xdp: Allow registering memory model without rxq reference

The functions that register an XDP memory model take a struct xdp_rxq as
parameter, but the RXQ is not actually used for anything other than pulling
out the struct xdp_mem_info that it embeds. So refactor the register
functions and export variants that just take a pointer to the xdp_mem_info.

This is in preparation for enabling XDP_REDIRECT in bpf_prog_run(), using a
page_pool instance that is not connected to any network device.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220103150812.87914-2-toke@redhat.com

diff --git a/include/net/xdp.h b/include/net/xdp.h
index 447f9b1..8f0812e 100644 (file)
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -260,6 +260,9 @@ bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
                               enum xdp_mem_type type, void *allocator);
 void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq);
+int xdp_reg_mem_model(struct xdp_mem_info *mem,
+                     enum xdp_mem_type type, void *allocator);
+void xdp_unreg_mem_model(struct xdp_mem_info *mem);
 
 /* Drivers not supporting XDP metadata can use this helper, which
  * rejects any room expansion for metadata as a result.

diff --git a/net/core/xdp.c b/net/core/xdp.c
index 7fe1df8..58089f6 100644 (file)
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -110,20 +110,15 @@ static void mem_allocator_disconnect(void *allocator)
        mutex_unlock(&mem_id_lock);
 }
 
-void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
+void xdp_unreg_mem_model(struct xdp_mem_info *mem)
 {
        struct xdp_mem_allocator *xa;
-       int type = xdp_rxq->mem.type;
-       int id = xdp_rxq->mem.id;
+       int type = mem->type;
+       int id = mem->id;
 
        /* Reset mem info to defaults */
-       xdp_rxq->mem.id = 0;
-       xdp_rxq->mem.type = 0;
-
-       if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
-               WARN(1, "Missing register, driver bug");
-               return;
-       }
+       mem->id = 0;
+       mem->type = 0;
 
        if (id == 0)
                return;
@@ -135,6 +130,17 @@ void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
                rcu_read_unlock();
        }
 }
+EXPORT_SYMBOL_GPL(xdp_unreg_mem_model);
+
+void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
+{
+       if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
+               WARN(1, "Missing register, driver bug");
+               return;
+       }
+
+       xdp_unreg_mem_model(&xdp_rxq->mem);
+}
 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg_mem_model);
 
 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
@@ -259,28 +265,24 @@ static bool __is_supported_mem_type(enum xdp_mem_type type)
        return true;
 }
 
-int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
-                              enum xdp_mem_type type, void *allocator)
+static struct xdp_mem_allocator *__xdp_reg_mem_model(struct xdp_mem_info *mem,
+                                                    enum xdp_mem_type type,
+                                                    void *allocator)
 {
        struct xdp_mem_allocator *xdp_alloc;
        gfp_t gfp = GFP_KERNEL;
        int id, errno, ret;
        void *ptr;
 
-       if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
-               WARN(1, "Missing register, driver bug");
-               return -EFAULT;
-       }
-
        if (!__is_supported_mem_type(type))
-               return -EOPNOTSUPP;
+               return ERR_PTR(-EOPNOTSUPP);
 
-       xdp_rxq->mem.type = type;
+       mem->type = type;
 
        if (!allocator) {
                if (type == MEM_TYPE_PAGE_POOL)
-                       return -EINVAL; /* Setup time check page_pool req */
-               return 0;
+                       return ERR_PTR(-EINVAL); /* Setup time check page_pool req */
+               return NULL;
        }
 
        /* Delay init of rhashtable to save memory if feature isn't used */
@@ -290,13 +292,13 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
                mutex_unlock(&mem_id_lock);
                if (ret < 0) {
                        WARN_ON(1);
-                       return ret;
+                       return ERR_PTR(ret);
                }
        }
 
        xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
        if (!xdp_alloc)
-               return -ENOMEM;
+               return ERR_PTR(-ENOMEM);
 
        mutex_lock(&mem_id_lock);
        id = __mem_id_cyclic_get(gfp);
@@ -304,15 +306,15 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
                errno = id;
                goto err;
        }
-       xdp_rxq->mem.id = id;
-       xdp_alloc->mem  = xdp_rxq->mem;
+       mem->id = id;
+       xdp_alloc->mem = *mem;
        xdp_alloc->allocator = allocator;
 
        /* Insert allocator into ID lookup table */
        ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
        if (IS_ERR(ptr)) {
-               ida_simple_remove(&mem_id_pool, xdp_rxq->mem.id);
-               xdp_rxq->mem.id = 0;
+               ida_simple_remove(&mem_id_pool, mem->id);
+               mem->id = 0;
                errno = PTR_ERR(ptr);
                goto err;
        }
@@ -322,13 +324,43 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 
        mutex_unlock(&mem_id_lock);
 
-       trace_mem_connect(xdp_alloc, xdp_rxq);
-       return 0;
+       return xdp_alloc;
 err:
        mutex_unlock(&mem_id_lock);
        kfree(xdp_alloc);
-       return errno;
+       return ERR_PTR(errno);
+}
+
+int xdp_reg_mem_model(struct xdp_mem_info *mem,
+                     enum xdp_mem_type type, void *allocator)
+{
+       struct xdp_mem_allocator *xdp_alloc;
+
+       xdp_alloc = __xdp_reg_mem_model(mem, type, allocator);
+       if (IS_ERR(xdp_alloc))
+               return PTR_ERR(xdp_alloc);
+       return 0;
+}
+EXPORT_SYMBOL_GPL(xdp_reg_mem_model);
+
+int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
+                              enum xdp_mem_type type, void *allocator)
+{
+       struct xdp_mem_allocator *xdp_alloc;
+
+       if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
+               WARN(1, "Missing register, driver bug");
+               return -EFAULT;
+       }
+
+       xdp_alloc = __xdp_reg_mem_model(&xdp_rxq->mem, type, allocator);
+       if (IS_ERR(xdp_alloc))
+               return PTR_ERR(xdp_alloc);
+
+       trace_mem_connect(xdp_alloc, xdp_rxq);
+       return 0;
 }
+
 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);
 
 /* XDP RX runs under NAPI protection, and in different delivery error