[Spice-devel] [PATCH 6/7] Respect IOV_MAX if defined

[Alon Levy]

On Thu, Feb 16, 2012 at 11:30:12PM -0600, Dan McGee wrote:
> Solaris has a pitiful maximum writev vector size of only 16, so the ping
> request at initial startup destroyed this call and broke things
> immediately. Reimplement stream_writev_cb() to respect IOV_MAX and break
> the writev() calls into chunks as necessary. Care was taken to return
> the correct values as necessary so the EAGAIN handling logic can
> determine where to resume the writev call the next time around.
> 

Isn't this another candidate for ifdeferry?

> Signed-off-by: Dan McGee <dpmcgee at gmail.com>
> ---
>  server/reds.c |   27 ++++++++++++++++++++++++++-
>  1 files changed, 26 insertions(+), 1 deletions(-)
> 
> diff --git a/server/reds.c b/server/reds.c
> index 250e0ca..797d9d5 100644
> --- a/server/reds.c
> +++ b/server/reds.c
> @@ -23,6 +23,7 @@
>  #include <stdio.h>
>  #include <unistd.h>
>  #include <sys/socket.h>
> +#include <sys/uio.h>
>  #include <netinet/in.h>
>  #include <netinet/tcp.h>
>  #include <arpa/inet.h>
> @@ -340,7 +341,31 @@ static ssize_t stream_write_cb(RedsStream *s, const void *buf, size_t size)
>  
>  static ssize_t stream_writev_cb(RedsStream *s, const struct iovec *iov, int iovcnt)
>  {
#ifndef BREAK_WRITEV
> -    return writev(s->socket, iov, iovcnt);
#else
...
> +    ssize_t ret = 0;
> +    do {
> +        int tosend;
> +        ssize_t n, expected = 0;
> +        int i;
> +#ifdef IOV_MAX
> +        tosend = MIN(iovcnt, IOV_MAX);
> +#else
> +        tosend = iovcnt;
> +#endif
> +        for (i = 0; i < tosend; i++) {
> +            expected += iov[i].iov_len;
> +        }
> +        n = writev(s->socket, iov, tosend);
> +        if (n <= expected) {
> +            if (n > 0)
> +                ret += n;
> +            return ret == 0 ? n : ret;
> +        }
> +        ret += n;
> +        iov += tosend;
> +        iovcnt -= tosend;
> +    } while(iovcnt > 0);
> +
> +    return ret;
>  }
>  
>  static ssize_t stream_read_cb(RedsStream *s, void *buf, size_t size)
> -- 
> 1.7.9.1
> 
> _______________________________________________
> Spice-devel mailing list
> Spice-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/spice-devel