[lttng-ust] Fix: remove uninitialised value

Commit 973eac638e4fd introduces an uninitialised value that may prevent
shared memory from being allocated. The compiler didn't give any warning
because the pointer to the value is sent to a function that don't do anything
with it. We simply pass NULL to that function.
---
 liblttng-ust/lttng-ust-comm.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

Merged into master, 2.11, 2.10, 2.9, thanks!

Mathieu

----- On Jul 29, 2019, at 11:14 AM, Gabriel-Andrew Pollo-Guilbert gabriel.pollo-guilbert at efficios.com wrote:

> Commit 973eac638e4fd introduces an uninitialised value that may prevent
> shared memory from being allocated. The compiler didn't give any warning
> because the pointer to the value is sent to a function that don't do anything
> with it. We simply pass NULL to that function.
> ---
> liblttng-ust/lttng-ust-comm.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
> index 4bc350e2..a299ba84 100644
> --- a/liblttng-ust/lttng-ust-comm.c
> +++ b/liblttng-ust/lttng-ust-comm.c
> @@ -875,17 +875,14 @@ int handle_message(struct sock_info *sock_info,
> 	}
> 	case LTTNG_UST_STREAM:
> 	{
> -		uint64_t memory_map_size;
> -
> 		/* Receive shm_fd, wakeup_fd */
> 		ret = ustcomm_recv_stream_from_sessiond(sock,
> -			&memory_map_size,
> +			NULL,
> 			&args.stream.shm_fd,
> 			&args.stream.wakeup_fd);
> 		if (ret) {
> 			goto error;
> 		}
> -		lum->u.stream.len = memory_map_size;
> 
> 		if (ops->cmd)
> 			ret = ops->cmd(lum->handle, lum->cmd,
> --
> 2.22.0