Commit 6d98a0f2 authored by Zheng Yejian's avatar Zheng Yejian Committed by Steven Rostedt (Google)
Browse files

tracing: Set actual size after ring buffer resize 

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: <mhiramat@kernel.org>
Signed-off-by: default avatarZheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 6bba9288

kernel/trace/trace.c

+11 −8
Original line number Diff line number Diff line
@@ -6286,6 +6286,15 @@ 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,
@@ -6364,18 +6373,12 @@ 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;

}