2022-09-19 19:58:34

by Jalal Mostafa

Subject: [PATCH bpf] xsk: inherit need_wakeup flag for shared sockets

The flag for need_wakeup is not set for xsks with `XDP_SHARED_UMEM`
flag and of different queue ids and/or devices. They should inherit
the flag from the first socket buffer pool since no flags can be
specified once `XDP_SHARED_UMEM` is specified. The issue is fixed
by creating a new function `xp_create_and_assign_umem_shared` to
create xsk_buff_pool for xsks with the shared umem flag set.

Signed-off-by: Jalal Mostafa <[email protected]>
---
include/net/xsk_buff_pool.h | 2 ++
net/xdp/xsk.c | 3 +--
net/xdp/xsk_buff_pool.c | 15 +++++++++++++++
3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index 647722e847b4..917cfef9d355 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -93,6 +93,8 @@ struct xsk_buff_pool {
/* AF_XDP core. */
struct xsk_buff_pool *xp_create_and_assign_umem(struct xdp_sock *xs,
struct xdp_umem *umem);
+struct xsk_buff_pool *xp_create_and_assign_umem_shared(struct xdp_sock *xs,
+ struct xdp_sock *umem_xs);
int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *dev,
u16 queue_id, u16 flags);
int xp_assign_dev_shared(struct xsk_buff_pool *pool, struct xdp_umem *umem,
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 5b4ce6ba1bc7..a415db88e8e5 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -946,8 +946,7 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
/* Share the umem with another socket on another qid
* and/or device.
*/
- xs->pool = xp_create_and_assign_umem(xs,
- umem_xs->umem);
+ xs->pool = xp_create_and_assign_umem_shared(xs, umem_xs);
if (!xs->pool) {
err = -ENOMEM;
sockfd_put(sock);
diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
index a71a8c6edf55..7d5b0bd8d953 100644
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -112,6 +112,21 @@ struct xsk_buff_pool *xp_create_and_assign_umem(struct xdp_sock *xs,
return NULL;
}

+struct xsk_buff_pool *xp_create_and_assign_umem_shared(struct xdp_sock *xs,
+ struct xdp_sock *umem_xs)
+{
+ struct xdp_umem *umem = umem_xs->umem;
+ struct xsk_buff_pool *pool = xp_create_and_assign_umem(xs, umem);
+
+ if (!pool)
+ goto out;
+
+ pool->uses_need_wakeup = umem_xs->pool->uses_need_wakeup;
+
+out:
+ return pool;
+}
+
void xp_set_rxq_info(struct xsk_buff_pool *pool, struct xdp_rxq_info *rxq)
{
u32 i;
--
2.34.1

2022-09-20 07:16:23

by Magnus Karlsson

Subject: Re: [PATCH bpf] xsk: inherit need_wakeup flag for shared sockets

On Mon, Sep 19, 2022 at 9:27 PM Jalal Mostafa
<[email protected]> wrote:
>
> The flag for need_wakeup is not set for xsks with `XDP_SHARED_UMEM`
> flag and of different queue ids and/or devices. They should inherit
> the flag from the first socket buffer pool since no flags can be
> specified once `XDP_SHARED_UMEM` is specified. The issue is fixed
> by creating a new function `xp_create_and_assign_umem_shared` to
> create xsk_buff_pool for xsks with the shared umem flag set.

Thanks for spotting this Jalal. Though I think we should aim for a
simpler fix. The uses_need_wakeup flag is set by xp_assign_dev(). The
problem here is the function xp_assign_dev_shared() that prepares the
flag parameter for xp_assign_dev().

if (pool->uses_need_wakeup)
flags |= XDP_USE_NEED_WAKEUP;

Should really be:

if (umem_xs->pool->uses_need_wakeup)
flags |= XDP_USE_NEED_WAKEUP;

So change the function parameter *umem to *umem_xs, use that in the
function call and do:

flags = umem_xs->umem->zc ? XDP_ZEROCOPY : XDP_COPY;
if (umem_xs->pool->uses_need_wakeup)
flags |= XDP_USE_NEED_WAKEUP;

What do you think?

> Signed-off-by: Jalal Mostafa <[email protected]>
> ---
> include/net/xsk_buff_pool.h | 2 ++
> net/xdp/xsk.c | 3 +--
> net/xdp/xsk_buff_pool.c | 15 +++++++++++++++
> 3 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
> index 647722e847b4..917cfef9d355 100644
> --- a/include/net/xsk_buff_pool.h
> +++ b/include/net/xsk_buff_pool.h
> @@ -93,6 +93,8 @@ struct xsk_buff_pool {
> /* AF_XDP core. */
> struct xsk_buff_pool *xp_create_and_assign_umem(struct xdp_sock *xs,
> struct xdp_umem *umem);
> +struct xsk_buff_pool *xp_create_and_assign_umem_shared(struct xdp_sock *xs,
> + struct xdp_sock *umem_xs);
> int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *dev,
> u16 queue_id, u16 flags);
> int xp_assign_dev_shared(struct xsk_buff_pool *pool, struct xdp_umem *umem,
> diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
> index 5b4ce6ba1bc7..a415db88e8e5 100644
> --- a/net/xdp/xsk.c
> +++ b/net/xdp/xsk.c
> @@ -946,8 +946,7 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
> /* Share the umem with another socket on another qid
> * and/or device.
> */
> - xs->pool = xp_create_and_assign_umem(xs,
> - umem_xs->umem);
> + xs->pool = xp_create_and_assign_umem_shared(xs, umem_xs);
> if (!xs->pool) {
> err = -ENOMEM;
> sockfd_put(sock);
> diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
> index a71a8c6edf55..7d5b0bd8d953 100644
> --- a/net/xdp/xsk_buff_pool.c
> +++ b/net/xdp/xsk_buff_pool.c
> @@ -112,6 +112,21 @@ struct xsk_buff_pool *xp_create_and_assign_umem(struct xdp_sock *xs,
> return NULL;
> }
>
> +struct xsk_buff_pool *xp_create_and_assign_umem_shared(struct xdp_sock *xs,
> + struct xdp_sock *umem_xs)
> +{
> + struct xdp_umem *umem = umem_xs->umem;
> + struct xsk_buff_pool *pool = xp_create_and_assign_umem(xs, umem);
> +
> + if (!pool)
> + goto out;
> +
> + pool->uses_need_wakeup = umem_xs->pool->uses_need_wakeup;
> +
> +out:
> + return pool;
> +}
> +
> void xp_set_rxq_info(struct xsk_buff_pool *pool, struct xdp_rxq_info *rxq)
> {
> u32 i;
> --
> 2.34.1
>