Messages in this thread | | | Date | Fri, 16 Nov 2012 16:34:12 +0800 | From | Shan Wei <> | Subject | Re: [PATCH v4 7/9] trace: use this_cpu_ptr per-cpu helper |
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Shan Wei said, at 2012/11/13 9:53: > From: Shan Wei <davidshan@tencent.com> > > 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. > > Signed-off-by: Shan Wei <davidshan@tencent.com>
Steven Rostedt, would you like to pick it up to your tree?
> --- > v4: avoid type cast using &percpu_buffer->buffer[0]. > --- > kernel/trace/blktrace.c | 2 +- > kernel/trace/trace.c | 5 +---- > 2 files changed, 2 insertions(+), 5 deletions(-) > > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c > index c0bd030..71259e2 100644 > --- a/kernel/trace/blktrace.c > +++ b/kernel/trace/blktrace.c > @@ -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); > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 31e4f55..65cb003 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -1495,7 +1495,6 @@ 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 > @@ -1513,9 +1512,7 @@ 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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