The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x d06aff1cb13d2a0d52b48e605462518149c98c81 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023121801-lustfully-gulf-2543@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

d06aff1cb13d ("tracing: Update snapshot buffer on resize if it is allocated") d78ab792705c ("tracing: Stop current tracer when resizing buffer") 7be76461f302 ("tracing: Always update snapshot buffer size") 6d98a0f2ac3c ("tracing: Set actual size after ring buffer resize") 1c5eb4481e01 ("tracing: Rename trace_buffer to array_buffer")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d06aff1cb13d2a0d52b48e605462518149c98c81 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" rostedt@goodmis.org Date: Sun, 10 Dec 2023 22:54:47 -0500 Subject: [PATCH] tracing: Update snapshot buffer on resize if it is allocated

The snapshot buffer is to mimic the main buffer so that when a snapshot is needed, the snapshot and main buffer are swapped. When the snapshot buffer is allocated, it is set to the minimal size that the ring buffer may be at and still functional. When it is allocated it becomes the same size as the main ring buffer, and when the main ring buffer changes in size, it should do.

Currently, the resize only updates the snapshot buffer if it's used by the current tracer (ie. the preemptirqsoff tracer). But it needs to be updated anytime it is allocated.

When changing the size of the main buffer, instead of looking to see if the current tracer is utilizing the snapshot buffer, just check if it is allocated to know if it should be updated or not.

Also fix typo in comment just above the code change.

Link: https://lore.kernel.org/linux-trace-kernel/20231210225447.48476a6a@rorschach...

Cc: stable@vger.kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Mathieu Desnoyers mathieu.desnoyers@efficios.com Fixes: ad909e21bbe69 ("tracing: Add internal tracing_snapshot() functions") Reviewed-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index aa8f99f3e5de..6c79548f9574 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6348,7 +6348,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, if (!tr->array_buffer.buffer) return 0;

- /* Do not allow tracing while resizng ring buffer */ + /* Do not allow tracing while resizing ring buffer */ tracing_stop_tr(tr);

ret = ring_buffer_resize(tr->array_buffer.buffer, size, cpu); @@ -6356,7 +6356,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, goto out_start;

#ifdef CONFIG_TRACER_MAX_TRACE - if (!tr->current_trace->use_max_tr) + if (!tr->allocated_snapshot) goto out;

ret = ring_buffer_resize(tr->max_buffer.buffer, size, cpu);