ring-buffer: Do not show buffer_meta for CPUs without a buffer

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The per_cpu/cpuN/buffer_meta files are created for every possible CPU,
but buffer->buffers[cpu] is only allocated once that CPU comes online.
Reading the file of a CPU that never came online dereferences a NULL
cpu_buffer in rbm_start().

Fail the open with -ENODEV when the CPU has no buffer, as the other
per CPU ring buffer interfaces do.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260914133506.4865-3-devnexen@gmail.com
Fixes: 950032ffce ("ring-buffer: Add output of ring buffer meta page")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/20260913134906.6E8A01F000FF@smtp.kernel.org/
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

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David Carlier 2026-09-14 14:35:05 +01:00 • committed by Steven Rostedt

parent 2afe7575fb

commit 3f23cae09a

1 changed files with 3 additions and 0 deletions

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kernel/trace/ring_buffer.c

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