Re: [PATCH] nbd/server: improve nbd_negotiate_send_rep_list

[Eric Blake]

On 12/26/19 2:15 AM, Vladimir Sementsov-Ogievskiy wrote:
> Don't try to write zero-lenght strings.

length

> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
>   nbd/server.c | 16 ++++++++++------
>   1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/nbd/server.c b/nbd/server.c
> index 24ebc1a805..28a915f5a2 100644
> --- a/nbd/server.c
> +++ b/nbd/server.c
> @@ -392,14 +392,18 @@ static int nbd_negotiate_send_rep_list(NBDClient *client, 
> NBDExport *exp,
>           return -EINVAL;
>       }
>   
> -    if (nbd_write(ioc, name, name_len, errp) < 0) {
> -        error_prepend(errp, "write failed (name buffer): ");
> -        return -EINVAL;
> +    if (name_len > 0) {
> +        if (nbd_write(ioc, name, name_len, errp) < 0) {

What's the rationale for this change?  nbd_write() should be a no-op for 
a zero length write, at which point this is a micro-optimization (fewer 
CPU cycles, but no semantic change).

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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