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, 230 insertions, 0 deletions

diff --git a/Documentation/networking/phonet.rst b/Documentation/networking/phonet.rst
new file mode 100644
index 000000000..d705cc5b0
--- /dev/null
+++ b/Documentation/networking/phonet.rst
@@ -0,0 +1,230 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+============================
+Linux Phonet protocol family
+============================
+
+Introduction
+------------
+
+Phonet is a packet protocol used by Nokia cellular modems for both IPC
+and RPC. With the Linux Phonet socket family, Linux host processes can
+receive and send messages from/to the modem, or any other external
+device attached to the modem. The modem takes care of routing.
+
+Phonet packets can be exchanged through various hardware connections
+depending on the device, such as:
+
+  - USB with the CDC Phonet interface,
+  - infrared,
+  - Bluetooth,
+  - an RS232 serial port (with a dedicated "FBUS" line discipline),
+  - the SSI bus with some TI OMAP processors.
+
+
+Packets format
+--------------
+
+Phonet packets have a common header as follows::
+
+  struct phonethdr {
+    uint8_t  pn_media;  /* Media type (link-layer identifier) */
+    uint8_t  pn_rdev;   /* Receiver device ID */
+    uint8_t  pn_sdev;   /* Sender device ID */
+    uint8_t  pn_res;    /* Resource ID or function */
+    uint16_t pn_length; /* Big-endian message byte length (minus 6) */
+    uint8_t  pn_robj;   /* Receiver object ID */
+    uint8_t  pn_sobj;   /* Sender object ID */
+  };
+
+On Linux, the link-layer header includes the pn_media byte (see below).
+The next 7 bytes are part of the network-layer header.
+
+The device ID is split: the 6 higher-order bits constitute the device
+address, while the 2 lower-order bits are used for multiplexing, as are
+the 8-bit object identifiers. As such, Phonet can be considered as a
+network layer with 6 bits of address space and 10 bits for transport
+protocol (much like port numbers in IP world).
+
+The modem always has address number zero. All other device have a their
+own 6-bit address.
+
+
+Link layer
+----------
+
+Phonet links are always point-to-point links. The link layer header
+consists of a single Phonet media type byte. It uniquely identifies the
+link through which the packet is transmitted, from the modem's
+perspective. Each Phonet network device shall prepend and set the media
+type byte as appropriate. For convenience, a common phonet_header_ops
+link-layer header operations structure is provided. It sets the
+media type according to the network device hardware address.
+
+Linux Phonet network interfaces support a dedicated link layer packets
+type (ETH_P_PHONET) which is out of the Ethernet type range. They can
+only send and receive Phonet packets.
+
+The virtual TUN tunnel device driver can also be used for Phonet. This
+requires IFF_TUN mode, _without_ the IFF_NO_PI flag. In this case,
+there is no link-layer header, so there is no Phonet media type byte.
+
+Note that Phonet interfaces are not allowed to re-order packets, so
+only the (default) Linux FIFO qdisc should be used with them.
+
+
+Network layer
+-------------
+
+The Phonet socket address family maps the Phonet packet header::
+
+  struct sockaddr_pn {
+    sa_family_t spn_family;    /* AF_PHONET */
+    uint8_t     spn_obj;       /* Object ID */
+    uint8_t     spn_dev;       /* Device ID */
+    uint8_t     spn_resource;  /* Resource or function */
+    uint8_t     spn_zero[...]; /* Padding */
+  };
+
+The resource field is only used when sending and receiving;
+It is ignored by bind() and getsockname().
+
+
+Low-level datagram protocol
+---------------------------
+
+Applications can send Phonet messages using the Phonet datagram socket
+protocol from the PF_PHONET family. Each socket is bound to one of the
+2^10 object IDs available, and can send and receive packets with any
+other peer.
+
+::
+
+  struct sockaddr_pn addr = { .spn_family = AF_PHONET, };
+  ssize_t len;
+  socklen_t addrlen = sizeof(addr);
+  int fd;
+
+  fd = socket(PF_PHONET, SOCK_DGRAM, 0);
+  bind(fd, (struct sockaddr *)&addr, sizeof(addr));
+  /* ... */
+
+  sendto(fd, msg, msglen, 0, (struct sockaddr *)&addr, sizeof(addr));
+  len = recvfrom(fd, buf, sizeof(buf), 0,
+		 (struct sockaddr *)&addr, &addrlen);
+
+This protocol follows the SOCK_DGRAM connection-less semantics.
+However, connect() and getpeername() are not supported, as they did
+not seem useful with Phonet usages (could be added easily).
+
+
+Resource subscription
+---------------------
+
+A Phonet datagram socket can be subscribed to any number of 8-bits
+Phonet resources, as follow::
+
+  uint32_t res = 0xXX;
+  ioctl(fd, SIOCPNADDRESOURCE, &res);
+
+Subscription is similarly cancelled using the SIOCPNDELRESOURCE I/O
+control request, or when the socket is closed.
+
+Note that no more than one socket can be subscribed to any given
+resource at a time. If not, ioctl() will return EBUSY.
+
+
+Phonet Pipe protocol
+--------------------
+
+The Phonet Pipe protocol is a simple sequenced packets protocol
+with end-to-end congestion control. It uses the passive listening
+socket paradigm. The listening socket is bound to an unique free object
+ID. Each listening socket can handle up to 255 simultaneous
+connections, one per accept()'d socket.
+
+::
+
+  int lfd, cfd;
+
+  lfd = socket(PF_PHONET, SOCK_SEQPACKET, PN_PROTO_PIPE);
+  listen (lfd, INT_MAX);
+
+  /* ... */
+  cfd = accept(lfd, NULL, NULL);
+  for (;;)
+  {
+    char buf[...];
+    ssize_t len = read(cfd, buf, sizeof(buf));
+
+    /* ... */
+
+    write(cfd, msg, msglen);
+  }
+
+Connections are traditionally established between two endpoints by a
+"third party" application. This means that both endpoints are passive.
+
+
+As of Linux kernel version 2.6.39, it is also possible to connect
+two endpoints directly, using connect() on the active side. This is
+intended to support the newer Nokia Wireless Modem API, as found in
+e.g. the Nokia Slim Modem in the ST-Ericsson U8500 platform::
+
+  struct sockaddr_spn spn;
+  int fd;
+
+  fd = socket(PF_PHONET, SOCK_SEQPACKET, PN_PROTO_PIPE);
+  memset(&spn, 0, sizeof(spn));
+  spn.spn_family = AF_PHONET;
+  spn.spn_obj = ...;
+  spn.spn_dev = ...;
+  spn.spn_resource = 0xD9;
+  connect(fd, (struct sockaddr *)&spn, sizeof(spn));
+  /* normal I/O here ... */
+  close(fd);
+
+
+.. Warning:
+
+   When polling a connected pipe socket for writability, there is an
+   intrinsic race condition whereby writability might be lost between the
+   polling and the writing system calls. In this case, the socket will
+   block until write becomes possible again, unless non-blocking mode
+   is enabled.
+
+
+The pipe protocol provides two socket options at the SOL_PNPIPE level:
+
+  PNPIPE_ENCAP accepts one integer value (int) of:
+
+    PNPIPE_ENCAP_NONE:
+      The socket operates normally (default).
+
+    PNPIPE_ENCAP_IP:
+      The socket is used as a backend for a virtual IP
+      interface. This requires CAP_NET_ADMIN capability. GPRS data
+      support on Nokia modems can use this. Note that the socket cannot
+      be reliably poll()'d or read() from while in this mode.
+
+  PNPIPE_IFINDEX
+      is a read-only integer value. It contains the
+      interface index of the network interface created by PNPIPE_ENCAP,
+      or zero if encapsulation is off.
+
+  PNPIPE_HANDLE
+      is a read-only integer value. It contains the underlying
+      identifier ("pipe handle") of the pipe. This is only defined for
+      socket descriptors that are already connected or being connected.
+
+
+Authors
+-------
+
+Linux Phonet was initially written by Sakari Ailus.
+
+Other contributors include Mikä Liljeberg, Andras Domokos,
+Carlos Chinea and Rémi Denis-Courmont.
+
+Copyright |copy| 2008 Nokia Corporation.