From 5a9cbf82422507d9d8b3c76ff3638a1f3bc0767e Mon Sep 17 00:00:00 2001 From: Zheng Yejian Date: Wed, 5 Jul 2023 08:27:05 +0800 Subject: [PATCH] tracing: Set actual size after ring buffer resize [ Upstream commit 6d98a0f2ac3c021d21be66fa34e992137cd25bcb ] Currently we can resize trace ringbuffer by writing a value into file 'buffer_size_kb', then by reading the file, we get the value that is usually what we wrote. However, this value may be not actual size of trace ring buffer because of the round up when doing resize in kernel, and the actual size would be more useful. Link: https://lore.kernel.org/linux-trace-kernel/20230705002705.576633-1-zhengyejian1@huawei.com Cc: Signed-off-by: Zheng Yejian Signed-off-by: Steven Rostedt (Google) Stable-dep-of: d78ab792705c ("tracing: Stop current tracer when resizing buffer") Signed-off-by: Sasha Levin --- kernel/trace/trace.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index dc35f9150af7..049daa6a9ad4 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6190,6 +6190,15 @@ static void set_buffer_entries(struct array_buffer *buf, unsigned long val) per_cpu_ptr(buf->data, cpu)->entries = val; } +static void update_buffer_entries(struct array_buffer *buf, int cpu) +{ + if (cpu == RING_BUFFER_ALL_CPUS) { + set_buffer_entries(buf, ring_buffer_size(buf->buffer, 0)); + } else { + per_cpu_ptr(buf->data, cpu)->entries = ring_buffer_size(buf->buffer, cpu); + } +} + #ifdef CONFIG_TRACER_MAX_TRACE /* resize @tr's buffer to the size of @size_tr's entries */ static int resize_buffer_duplicate_size(struct array_buffer *trace_buf, @@ -6267,18 +6276,12 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, return ret; } - if (cpu == RING_BUFFER_ALL_CPUS) - set_buffer_entries(&tr->max_buffer, size); - else - per_cpu_ptr(tr->max_buffer.data, cpu)->entries = size; + update_buffer_entries(&tr->max_buffer, cpu); out: #endif /* CONFIG_TRACER_MAX_TRACE */ - if (cpu == RING_BUFFER_ALL_CPUS) - set_buffer_entries(&tr->array_buffer, size); - else - per_cpu_ptr(tr->array_buffer.data, cpu)->entries = size; + update_buffer_entries(&tr->array_buffer, cpu); return ret; }