BMC/Intel-BMC/linux.git/include/net/xdp_sock.h, branch v4.19

xsk: fix potential race in SKB TX completion code

2018-07-03T01:37:12+00:00

There is a potential race in the TX completion code for the SKB case. One process enters the sendmsg code of an AF_XDP socket in order to send a frame. The execution eventually trickles down to the driver that is told to send the packet. However, it decides to drop the packet due to some error condition (e.g., rings full) and frees the SKB. This will trigger the SKB destructor and a completion will be sent to the AF_XDP user space through its single-producer/single-consumer queues. At the same time a TX interrupt has fired on another core and it dispatches the TX completion code in the driver. It does its HW specific things and ends up freeing the SKB associated with the transmitted packet. This will trigger the SKB destructor and a completion will be sent to the AF_XDP user space through its single-producer/single-consumer queues. With a pseudo call stack, it would look like this: Core 1: sendmsg() being called in the application netdev_start_xmit() Driver entered through ndo_start_xmit Driver decides to free the SKB for some reason (e.g., rings full) Destructor of SKB called xskq_produce_addr() is called to signal completion to user space Core 2: TX completion irq NAPI loop Driver irq handler for TX completions Frees the SKB Destructor of SKB called xskq_produce_addr() is called to signal completion to user space We now have a violation of the single-producer/single-consumer principle for our queues as there are two threads trying to produce at the same time on the same queue. Fixed by introducing a spin_lock in the destructor. In regards to the performance, I get around 1.74 Mpps for txonly before and after the introduction of the spinlock. There is of course some impact due to the spin lock but it is in the less significant digits that are too noisy for me to measure. But let us say that the version without the spin lock got 1.745 Mpps in the best case and the version with 1.735 Mpps in the worst case, then that would mean a maximum drop in performance of 0.5%. Fixes: 35fcde7f8deb ("xsk: support for Tx") Signed-off-by: Magnus Karlsson Signed-off-by: Alexei Starovoitov

xsk: wire upp Tx zero-copy functions

2018-06-05T13:48:34+00:00

Here we add the functionality required to support zero-copy Tx, and also exposes various zero-copy related functions for the netdevs. Signed-off-by: Magnus Karlsson Signed-off-by: Daniel Borkmann

xsk: add zero-copy support for Rx

2018-06-05T13:46:55+00:00

Extend the xsk_rcv to support the new MEM_TYPE_ZERO_COPY memory, and wireup ndo_bpf call in bind. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann

xsk: introduce xdp_umem_page

2018-06-05T13:45:41+00:00

The xdp_umem_page holds the address for a page. Trade memory for faster lookup. Later, we'll add DMA address here as well. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann

xsk: moved struct xdp_umem definition

2018-06-05T13:45:17+00:00

Moved struct xdp_umem to xdp_sock.h, in order to prepare for zero-copy support. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann

xsk: clean up SPDX headers

2018-05-18T14:07:02+00:00

Clean up SPDX-License-Identifier and removing licensing leftovers. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann

xsk: add Tx queue setup and mmap support

2018-05-03T22:55:24+00:00

Another setsockopt (XDP_TX_QUEUE) is added to let the process allocate a queue, where the user process can pass frames to be transmitted by the kernel. The mmapping of the queue is done using the XDP_PGOFF_TX_QUEUE offset. Signed-off-by: Magnus Karlsson Signed-off-by: Alexei Starovoitov

bpf: introduce new bpf AF_XDP map type BPF_MAP_TYPE_XSKMAP

2018-05-03T22:55:24+00:00

The xskmap is yet another BPF map, very much inspired by dev/cpu/sockmap, and is a holder of AF_XDP sockets. A user application adds AF_XDP sockets into the map, and by using the bpf_redirect_map helper, an XDP program can redirect XDP frames to an AF_XDP socket. Note that a socket that is bound to certain ifindex/queue index will *only* accept XDP frames from that netdev/queue index. If an XDP program tries to redirect from a netdev/queue index other than what the socket is bound to, the frame will not be received on the socket. A socket can reside in multiple maps. v3: Fixed race and simplified code. v2: Removed one indirection in map lookup. Signed-off-by: Björn Töpel Signed-off-by: Alexei Starovoitov

xsk: add Rx receive functions and poll support

2018-05-03T22:55:24+00:00

Here the actual receive functions of AF_XDP are implemented, that in a later commit, will be called from the XDP layers. There's one set of functions for the XDP_DRV side and another for XDP_SKB (generic). A new XDP API, xdp_return_buff, is also introduced. Adding xdp_return_buff, which is analogous to xdp_return_frame, but acts upon an struct xdp_buff. The API will be used by AF_XDP in future commits. Support for the poll syscall is also implemented. v2: xskq_validate_id did not update cons_tail. The entries variable was calculated twice in xskq_nb_avail. Squashed xdp_return_buff commit. Signed-off-by: Björn Töpel Signed-off-by: Alexei Starovoitov

xsk: add support for bind for Rx

2018-05-03T22:55:23+00:00

Here, the bind syscall is added. Binding an AF_XDP socket, means associating the socket to an umem, a netdev and a queue index. This can be done in two ways. The first way, creating a "socket from scratch". Create the umem using the XDP_UMEM_REG setsockopt and an associated fill queue with XDP_UMEM_FILL_QUEUE. Create the Rx queue using the XDP_RX_QUEUE setsockopt. Call bind passing ifindex and queue index ("channel" in ethtool speak). The second way to bind a socket, is simply skipping the umem/netdev/queue index, and passing another already setup AF_XDP socket. The new socket will then have the same umem/netdev/queue index as the parent so it will share the same umem. You must also set the flags field in the socket address to XDP_SHARED_UMEM. v2: Use PTR_ERR instead of passing error variable explicitly. Signed-off-by: Magnus Karlsson Signed-off-by: Alexei Starovoitov