Re: [PATCH trace-cmd 2/2] trace-recorder: better error handling during copy

From: Steven Rostedt
Date: Tue Mar 22 2016 - 09:20:14 EST


On Tue, 22 Mar 2016 09:14:33 -0400
Peter Xu <peterx@xxxxxxxxxx> wrote:

> Currently we have two ways to copy data, one is splice, one is read +
> write. For both, dump more information when we got errors during the
> copy. Also, when we update_fd(), we should make sure all bytes written,
> and update written bytes only.
>
> These information might be important to better diagnose when the copy
> got wrong, like no space error, or connection error when copying data to
> remote sockets. In the past, we just got silence errors without notice.
>
> Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
> ---
> trace-recorder.c | 34 ++++++++++++++++++++++++----------
> 1 file changed, 24 insertions(+), 10 deletions(-)
>
> diff --git a/trace-recorder.c b/trace-recorder.c
> index 49b04ea..7d6feb0 100644
> --- a/trace-recorder.c
> +++ b/trace-recorder.c
> @@ -334,13 +334,14 @@ static inline void update_fd(struct tracecmd_recorder *recorder, int size)
> */
> static long splice_data(struct tracecmd_recorder *recorder)
> {
> - long ret;
> + long ret, written;
>
> ret = splice(recorder->trace_fd, NULL, recorder->brass[1], NULL,
> recorder->page_size, 1 /* SPLICE_F_MOVE */);
> if (ret < 0) {
> if (errno != EAGAIN && errno != EINTR) {
> - warning("recorder error in splice input");
> + warning("recorder error in splice input: %s",
> + strerror(errno));

I'm wondering if we should add a "pwarning()" helper function that will
do the stderror(error) for us.

-- Steve

> return -1;
> }