Re: [LTP] [PATCH V3 2/2] tst_checkpoint_signal_child: implemented timeout

[Jan Stancek <jstancek@redhat.com>]

----- Original Message -----
> From: "Stanislav Kholmanskikh" <stanislav.kholmanskikh@oracle.com>
> To: ltp-list@lists.sourceforge.net
> Cc: "vasily isaenko" <vasily.isaenko@oracle.com>
> Sent: Thursday, 14 November, 2013 7:37:57 AM
> Subject: [LTP] [PATCH V3 2/2] tst_checkpoint_signal_child: implemented	timeout
> 
> If a child exits before opening TST_CHECKPOINT_FIFO
> for reading, tst_checkpoint_signal_child() issued from the parent
> will block forever.
> 
> To handle such situations added timeout logic to
> tst_checkpoint_signal_child();
> 
> Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>

One small nit: the comment should say ">= 0", other than that, it looks good to me:
Reviewed-by: Jan Stancek <jstancek@redhat.com>

I'm sending a follow-up patch (tst_checkpoint_child_exits2), which I used to verify this one.

Regards,
Jan

> ---
>  lib/tst_checkpoint.c |   36 +++++++++++++++++++++++++++++++++++-
>  1 files changed, 35 insertions(+), 1 deletions(-)
> 
> diff --git a/lib/tst_checkpoint.c b/lib/tst_checkpoint.c
> index 56c86b5..e53c499 100644
> --- a/lib/tst_checkpoint.c
> +++ b/lib/tst_checkpoint.c
> @@ -33,6 +33,40 @@
>  
>  #include "tst_checkpoint.h"
>  
> +/*
> + * Issue open() on 'path' fifo with O_WRONLY flag and wait for
> + * a reader up to 'timeout' ms.
> + *
> + * Returns:
> + *   > 0 - file descriptor
> + *   -1  - an error has occurred (errno is set accordingly)
> + *
> + */
> +int open_wronly_timed(const char *path, unsigned int timeout)
> +{
> +	int fd;
> +	int i;
> +	int interval = 1; /* how often issue open(O_NONBLOCK), in ms */
> +
> +	for (i = 0; i < timeout; i += interval) {
> +		fd = open(path, O_WRONLY | O_NONBLOCK);
> +		if (fd < 0) {
> +			if ((errno == ENXIO) || (errno == EINTR)) {
> +				usleep(interval * 1000);
> +
> +				continue;
> +			}
> +
> +			return -1;
> +		}
> +
> +		return fd;
> +	}
> +
> +	errno = ETIMEDOUT;
> +	return -1;
> +}
> +
>  void tst_checkpoint_init(const char *file, const int lineno,
>                           struct tst_checkpoint *self)
>  {
> @@ -195,7 +229,7 @@ void tst_checkpoint_signal_child(const char *file, const
> int lineno,
>  {
>  	int ret, fd;
>  	
> -	fd = open(TST_CHECKPOINT_FIFO, O_WRONLY);
> +	fd = open_wronly_timed(TST_CHECKPOINT_FIFO, self->timeout);
>  
>  	if (fd < 0) {
>  		tst_brkm(TBROK | TERRNO, cleanup_fn,
> --
> 1.7.1
> 
> 
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