On Sat, 09 Dec 2023 13:27:08 +0100 gregkh@linuxfoundation.org wrote:
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 b538bf7d0ec11ca49f536dfda742a5f6db90a798 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023120908-crisply-trash-d37e@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..
Possible dependencies:
b538bf7d0ec1 ("tracing: Disable snapshot buffer when stopping instance tracers") 13292494379f ("tracing: Make struct ring_buffer less ambiguous") 1c5eb4481e01 ("tracing: Rename trace_buffer to array_buffer") 2d6425af6116 ("tracing: Declare newly exported APIs in include/linux/trace.h")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From b538bf7d0ec11ca49f536dfda742a5f6db90a798 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Google)" rostedt@goodmis.org Date: Tue, 5 Dec 2023 16:52:11 -0500 Subject: [PATCH] tracing: Disable snapshot buffer when stopping instance tracers
This is the fix for 5.4.265, although running tests on it, there appears to be other issues with snapshot and 5.4.265 with and without this patch.
I don't have time to investigate though.
-- Steve
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d7ca8f97b315..a1967c46af12 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2039,13 +2039,7 @@ int is_tracing_stopped(void) return global_trace.stop_count; }
-/** - * tracing_start - quick start of the tracer - * - * If tracing is enabled but was stopped by tracing_stop, - * this will start the tracer back up. - */ -void tracing_start(void) +static void tracing_start_tr(struct trace_array *tr) { struct ring_buffer *buffer; unsigned long flags; @@ -2053,119 +2047,83 @@ void tracing_start(void) if (tracing_disabled) return;
- raw_spin_lock_irqsave(&global_trace.start_lock, flags); - if (--global_trace.stop_count) { - if (global_trace.stop_count < 0) { + raw_spin_lock_irqsave(&tr->start_lock, flags); + if (--tr->stop_count) { + if (WARN_ON_ONCE(tr->stop_count < 0)) { /* Someone screwed up their debugging */ - WARN_ON_ONCE(1); - global_trace.stop_count = 0; + tr->stop_count = 0; } goto out; }
/* Prevent the buffers from switching */ - arch_spin_lock(&global_trace.max_lock); + arch_spin_lock(&tr->max_lock);
- buffer = global_trace.trace_buffer.buffer; + buffer = tr->trace_buffer.buffer; if (buffer) ring_buffer_record_enable(buffer);
#ifdef CONFIG_TRACER_MAX_TRACE - buffer = global_trace.max_buffer.buffer; + buffer = tr->max_buffer.buffer; if (buffer) ring_buffer_record_enable(buffer); #endif
- arch_spin_unlock(&global_trace.max_lock); - - out: - raw_spin_unlock_irqrestore(&global_trace.start_lock, flags); -} - -static void tracing_start_tr(struct trace_array *tr) -{ - struct ring_buffer *buffer; - unsigned long flags; - - if (tracing_disabled) - return; - - /* If global, we need to also start the max tracer */ - if (tr->flags & TRACE_ARRAY_FL_GLOBAL) - return tracing_start(); - - raw_spin_lock_irqsave(&tr->start_lock, flags); - - if (--tr->stop_count) { - if (tr->stop_count < 0) { - /* Someone screwed up their debugging */ - WARN_ON_ONCE(1); - tr->stop_count = 0; - } - goto out; - } - - buffer = tr->trace_buffer.buffer; - if (buffer) - ring_buffer_record_enable(buffer); + arch_spin_unlock(&tr->max_lock);
out: raw_spin_unlock_irqrestore(&tr->start_lock, flags); }
/** - * tracing_stop - quick stop of the tracer + * tracing_start - quick start of the tracer * - * Light weight way to stop tracing. Use in conjunction with - * tracing_start. + * If tracing is enabled but was stopped by tracing_stop, + * this will start the tracer back up. */ -void tracing_stop(void) +void tracing_start(void) + +{ + return tracing_start_tr(&global_trace); +} + +static void tracing_stop_tr(struct trace_array *tr) { struct ring_buffer *buffer; unsigned long flags;
- raw_spin_lock_irqsave(&global_trace.start_lock, flags); - if (global_trace.stop_count++) + raw_spin_lock_irqsave(&tr->start_lock, flags); + if (tr->stop_count++) goto out;
/* Prevent the buffers from switching */ - arch_spin_lock(&global_trace.max_lock); + arch_spin_lock(&tr->max_lock);
- buffer = global_trace.trace_buffer.buffer; + buffer = tr->trace_buffer.buffer; if (buffer) ring_buffer_record_disable(buffer);
#ifdef CONFIG_TRACER_MAX_TRACE - buffer = global_trace.max_buffer.buffer; + buffer = tr->max_buffer.buffer; if (buffer) ring_buffer_record_disable(buffer); #endif
- arch_spin_unlock(&global_trace.max_lock); + arch_spin_unlock(&tr->max_lock);
out: - raw_spin_unlock_irqrestore(&global_trace.start_lock, flags); + raw_spin_unlock_irqrestore(&tr->start_lock, flags); }
-static void tracing_stop_tr(struct trace_array *tr) +/** + * tracing_stop - quick stop of the tracer + * + * Light weight way to stop tracing. Use in conjunction with + * tracing_start. + */ +void tracing_stop(void) { - struct ring_buffer *buffer; - unsigned long flags; - - /* If global, we need to also stop the max tracer */ - if (tr->flags & TRACE_ARRAY_FL_GLOBAL) - return tracing_stop(); - - raw_spin_lock_irqsave(&tr->start_lock, flags); - if (tr->stop_count++) - goto out; - - buffer = tr->trace_buffer.buffer; - if (buffer) - ring_buffer_record_disable(buffer); - - out: - raw_spin_unlock_irqrestore(&tr->start_lock, flags); + return tracing_stop_tr(&global_trace); }
static int trace_save_cmdline(struct task_struct *tsk)