Re: [uml-devel] VDE backend does not handle EINTR properly

[Richard Weinberger <richard@sigma-star.at>]

Am 20.11.2011 00:16, schrieb Frank Laub:
> When running the VDE backend with 2 uml instances and running iperf 
> between them, the vde_send() function often returns EINTR. I noticed 
> that this is accounted for in net_user.c via the use of the 
> CATCH_EINTR() macro. Thus the following patch uses the same approach for 
> calls into VDE. It could be argued that the VDE library itself should 
> handle EINTR, but this patch will work with older (or current) versions 
> of VDE. This patch was created against 3.0.3.

Please add a Signed-off-by tag,
so that I can give you the credit. :-)
See: http://linux.yyz.us/patch-format.html

> --- a/arch/um/drivers/vde_user.c
> +++ b/arch/um/drivers/vde_user.c
> @@ -11,6 +11,7 @@
>   #include "um_malloc.h"
>   #include "user.h"
>   #include "vde.h"
> +#include "os.h"
> 
>   static int vde_user_init(void *data, void *dev)
>   {
> @@ -103,7 +104,7 @@ int vde_user_read(void *conn, void *buf,
>       if (vconn == NULL)
>           return 0;
> 
> -    rv = vde_recv(vconn, buf, len, 0);
> +    CATCH_EINTR(rv = vde_recv(vconn, buf, len, 0));
>       if (rv < 0) {
>           if (errno == EAGAIN)
>               return 0;
> @@ -118,10 +119,19 @@ int vde_user_read(void *conn, void *buf,
>   int vde_user_write(void *conn, void *buf, int len)
>   {
>       VDECONN *vconn = conn;
> +    int rv;
> 
>       if (vconn == NULL)
>           return 0;
> 
> -    return vde_send(vconn, buf, len, 0);

Is the additional if-branch really needed?

> +    CATCH_EINTR(rv = vde_send(vconn, buf, len, 0));
> +    if (rv < 0) {
> +        if (errno == EAGAIN)
> +            return 0;
> +        return -errno;
> +    }
> +    else if (rv == 0)
> +        return -ENOTCONN;
> +    return rv;
>   }
> 

Thanks,
//richard

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