On 2020-07-21 07:04, Magnus Karlsson wrote:
Add support for shared umems between hardware queues and devices to
the AF_XDP part of libbpf. This so that zero-copy can be achieved in
applications that want to send and receive packets between HW queues
on one device or between different devices/netdevs.

In order to create sockets that share a umem between hardware queues
and devices, a new function has been added called
xsk_socket__create_shared(). It takes the same arguments as
xsk_socket_create() plus references to a fill ring and a completion
ring. So for every socket that share a umem, you need to have one more
set of fill and completion rings. This in order to maintain the
single-producer single-consumer semantics of the rings.

You can create all the sockets via the new xsk_socket__create_shared()
call, or create the first one with xsk_socket__create() and the rest
with xsk_socket__create_shared(). Both methods work.

Signed-off-by: Magnus Karlsson <magnus.karls...@intel.com>

Acked-by: Björn Töpel <bjorn.to...@intel.com>


---
  tools/lib/bpf/libbpf.map |   1 +
  tools/lib/bpf/xsk.c      | 376 ++++++++++++++++++++++++++++++-----------------
  tools/lib/bpf/xsk.h      |   9 ++
  3 files changed, 254 insertions(+), 132 deletions(-)

diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 6f0856a..bc06b67 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -291,4 +291,5 @@ LIBBPF_0.1.0 {
                bpf_program__set_autoload;
                bpf_program__set_sk_lookup;
                btf__set_fd;
+               xsk_socket__create_shared;
  } LIBBPF_0.0.9;
diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index f7f4efb..86ad4f7 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -20,6 +20,7 @@
  #include <linux/if_ether.h>
  #include <linux/if_packet.h>
  #include <linux/if_xdp.h>
+#include <linux/list.h>
  #include <linux/sockios.h>
  #include <net/if.h>
  #include <sys/ioctl.h>
@@ -48,26 +49,35 @@
  #endif
struct xsk_umem {
-       struct xsk_ring_prod *fill;
-       struct xsk_ring_cons *comp;
+       struct xsk_ring_prod *fill_save;
+       struct xsk_ring_cons *comp_save;
        char *umem_area;
        struct xsk_umem_config config;
        int fd;
        int refcount;
+       struct list_head ctx_list;
+};
+
+struct xsk_ctx {
+       struct xsk_ring_prod *fill;
+       struct xsk_ring_cons *comp;
+       __u32 queue_id;
+       struct xsk_umem *umem;
+       int refcount;
+       int ifindex;
+       struct list_head list;
+       int prog_fd;
+       int xsks_map_fd;
+       char ifname[IFNAMSIZ];
  };
struct xsk_socket {
        struct xsk_ring_cons *rx;
        struct xsk_ring_prod *tx;
        __u64 outstanding_tx;
-       struct xsk_umem *umem;
+       struct xsk_ctx *ctx;
        struct xsk_socket_config config;
        int fd;
-       int ifindex;
-       int prog_fd;
-       int xsks_map_fd;
-       __u32 queue_id;
-       char ifname[IFNAMSIZ];
  };
struct xsk_nl_info {
@@ -203,15 +213,73 @@ static int xsk_get_mmap_offsets(int fd, struct 
xdp_mmap_offsets *off)
        return -EINVAL;
  }
+static int xsk_create_umem_rings(struct xsk_umem *umem, int fd,
+                                struct xsk_ring_prod *fill,
+                                struct xsk_ring_cons *comp)
+{
+       struct xdp_mmap_offsets off;
+       void *map;
+       int err;
+
+       err = setsockopt(fd, SOL_XDP, XDP_UMEM_FILL_RING,
+                        &umem->config.fill_size,
+                        sizeof(umem->config.fill_size));
+       if (err)
+               return -errno;
+
+       err = setsockopt(fd, SOL_XDP, XDP_UMEM_COMPLETION_RING,
+                        &umem->config.comp_size,
+                        sizeof(umem->config.comp_size));
+       if (err)
+               return -errno;
+
+       err = xsk_get_mmap_offsets(fd, &off);
+       if (err)
+               return -errno;
+
+       map = mmap(NULL, off.fr.desc + umem->config.fill_size * sizeof(__u64),
+                  PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, fd,
+                  XDP_UMEM_PGOFF_FILL_RING);
+       if (map == MAP_FAILED)
+               return -errno;
+
+       fill->mask = umem->config.fill_size - 1;
+       fill->size = umem->config.fill_size;
+       fill->producer = map + off.fr.producer;
+       fill->consumer = map + off.fr.consumer;
+       fill->flags = map + off.fr.flags;
+       fill->ring = map + off.fr.desc;
+       fill->cached_cons = umem->config.fill_size;
+
+       map = mmap(NULL, off.cr.desc + umem->config.comp_size * sizeof(__u64),
+                  PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, fd,
+                  XDP_UMEM_PGOFF_COMPLETION_RING);
+       if (map == MAP_FAILED) {
+               err = -errno;
+               goto out_mmap;
+       }
+
+       comp->mask = umem->config.comp_size - 1;
+       comp->size = umem->config.comp_size;
+       comp->producer = map + off.cr.producer;
+       comp->consumer = map + off.cr.consumer;
+       comp->flags = map + off.cr.flags;
+       comp->ring = map + off.cr.desc;
+
+       return 0;
+
+out_mmap:
+       munmap(map, off.fr.desc + umem->config.fill_size * sizeof(__u64));
+       return err;
+}
+
  int xsk_umem__create_v0_0_4(struct xsk_umem **umem_ptr, void *umem_area,
                            __u64 size, struct xsk_ring_prod *fill,
                            struct xsk_ring_cons *comp,
                            const struct xsk_umem_config *usr_config)
  {
-       struct xdp_mmap_offsets off;
        struct xdp_umem_reg mr;
        struct xsk_umem *umem;
-       void *map;
        int err;
if (!umem_area || !umem_ptr || !fill || !comp)
@@ -230,6 +298,7 @@ int xsk_umem__create_v0_0_4(struct xsk_umem **umem_ptr, 
void *umem_area,
        }
umem->umem_area = umem_area;
+       INIT_LIST_HEAD(&umem->ctx_list);
        xsk_set_umem_config(&umem->config, usr_config);
memset(&mr, 0, sizeof(mr));
@@ -244,71 +313,16 @@ int xsk_umem__create_v0_0_4(struct xsk_umem **umem_ptr, 
void *umem_area,
                err = -errno;
                goto out_socket;
        }
-       err = setsockopt(umem->fd, SOL_XDP, XDP_UMEM_FILL_RING,
-                        &umem->config.fill_size,
-                        sizeof(umem->config.fill_size));
-       if (err) {
-               err = -errno;
-               goto out_socket;
-       }
-       err = setsockopt(umem->fd, SOL_XDP, XDP_UMEM_COMPLETION_RING,
-                        &umem->config.comp_size,
-                        sizeof(umem->config.comp_size));
-       if (err) {
-               err = -errno;
-               goto out_socket;
-       }
- err = xsk_get_mmap_offsets(umem->fd, &off);
-       if (err) {
-               err = -errno;
-               goto out_socket;
-       }
-
-       map = mmap(NULL, off.fr.desc + umem->config.fill_size * sizeof(__u64),
-                  PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, umem->fd,
-                  XDP_UMEM_PGOFF_FILL_RING);
-       if (map == MAP_FAILED) {
-               err = -errno;
+       err = xsk_create_umem_rings(umem, umem->fd, fill, comp);
+       if (err)
                goto out_socket;
-       }
-
-       umem->fill = fill;
-       fill->mask = umem->config.fill_size - 1;
-       fill->size = umem->config.fill_size;
-       fill->producer = map + off.fr.producer;
-       fill->consumer = map + off.fr.consumer;
-       fill->flags = map + off.fr.flags;
-       fill->ring = map + off.fr.desc;
-       fill->cached_prod = *fill->producer;
-       /* cached_cons is "size" bigger than the real consumer pointer
-        * See xsk_prod_nb_free
-        */
-       fill->cached_cons = *fill->consumer + umem->config.fill_size;
-
-       map = mmap(NULL, off.cr.desc + umem->config.comp_size * sizeof(__u64),
-                  PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, umem->fd,
-                  XDP_UMEM_PGOFF_COMPLETION_RING);
-       if (map == MAP_FAILED) {
-               err = -errno;
-               goto out_mmap;
-       }
-
-       umem->comp = comp;
-       comp->mask = umem->config.comp_size - 1;
-       comp->size = umem->config.comp_size;
-       comp->producer = map + off.cr.producer;
-       comp->consumer = map + off.cr.consumer;
-       comp->flags = map + off.cr.flags;
-       comp->ring = map + off.cr.desc;
-       comp->cached_prod = *comp->producer;
-       comp->cached_cons = *comp->consumer;
+ umem->fill_save = fill;
+       umem->comp_save = comp;
        *umem_ptr = umem;
        return 0;
-out_mmap:
-       munmap(map, off.fr.desc + umem->config.fill_size * sizeof(__u64));
  out_socket:
        close(umem->fd);
  out_umem_alloc:
@@ -342,6 +356,7 @@ DEFAULT_VERSION(xsk_umem__create_v0_0_4, xsk_umem__create, 
LIBBPF_0.0.4)
  static int xsk_load_xdp_prog(struct xsk_socket *xsk)
  {
        static const int log_buf_size = 16 * 1024;
+       struct xsk_ctx *ctx = xsk->ctx;
        char log_buf[log_buf_size];
        int err, prog_fd;
@@ -369,7 +384,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
                /* *(u32 *)(r10 - 4) = r2 */
                BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_2, -4),
                /* r1 = xskmap[] */
-               BPF_LD_MAP_FD(BPF_REG_1, xsk->xsks_map_fd),
+               BPF_LD_MAP_FD(BPF_REG_1, ctx->xsks_map_fd),
                /* r3 = XDP_PASS */
                BPF_MOV64_IMM(BPF_REG_3, 2),
                /* call bpf_redirect_map */
@@ -381,7 +396,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
                /* r2 += -4 */
                BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),
                /* r1 = xskmap[] */
-               BPF_LD_MAP_FD(BPF_REG_1, xsk->xsks_map_fd),
+               BPF_LD_MAP_FD(BPF_REG_1, ctx->xsks_map_fd),
                /* call bpf_map_lookup_elem */
                BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
                /* r1 = r0 */
@@ -393,7 +408,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
                /* r2 = *(u32 *)(r10 - 4) */
                BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_10, -4),
                /* r1 = xskmap[] */
-               BPF_LD_MAP_FD(BPF_REG_1, xsk->xsks_map_fd),
+               BPF_LD_MAP_FD(BPF_REG_1, ctx->xsks_map_fd),
                /* r3 = 0 */
                BPF_MOV64_IMM(BPF_REG_3, 0),
                /* call bpf_redirect_map */
@@ -411,19 +426,21 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
                return prog_fd;
        }
- err = bpf_set_link_xdp_fd(xsk->ifindex, prog_fd, xsk->config.xdp_flags);
+       err = bpf_set_link_xdp_fd(xsk->ctx->ifindex, prog_fd,
+                                 xsk->config.xdp_flags);
        if (err) {
                close(prog_fd);
                return err;
        }
- xsk->prog_fd = prog_fd;
+       ctx->prog_fd = prog_fd;
        return 0;
  }
static int xsk_get_max_queues(struct xsk_socket *xsk)
  {
        struct ethtool_channels channels = { .cmd = ETHTOOL_GCHANNELS };
+       struct xsk_ctx *ctx = xsk->ctx;
        struct ifreq ifr = {};
        int fd, err, ret;
@@ -432,7 +449,7 @@ static int xsk_get_max_queues(struct xsk_socket *xsk)
                return -errno;
ifr.ifr_data = (void *)&channels;
-       memcpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ - 1);
+       memcpy(ifr.ifr_name, ctx->ifname, IFNAMSIZ - 1);
        ifr.ifr_name[IFNAMSIZ - 1] = '\0';
        err = ioctl(fd, SIOCETHTOOL, &ifr);
        if (err && errno != EOPNOTSUPP) {
@@ -460,6 +477,7 @@ static int xsk_get_max_queues(struct xsk_socket *xsk)
static int xsk_create_bpf_maps(struct xsk_socket *xsk)
  {
+       struct xsk_ctx *ctx = xsk->ctx;
        int max_queues;
        int fd;
@@ -472,15 +490,17 @@ static int xsk_create_bpf_maps(struct xsk_socket *xsk)
        if (fd < 0)
                return fd;
- xsk->xsks_map_fd = fd;
+       ctx->xsks_map_fd = fd;
return 0;
  }
static void xsk_delete_bpf_maps(struct xsk_socket *xsk)
  {
-       bpf_map_delete_elem(xsk->xsks_map_fd, &xsk->queue_id);
-       close(xsk->xsks_map_fd);
+       struct xsk_ctx *ctx = xsk->ctx;
+
+       bpf_map_delete_elem(ctx->xsks_map_fd, &ctx->queue_id);
+       close(ctx->xsks_map_fd);
  }
static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)
@@ -488,10 +508,11 @@ static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)
        __u32 i, *map_ids, num_maps, prog_len = sizeof(struct bpf_prog_info);
        __u32 map_len = sizeof(struct bpf_map_info);
        struct bpf_prog_info prog_info = {};
+       struct xsk_ctx *ctx = xsk->ctx;
        struct bpf_map_info map_info;
        int fd, err;
- err = bpf_obj_get_info_by_fd(xsk->prog_fd, &prog_info, &prog_len);
+       err = bpf_obj_get_info_by_fd(ctx->prog_fd, &prog_info, &prog_len);
        if (err)
                return err;
@@ -505,11 +526,11 @@ static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)
        prog_info.nr_map_ids = num_maps;
        prog_info.map_ids = (__u64)(unsigned long)map_ids;
- err = bpf_obj_get_info_by_fd(xsk->prog_fd, &prog_info, &prog_len);
+       err = bpf_obj_get_info_by_fd(ctx->prog_fd, &prog_info, &prog_len);
        if (err)
                goto out_map_ids;
- xsk->xsks_map_fd = -1;
+       ctx->xsks_map_fd = -1;
for (i = 0; i < prog_info.nr_map_ids; i++) {
                fd = bpf_map_get_fd_by_id(map_ids[i]);
@@ -523,7 +544,7 @@ static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)
                }
if (!strcmp(map_info.name, "xsks_map")) {
-                       xsk->xsks_map_fd = fd;
+                       ctx->xsks_map_fd = fd;
                        continue;
                }
@@ -531,7 +552,7 @@ static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)
        }
err = 0;
-       if (xsk->xsks_map_fd == -1)
+       if (ctx->xsks_map_fd == -1)
                err = -ENOENT;
out_map_ids:
@@ -541,16 +562,19 @@ static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)
static int xsk_set_bpf_maps(struct xsk_socket *xsk)
  {
-       return bpf_map_update_elem(xsk->xsks_map_fd, &xsk->queue_id,
+       struct xsk_ctx *ctx = xsk->ctx;
+
+       return bpf_map_update_elem(ctx->xsks_map_fd, &ctx->queue_id,
                                   &xsk->fd, 0);
  }
static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
  {
+       struct xsk_ctx *ctx = xsk->ctx;
        __u32 prog_id = 0;
        int err;
- err = bpf_get_link_xdp_id(xsk->ifindex, &prog_id,
+       err = bpf_get_link_xdp_id(ctx->ifindex, &prog_id,
                                  xsk->config.xdp_flags);
        if (err)
                return err;
@@ -566,12 +590,12 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
                        return err;
                }
        } else {
-               xsk->prog_fd = bpf_prog_get_fd_by_id(prog_id);
-               if (xsk->prog_fd < 0)
+               ctx->prog_fd = bpf_prog_get_fd_by_id(prog_id);
+               if (ctx->prog_fd < 0)
                        return -errno;
                err = xsk_lookup_bpf_maps(xsk);
                if (err) {
-                       close(xsk->prog_fd);
+                       close(ctx->prog_fd);
                        return err;
                }
        }
@@ -580,25 +604,110 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
                err = xsk_set_bpf_maps(xsk);
        if (err) {
                xsk_delete_bpf_maps(xsk);
-               close(xsk->prog_fd);
+               close(ctx->prog_fd);
                return err;
        }
return 0;
  }
-int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
-                      __u32 queue_id, struct xsk_umem *umem,
-                      struct xsk_ring_cons *rx, struct xsk_ring_prod *tx,
-                      const struct xsk_socket_config *usr_config)
+static struct xsk_ctx *xsk_get_ctx(struct xsk_umem *umem, int ifindex,
+                                  __u32 queue_id)
+{
+       struct xsk_ctx *ctx;
+
+       if (list_empty(&umem->ctx_list))
+               return NULL;
+
+       list_for_each_entry(ctx, &umem->ctx_list, list) {
+               if (ctx->ifindex == ifindex && ctx->queue_id == queue_id) {
+                       ctx->refcount++;
+                       return ctx;
+               }
+       }
+
+       return NULL;
+}
+
+static void xsk_put_ctx(struct xsk_ctx *ctx)
+{
+       struct xsk_umem *umem = ctx->umem;
+       struct xdp_mmap_offsets off;
+       int err;
+
+       if (--ctx->refcount == 0) {
+               err = xsk_get_mmap_offsets(umem->fd, &off);
+               if (!err) {
+                       munmap(ctx->fill->ring - off.fr.desc,
+                              off.fr.desc + umem->config.fill_size *
+                              sizeof(__u64));
+                       munmap(ctx->comp->ring - off.cr.desc,
+                              off.cr.desc + umem->config.comp_size *
+                              sizeof(__u64));
+               }
+
+               list_del(&ctx->list);
+               free(ctx);
+       }
+}
+
+static struct xsk_ctx *xsk_create_ctx(struct xsk_socket *xsk,
+                                     struct xsk_umem *umem, int ifindex,
+                                     const char *ifname, __u32 queue_id,
+                                     struct xsk_ring_prod *fill,
+                                     struct xsk_ring_cons *comp)
+{
+       struct xsk_ctx *ctx;
+       int err;
+
+       ctx = calloc(1, sizeof(*ctx));
+       if (!ctx)
+               return NULL;
+
+       if (!umem->fill_save) {
+               err = xsk_create_umem_rings(umem, xsk->fd, fill, comp);
+               if (err) {
+                       free(ctx);
+                       return NULL;
+               }
+       } else if (umem->fill_save != fill || umem->comp_save != comp) {
+               /* Copy over rings to new structs. */
+               memcpy(fill, umem->fill_save, sizeof(*fill));
+               memcpy(comp, umem->comp_save, sizeof(*comp));
+       }
+
+       ctx->ifindex = ifindex;
+       ctx->refcount = 1;
+       ctx->umem = umem;
+       ctx->queue_id = queue_id;
+       memcpy(ctx->ifname, ifname, IFNAMSIZ - 1);
+       ctx->ifname[IFNAMSIZ - 1] = '\0';
+
+       umem->fill_save = NULL;
+       umem->comp_save = NULL;
+       ctx->fill = fill;
+       ctx->comp = comp;
+       list_add(&ctx->list, &umem->ctx_list);
+       return ctx;
+}
+
+int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
+                             const char *ifname,
+                             __u32 queue_id, struct xsk_umem *umem,
+                             struct xsk_ring_cons *rx,
+                             struct xsk_ring_prod *tx,
+                             struct xsk_ring_prod *fill,
+                             struct xsk_ring_cons *comp,
+                             const struct xsk_socket_config *usr_config)
  {
        void *rx_map = NULL, *tx_map = NULL;
        struct sockaddr_xdp sxdp = {};
        struct xdp_mmap_offsets off;
        struct xsk_socket *xsk;
-       int err;
+       struct xsk_ctx *ctx;
+       int err, ifindex;
- if (!umem || !xsk_ptr || !(rx || tx))
+       if (!umem || !xsk_ptr || !(rx || tx) || !fill || !comp)
                return -EFAULT;
xsk = calloc(1, sizeof(*xsk));
@@ -609,10 +718,10 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const 
char *ifname,
        if (err)
                goto out_xsk_alloc;
- if (umem->refcount &&
-           !(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {
-               pr_warn("Error: shared umems not supported by libbpf supplied XDP 
program.\n");
-               err = -EBUSY;
+       xsk->outstanding_tx = 0;
+       ifindex = if_nametoindex(ifname);
+       if (!ifindex) {
+               err = -errno;
                goto out_xsk_alloc;
        }
@@ -626,16 +735,16 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
                xsk->fd = umem->fd;
        }
- xsk->outstanding_tx = 0;
-       xsk->queue_id = queue_id;
-       xsk->umem = umem;
-       xsk->ifindex = if_nametoindex(ifname);
-       if (!xsk->ifindex) {
-               err = -errno;
-               goto out_socket;
+       ctx = xsk_get_ctx(umem, ifindex, queue_id);
+       if (!ctx) {
+               ctx = xsk_create_ctx(xsk, umem, ifindex, ifname, queue_id,
+                                    fill, comp);
+               if (!ctx) {
+                       err = -ENOMEM;
+                       goto out_socket;
+               }
        }
-       memcpy(xsk->ifname, ifname, IFNAMSIZ - 1);
-       xsk->ifname[IFNAMSIZ - 1] = '\0';
+       xsk->ctx = ctx;
if (rx) {
                err = setsockopt(xsk->fd, SOL_XDP, XDP_RX_RING,
@@ -643,7 +752,7 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const 
char *ifname,
                                 sizeof(xsk->config.rx_size));
                if (err) {
                        err = -errno;
-                       goto out_socket;
+                       goto out_put_ctx;
                }
        }
        if (tx) {
@@ -652,14 +761,14 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const 
char *ifname,
                                 sizeof(xsk->config.tx_size));
                if (err) {
                        err = -errno;
-                       goto out_socket;
+                       goto out_put_ctx;
                }
        }
err = xsk_get_mmap_offsets(xsk->fd, &off);
        if (err) {
                err = -errno;
-               goto out_socket;
+               goto out_put_ctx;
        }
if (rx) {
@@ -669,7 +778,7 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const 
char *ifname,
                              xsk->fd, XDP_PGOFF_RX_RING);
                if (rx_map == MAP_FAILED) {
                        err = -errno;
-                       goto out_socket;
+                       goto out_put_ctx;
                }
rx->mask = xsk->config.rx_size - 1;
@@ -708,10 +817,10 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const 
char *ifname,
        xsk->tx = tx;
sxdp.sxdp_family = PF_XDP;
-       sxdp.sxdp_ifindex = xsk->ifindex;
-       sxdp.sxdp_queue_id = xsk->queue_id;
+       sxdp.sxdp_ifindex = ctx->ifindex;
+       sxdp.sxdp_queue_id = ctx->queue_id;
        if (umem->refcount > 1) {
-               sxdp.sxdp_flags = XDP_SHARED_UMEM;
+               sxdp.sxdp_flags |= XDP_SHARED_UMEM;
                sxdp.sxdp_shared_umem_fd = umem->fd;
        } else {
                sxdp.sxdp_flags = xsk->config.bind_flags;
@@ -723,7 +832,7 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const 
char *ifname,
                goto out_mmap_tx;
        }
- xsk->prog_fd = -1;
+       ctx->prog_fd = -1;
if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {
                err = xsk_setup_xdp_prog(xsk);
@@ -742,6 +851,8 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const 
char *ifname,
        if (rx)
                munmap(rx_map, off.rx.desc +
                       xsk->config.rx_size * sizeof(struct xdp_desc));
+out_put_ctx:
+       xsk_put_ctx(ctx);
  out_socket:
        if (--umem->refcount)
                close(xsk->fd);
@@ -750,25 +861,24 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const 
char *ifname,
        return err;
  }
-int xsk_umem__delete(struct xsk_umem *umem)
+int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
+                      __u32 queue_id, struct xsk_umem *umem,
+                      struct xsk_ring_cons *rx, struct xsk_ring_prod *tx,
+                      const struct xsk_socket_config *usr_config)
  {
-       struct xdp_mmap_offsets off;
-       int err;
+       return xsk_socket__create_shared(xsk_ptr, ifname, queue_id, umem,
+                                        rx, tx, umem->fill_save,
+                                        umem->comp_save, usr_config);
+}
+int xsk_umem__delete(struct xsk_umem *umem)
+{
        if (!umem)
                return 0;
if (umem->refcount)
                return -EBUSY;
- err = xsk_get_mmap_offsets(umem->fd, &off);
-       if (!err) {
-               munmap(umem->fill->ring - off.fr.desc,
-                      off.fr.desc + umem->config.fill_size * sizeof(__u64));
-               munmap(umem->comp->ring - off.cr.desc,
-                      off.cr.desc + umem->config.comp_size * sizeof(__u64));
-       }
-
        close(umem->fd);
        free(umem);
@@ -778,15 +888,16 @@ int xsk_umem__delete(struct xsk_umem *umem)
  void xsk_socket__delete(struct xsk_socket *xsk)
  {
        size_t desc_sz = sizeof(struct xdp_desc);
+       struct xsk_ctx *ctx = xsk->ctx;
        struct xdp_mmap_offsets off;
        int err;
if (!xsk)
                return;
- if (xsk->prog_fd != -1) {
+       if (ctx->prog_fd != -1) {
                xsk_delete_bpf_maps(xsk);
-               close(xsk->prog_fd);
+               close(ctx->prog_fd);
        }
err = xsk_get_mmap_offsets(xsk->fd, &off);
@@ -799,14 +910,15 @@ void xsk_socket__delete(struct xsk_socket *xsk)
                        munmap(xsk->tx->ring - off.tx.desc,
                               off.tx.desc + xsk->config.tx_size * desc_sz);
                }
-
        }
- xsk->umem->refcount--;
+       xsk_put_ctx(ctx);
+
+       ctx->umem->refcount--;
        /* Do not close an fd that also has an associated umem connected
         * to it.
         */
-       if (xsk->fd != xsk->umem->fd)
+       if (xsk->fd != ctx->umem->fd)
                close(xsk->fd);
        free(xsk);
  }
diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
index 584f682..1069c46 100644
--- a/tools/lib/bpf/xsk.h
+++ b/tools/lib/bpf/xsk.h
@@ -234,6 +234,15 @@ LIBBPF_API int xsk_socket__create(struct xsk_socket **xsk,
                                  struct xsk_ring_cons *rx,
                                  struct xsk_ring_prod *tx,
                                  const struct xsk_socket_config *config);
+LIBBPF_API int
+xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
+                         const char *ifname,
+                         __u32 queue_id, struct xsk_umem *umem,
+                         struct xsk_ring_cons *rx,
+                         struct xsk_ring_prod *tx,
+                         struct xsk_ring_prod *fill,
+                         struct xsk_ring_cons *comp,
+                         const struct xsk_socket_config *config);
/* Returns 0 for success and -EBUSY if the umem is still in use. */
  LIBBPF_API int xsk_umem__delete(struct xsk_umem *umem);

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