_b->subbuf_order)
+ goto out;
+
ret = -EAGAIN;

if (atomic_read(&buffer_a->record_disabled))
--
2.42.0


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