tracing: Use this_cpu_ptr per-cpu helper (d8a0349c) · Commits · 戴 / test

typeof(&buffer) is a pointer to array of 1024 char, or char (*)[1024]. But, typeof(&buffer[0]) is a pointer to char which match the return type of get_trace_buf(). As well-known, the value of &buffer is equal to &buffer[0]. so return this_cpu_ptr(&percpu_buffer->buffer[0]) can avoid type cast. Link: http://lkml.kernel.org/r/50A1A800.3020102@gmail.com Reviewed-by:

Christoph Lameter <cl@linux.com> Signed-off-by:

Shan Wei <davidshan@tencent.com> Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

kernel/trace/blktrace.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -147,7 +147,7 @@ void __trace_note_message(struct blk_trace bt, const char fmt, ...)
		return;

		local_irq_save(flags);
		buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
		buf = this_cpu_ptr(bt->msg_data);
		va_start(args, fmt);
		n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
		va_end(args);

kernel/trace/trace.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -1517,7 +1517,6 @@ static struct trace_buffer_struct *trace_percpu_nmi_buffer;
		static char *get_trace_buf(void)
		{
		struct trace_buffer_struct *percpu_buffer;
		struct trace_buffer_struct *buffer;

		/*
		* If we have allocated per cpu buffers, then we do not
		@@ -1535,9 +1534,7 @@ static char *get_trace_buf(void)
		if (!percpu_buffer)
		return NULL;

		buffer = per_cpu_ptr(percpu_buffer, smp_processor_id());

		return buffer->buffer;
		return this_cpu_ptr(&percpu_buffer->buffer[0]);
		}

		static int alloc_percpu_trace_buffer(void)

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