Add a doc in Documentation/networking
Signed-off-by: Tom Herbert <t...@quantonium.net>
---
Documentation/networking/ulp.txt | 82 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 82 insertions(+)
create mode 100644 Documentation/networking/ulp.txt
diff --git a/Documentation/networking/ulp.txt b/Documentation/networking/ulp.txt
new file mode 100644
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+Upper Layer Protocol (ULP) Infrastructure
+=========================================
+
+The ULP kernel infrastructure provides a means to hook upper layer
+protocol support on a socket. A module may register a ULP hook
+in the kernel. ULP processing is enabled by a setsockopt on a socket
+that specifies the name of the registered ULP to invoked. An
+initialization function is defined for each ULP that can change the
+function entry points of the socket (sendmsg, rcvmsg, etc.) or change
+the socket in other fundamental ways.
+
+Note, no synchronization is enforced between the setsockopt to enable
+a ULP and ongoing asynchronous operations on the socket (such as a
+blocked read). If synchronization is required this must be handled by
+the ULP and caller.
+
+User interface
+==============
+
+The structure for the socket SOL_ULP options is defined in socket.h.
+
+Example to enable "my_ulp" ULP on a socket:
+
+struct ulp_config ulpc = {
+ .ulp_name = "my_ulp",
+};
+
+setsockopt(sock, SOL_SOCKET, SO_ULP, &ulpc, sizeof(ulpc))
+
+The ulp_config struct includes a "__u8 ulp_params[0]" field that may be
+used to refer ULP specific parameters being set.
+
+Kernel interface
+================
+
+The interface for ULP infrastructure is defined in net/ulp_sock.h.
+
+ULP registration functions
+--------------------------
+
+int ulp_register(struct ulp_ops *type)
+
+ Called to register a ULP. The ulp_ops structure is described below.
+
+void ulp_unregister(struct ulp_ops *type);
+
+ Called to unregister a ULP.
+
+ulp_ops structure
+-----------------
+
+int (*init)(struct sock *sk, char __user *optval, int len)
+
+ Initialization function for the ULP. This is called from setsockopt
+ when the ULP name in the ulp_config argument matches the registered
+ ULP. optval is a userspace pointer to the ULP specific parameters.
+ len is the length of the ULP specific parameters.
+
+void (*release)(struct sock *sk)
+
+ Called when socket is being destroyed. The ULP implementation
+ should cancel any asynchronous operations (such as timers) and
+ release any acquired resources.
+
+int (*get_params)(struct sock *sk, char __user *optval, int *optlen)
+
+ Get the ULP specific parameters previous set in the init function
+ for the ULP. Note that optlen is a pointer to kernel memory.
+
+char name[ULP_NAME_MAX]
+
+ Name of the ULP. Must be NULL terminated.
+
+struct module *owner
+
+ Corresponding owner for ref count.
+
+Author
+======
+
+Tom Herbert (t...@quantonium.net)
+
--
2.11.0
