Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 320 insertions, 0 deletions

diff --git a/Documentation/networking/mctp.rst b/Documentation/networking/mctp.rst
new file mode 100644
index 000000000..c628cb540
--- /dev/null
+++ b/Documentation/networking/mctp.rst
@@ -0,0 +1,320 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============================================
+Management Component Transport Protocol (MCTP)
+==============================================
+
+net/mctp/ contains protocol support for MCTP, as defined by DMTF standard
+DSP0236. Physical interface drivers ("bindings" in the specification) are
+provided in drivers/net/mctp/.
+
+The core code provides a socket-based interface to send and receive MCTP
+messages, through an AF_MCTP, SOCK_DGRAM socket.
+
+Structure: interfaces & networks
+================================
+
+The kernel models the local MCTP topology through two items: interfaces and
+networks.
+
+An interface (or "link") is an instance of an MCTP physical transport binding
+(as defined by DSP0236, section 3.2.47), likely connected to a specific hardware
+device. This is represented as a ``struct netdevice``.
+
+A network defines a unique address space for MCTP endpoints by endpoint-ID
+(described by DSP0236, section 3.2.31). A network has a user-visible identifier
+to allow references from userspace. Route definitions are specific to one
+network.
+
+Interfaces are associated with one network. A network may be associated with one
+or more interfaces.
+
+If multiple networks are present, each may contain endpoint IDs (EIDs) that are
+also present on other networks.
+
+Sockets API
+===========
+
+Protocol definitions
+--------------------
+
+MCTP uses ``AF_MCTP`` / ``PF_MCTP`` for the address- and protocol- families.
+Since MCTP is message-based, only ``SOCK_DGRAM`` sockets are supported.
+
+.. code-block:: C
+
+    int sd = socket(AF_MCTP, SOCK_DGRAM, 0);
+
+The only (current) value for the ``protocol`` argument is 0.
+
+As with all socket address families, source and destination addresses are
+specified with a ``sockaddr`` type, with a single-byte endpoint address:
+
+.. code-block:: C
+
+    typedef __u8		mctp_eid_t;
+
+    struct mctp_addr {
+            mctp_eid_t		s_addr;
+    };
+
+    struct sockaddr_mctp {
+            __kernel_sa_family_t smctp_family;
+            unsigned int         smctp_network;
+            struct mctp_addr     smctp_addr;
+            __u8                 smctp_type;
+            __u8                 smctp_tag;
+    };
+
+    #define MCTP_NET_ANY	0x0
+    #define MCTP_ADDR_ANY	0xff
+
+
+Syscall behaviour
+-----------------
+
+The following sections describe the MCTP-specific behaviours of the standard
+socket system calls. These behaviours have been chosen to map closely to the
+existing sockets APIs.
+
+``bind()`` : set local socket address
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Sockets that receive incoming request packets will bind to a local address,
+using the ``bind()`` syscall.
+
+.. code-block:: C
+
+    struct sockaddr_mctp addr;
+
+    addr.smctp_family = AF_MCTP;
+    addr.smctp_network = MCTP_NET_ANY;
+    addr.smctp_addr.s_addr = MCTP_ADDR_ANY;
+    addr.smctp_type = MCTP_TYPE_PLDM;
+    addr.smctp_tag = MCTP_TAG_OWNER;
+
+    int rc = bind(sd, (struct sockaddr *)&addr, sizeof(addr));
+
+This establishes the local address of the socket. Incoming MCTP messages that
+match the network, address, and message type will be received by this socket.
+The reference to 'incoming' is important here; a bound socket will only receive
+messages with the TO bit set, to indicate an incoming request message, rather
+than a response.
+
+The ``smctp_tag`` value will configure the tags accepted from the remote side of
+this socket. Given the above, the only valid value is ``MCTP_TAG_OWNER``, which
+will result in remotely "owned" tags being routed to this socket. Since
+``MCTP_TAG_OWNER`` is set, the 3 least-significant bits of ``smctp_tag`` are not
+used; callers must set them to zero.
+
+A ``smctp_network`` value of ``MCTP_NET_ANY`` will configure the socket to
+receive incoming packets from any locally-connected network. A specific network
+value will cause the socket to only receive incoming messages from that network.
+
+The ``smctp_addr`` field specifies a local address to bind to. A value of
+``MCTP_ADDR_ANY`` configures the socket to receive messages addressed to any
+local destination EID.
+
+The ``smctp_type`` field specifies which message types to receive. Only the
+lower 7 bits of the type is matched on incoming messages (ie., the
+most-significant IC bit is not part of the match). This results in the socket
+receiving packets with and without a message integrity check footer.
+
+``sendto()``, ``sendmsg()``, ``send()`` : transmit an MCTP message
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+An MCTP message is transmitted using one of the ``sendto()``, ``sendmsg()`` or
+``send()`` syscalls. Using ``sendto()`` as the primary example:
+
+.. code-block:: C
+
+    struct sockaddr_mctp addr;
+    char buf[14];
+    ssize_t len;
+
+    /* set message destination */
+    addr.smctp_family = AF_MCTP;
+    addr.smctp_network = 0;
+    addr.smctp_addr.s_addr = 8;
+    addr.smctp_tag = MCTP_TAG_OWNER;
+    addr.smctp_type = MCTP_TYPE_ECHO;
+
+    /* arbitrary message to send, with message-type header */
+    buf[0] = MCTP_TYPE_ECHO;
+    memcpy(buf + 1, "hello, world!", sizeof(buf) - 1);
+
+    len = sendto(sd, buf, sizeof(buf), 0,
+                    (struct sockaddr_mctp *)&addr, sizeof(addr));
+
+The network and address fields of ``addr`` define the remote address to send to.
+If ``smctp_tag`` has the ``MCTP_TAG_OWNER``, the kernel will ignore any bits set
+in ``MCTP_TAG_VALUE``, and generate a tag value suitable for the destination
+EID. If ``MCTP_TAG_OWNER`` is not set, the message will be sent with the tag
+value as specified. If a tag value cannot be allocated, the system call will
+report an errno of ``EAGAIN``.
+
+The application must provide the message type byte as the first byte of the
+message buffer passed to ``sendto()``. If a message integrity check is to be
+included in the transmitted message, it must also be provided in the message
+buffer, and the most-significant bit of the message type byte must be 1.
+
+The ``sendmsg()`` system call allows a more compact argument interface, and the
+message buffer to be specified as a scatter-gather list. At present no ancillary
+message types (used for the ``msg_control`` data passed to ``sendmsg()``) are
+defined.
+
+Transmitting a message on an unconnected socket with ``MCTP_TAG_OWNER``
+specified will cause an allocation of a tag, if no valid tag is already
+allocated for that destination. The (destination-eid,tag) tuple acts as an
+implicit local socket address, to allow the socket to receive responses to this
+outgoing message. If any previous allocation has been performed (to for a
+different remote EID), that allocation is lost.
+
+Sockets will only receive responses to requests they have sent (with TO=1) and
+may only respond (with TO=0) to requests they have received.
+
+``recvfrom()``, ``recvmsg()``, ``recv()`` : receive an MCTP message
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+An MCTP message can be received by an application using one of the
+``recvfrom()``, ``recvmsg()``, or ``recv()`` system calls. Using ``recvfrom()``
+as the primary example:
+
+.. code-block:: C
+
+    struct sockaddr_mctp addr;
+    socklen_t addrlen;
+    char buf[14];
+    ssize_t len;
+
+    addrlen = sizeof(addr);
+
+    len = recvfrom(sd, buf, sizeof(buf), 0,
+                    (struct sockaddr_mctp *)&addr, &addrlen);
+
+    /* We can expect addr to describe an MCTP address */
+    assert(addrlen >= sizeof(buf));
+    assert(addr.smctp_family == AF_MCTP);
+
+    printf("received %zd bytes from remote EID %d\n", rc, addr.smctp_addr);
+
+The address argument to ``recvfrom`` and ``recvmsg`` is populated with the
+remote address of the incoming message, including tag value (this will be needed
+in order to reply to the message).
+
+The first byte of the message buffer will contain the message type byte. If an
+integrity check follows the message, it will be included in the received buffer.
+
+The ``recv()`` system call behaves in a similar way, but does not provide a
+remote address to the application. Therefore, these are only useful if the
+remote address is already known, or the message does not require a reply.
+
+Like the send calls, sockets will only receive responses to requests they have
+sent (TO=1) and may only respond (TO=0) to requests they have received.
+
+``ioctl(SIOCMCTPALLOCTAG)`` and ``ioctl(SIOCMCTPDROPTAG)``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+These tags give applications more control over MCTP message tags, by allocating
+(and dropping) tag values explicitly, rather than the kernel automatically
+allocating a per-message tag at ``sendmsg()`` time.
+
+In general, you will only need to use these ioctls if your MCTP protocol does
+not fit the usual request/response model. For example, if you need to persist
+tags across multiple requests, or a request may generate more than one response.
+In these cases, the ioctls allow you to decouple the tag allocation (and
+release) from individual message send and receive operations.
+
+Both ioctls are passed a pointer to a ``struct mctp_ioc_tag_ctl``:
+
+.. code-block:: C
+
+    struct mctp_ioc_tag_ctl {
+        mctp_eid_t      peer_addr;
+        __u8		tag;
+        __u16   	flags;
+    };
+
+``SIOCMCTPALLOCTAG`` allocates a tag for a specific peer, which an application
+can use in future ``sendmsg()`` calls. The application populates the
+``peer_addr`` member with the remote EID. Other fields must be zero.
+
+On return, the ``tag`` member will be populated with the allocated tag value.
+The allocated tag will have the following tag bits set:
+
+ - ``MCTP_TAG_OWNER``: it only makes sense to allocate tags if you're the tag
+   owner
+
+ - ``MCTP_TAG_PREALLOC``: to indicate to ``sendmsg()`` that this is a
+   preallocated tag.
+
+ - ... and the actual tag value, within the least-significant three bits
+   (``MCTP_TAG_MASK``). Note that zero is a valid tag value.
+
+The tag value should be used as-is for the ``smctp_tag`` member of ``struct
+sockaddr_mctp``.
+
+``SIOCMCTPDROPTAG`` releases a tag that has been previously allocated by a
+``SIOCMCTPALLOCTAG`` ioctl. The ``peer_addr`` must be the same as used for the
+allocation, and the ``tag`` value must match exactly the tag returned from the
+allocation (including the ``MCTP_TAG_OWNER`` and ``MCTP_TAG_PREALLOC`` bits).
+The ``flags`` field must be zero.
+
+Kernel internals
+================
+
+There are a few possible packet flows in the MCTP stack:
+
+1. local TX to remote endpoint, message <= MTU::
+
+	sendmsg()
+	 -> mctp_local_output()
+	    : route lookup
+	    -> rt->output() (== mctp_route_output)
+	       -> dev_queue_xmit()
+
+2. local TX to remote endpoint, message > MTU::
+
+	sendmsg()
+	-> mctp_local_output()
+	    -> mctp_do_fragment_route()
+	       : creates packet-sized skbs. For each new skb:
+	       -> rt->output() (== mctp_route_output)
+	          -> dev_queue_xmit()
+
+3. remote TX to local endpoint, single-packet message::
+
+	mctp_pkttype_receive()
+	: route lookup
+	-> rt->output() (== mctp_route_input)
+	   : sk_key lookup
+	   -> sock_queue_rcv_skb()
+
+4. remote TX to local endpoint, multiple-packet message::
+
+	mctp_pkttype_receive()
+	: route lookup
+	-> rt->output() (== mctp_route_input)
+	   : sk_key lookup
+	   : stores skb in struct sk_key->reasm_head
+
+	mctp_pkttype_receive()
+	: route lookup
+	-> rt->output() (== mctp_route_input)
+	   : sk_key lookup
+	   : finds existing reassembly in sk_key->reasm_head
+	   : appends new fragment
+	   -> sock_queue_rcv_skb()
+
+Key refcounts
+-------------
+
+ * keys are refed by:
+
+   - a skb: during route output, stored in ``skb->cb``.
+
+   - netns and sock lists.
+
+ * keys can be associated with a device, in which case they hold a
+   reference to the dev (set through ``key->dev``, counted through
+   ``dev->key_count``). Multiple keys can reference the device.