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, 305 insertions, 0 deletions

diff --git a/Documentation/networking/lapb-module.rst b/Documentation/networking/lapb-module.rst
new file mode 100644
index 000000000..ff586bc9f
--- /dev/null
+++ b/Documentation/networking/lapb-module.rst
@@ -0,0 +1,305 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===============================
+The Linux LAPB Module Interface
+===============================
+
+Version 1.3
+
+Jonathan Naylor 29.12.96
+
+Changed (Henner Eisen, 2000-10-29): int return value for data_indication()
+
+The LAPB module will be a separately compiled module for use by any parts of
+the Linux operating system that require a LAPB service. This document
+defines the interfaces to, and the services provided by this module. The
+term module in this context does not imply that the LAPB module is a
+separately loadable module, although it may be. The term module is used in
+its more standard meaning.
+
+The interface to the LAPB module consists of functions to the module,
+callbacks from the module to indicate important state changes, and
+structures for getting and setting information about the module.
+
+Structures
+----------
+
+Probably the most important structure is the skbuff structure for holding
+received and transmitted data, however it is beyond the scope of this
+document.
+
+The two LAPB specific structures are the LAPB initialisation structure and
+the LAPB parameter structure. These will be defined in a standard header
+file, <linux/lapb.h>. The header file <net/lapb.h> is internal to the LAPB
+module and is not for use.
+
+LAPB Initialisation Structure
+-----------------------------
+
+This structure is used only once, in the call to lapb_register (see below).
+It contains information about the device driver that requires the services
+of the LAPB module::
+
+	struct lapb_register_struct {
+		void (*connect_confirmation)(int token, int reason);
+		void (*connect_indication)(int token, int reason);
+		void (*disconnect_confirmation)(int token, int reason);
+		void (*disconnect_indication)(int token, int reason);
+		int  (*data_indication)(int token, struct sk_buff *skb);
+		void (*data_transmit)(int token, struct sk_buff *skb);
+	};
+
+Each member of this structure corresponds to a function in the device driver
+that is called when a particular event in the LAPB module occurs. These will
+be described in detail below. If a callback is not required (!!) then a NULL
+may be substituted.
+
+
+LAPB Parameter Structure
+------------------------
+
+This structure is used with the lapb_getparms and lapb_setparms functions
+(see below). They are used to allow the device driver to get and set the
+operational parameters of the LAPB implementation for a given connection::
+
+	struct lapb_parms_struct {
+		unsigned int t1;
+		unsigned int t1timer;
+		unsigned int t2;
+		unsigned int t2timer;
+		unsigned int n2;
+		unsigned int n2count;
+		unsigned int window;
+		unsigned int state;
+		unsigned int mode;
+	};
+
+T1 and T2 are protocol timing parameters and are given in units of 100ms. N2
+is the maximum number of tries on the link before it is declared a failure.
+The window size is the maximum number of outstanding data packets allowed to
+be unacknowledged by the remote end, the value of the window is between 1
+and 7 for a standard LAPB link, and between 1 and 127 for an extended LAPB
+link.
+
+The mode variable is a bit field used for setting (at present) three values.
+The bit fields have the following meanings:
+
+======  =================================================
+Bit	Meaning
+======  =================================================
+0	LAPB operation (0=LAPB_STANDARD 1=LAPB_EXTENDED).
+1	[SM]LP operation (0=LAPB_SLP 1=LAPB=MLP).
+2	DTE/DCE operation (0=LAPB_DTE 1=LAPB_DCE)
+3-31	Reserved, must be 0.
+======  =================================================
+
+Extended LAPB operation indicates the use of extended sequence numbers and
+consequently larger window sizes, the default is standard LAPB operation.
+MLP operation is the same as SLP operation except that the addresses used by
+LAPB are different to indicate the mode of operation, the default is Single
+Link Procedure. The difference between DCE and DTE operation is (i) the
+addresses used for commands and responses, and (ii) when the DCE is not
+connected, it sends DM without polls set, every T1. The upper case constant
+names will be defined in the public LAPB header file.
+
+
+Functions
+---------
+
+The LAPB module provides a number of function entry points.
+
+::
+
+    int lapb_register(void *token, struct lapb_register_struct);
+
+This must be called before the LAPB module may be used. If the call is
+successful then LAPB_OK is returned. The token must be a unique identifier
+generated by the device driver to allow for the unique identification of the
+instance of the LAPB link. It is returned by the LAPB module in all of the
+callbacks, and is used by the device driver in all calls to the LAPB module.
+For multiple LAPB links in a single device driver, multiple calls to
+lapb_register must be made. The format of the lapb_register_struct is given
+above. The return values are:
+
+=============		=============================
+LAPB_OK			LAPB registered successfully.
+LAPB_BADTOKEN		Token is already registered.
+LAPB_NOMEM		Out of memory
+=============		=============================
+
+::
+
+    int lapb_unregister(void *token);
+
+This releases all the resources associated with a LAPB link. Any current
+LAPB link will be abandoned without further messages being passed. After
+this call, the value of token is no longer valid for any calls to the LAPB
+function. The valid return values are:
+
+=============		===============================
+LAPB_OK			LAPB unregistered successfully.
+LAPB_BADTOKEN		Invalid/unknown LAPB token.
+=============		===============================
+
+::
+
+    int lapb_getparms(void *token, struct lapb_parms_struct *parms);
+
+This allows the device driver to get the values of the current LAPB
+variables, the lapb_parms_struct is described above. The valid return values
+are:
+
+=============		=============================
+LAPB_OK			LAPB getparms was successful.
+LAPB_BADTOKEN		Invalid/unknown LAPB token.
+=============		=============================
+
+::
+
+    int lapb_setparms(void *token, struct lapb_parms_struct *parms);
+
+This allows the device driver to set the values of the current LAPB
+variables, the lapb_parms_struct is described above. The values of t1timer,
+t2timer and n2count are ignored, likewise changing the mode bits when
+connected will be ignored. An error implies that none of the values have
+been changed. The valid return values are:
+
+=============		=================================================
+LAPB_OK			LAPB getparms was successful.
+LAPB_BADTOKEN		Invalid/unknown LAPB token.
+LAPB_INVALUE		One of the values was out of its allowable range.
+=============		=================================================
+
+::
+
+    int lapb_connect_request(void *token);
+
+Initiate a connect using the current parameter settings. The valid return
+values are:
+
+==============		=================================
+LAPB_OK			LAPB is starting to connect.
+LAPB_BADTOKEN		Invalid/unknown LAPB token.
+LAPB_CONNECTED		LAPB module is already connected.
+==============		=================================
+
+::
+
+    int lapb_disconnect_request(void *token);
+
+Initiate a disconnect. The valid return values are:
+
+=================	===============================
+LAPB_OK			LAPB is starting to disconnect.
+LAPB_BADTOKEN		Invalid/unknown LAPB token.
+LAPB_NOTCONNECTED	LAPB module is not connected.
+=================	===============================
+
+::
+
+    int lapb_data_request(void *token, struct sk_buff *skb);
+
+Queue data with the LAPB module for transmitting over the link. If the call
+is successful then the skbuff is owned by the LAPB module and may not be
+used by the device driver again. The valid return values are:
+
+=================	=============================
+LAPB_OK			LAPB has accepted the data.
+LAPB_BADTOKEN		Invalid/unknown LAPB token.
+LAPB_NOTCONNECTED	LAPB module is not connected.
+=================	=============================
+
+::
+
+    int lapb_data_received(void *token, struct sk_buff *skb);
+
+Queue data with the LAPB module which has been received from the device. It
+is expected that the data passed to the LAPB module has skb->data pointing
+to the beginning of the LAPB data. If the call is successful then the skbuff
+is owned by the LAPB module and may not be used by the device driver again.
+The valid return values are:
+
+=============		===========================
+LAPB_OK			LAPB has accepted the data.
+LAPB_BADTOKEN		Invalid/unknown LAPB token.
+=============		===========================
+
+Callbacks
+---------
+
+These callbacks are functions provided by the device driver for the LAPB
+module to call when an event occurs. They are registered with the LAPB
+module with lapb_register (see above) in the structure lapb_register_struct
+(see above).
+
+::
+
+    void (*connect_confirmation)(void *token, int reason);
+
+This is called by the LAPB module when a connection is established after
+being requested by a call to lapb_connect_request (see above). The reason is
+always LAPB_OK.
+
+::
+
+    void (*connect_indication)(void *token, int reason);
+
+This is called by the LAPB module when the link is established by the remote
+system. The value of reason is always LAPB_OK.
+
+::
+
+    void (*disconnect_confirmation)(void *token, int reason);
+
+This is called by the LAPB module when an event occurs after the device
+driver has called lapb_disconnect_request (see above). The reason indicates
+what has happened. In all cases the LAPB link can be regarded as being
+terminated. The values for reason are:
+
+=================	====================================================
+LAPB_OK			The LAPB link was terminated normally.
+LAPB_NOTCONNECTED	The remote system was not connected.
+LAPB_TIMEDOUT		No response was received in N2 tries from the remote
+			system.
+=================	====================================================
+
+::
+
+    void (*disconnect_indication)(void *token, int reason);
+
+This is called by the LAPB module when the link is terminated by the remote
+system or another event has occurred to terminate the link. This may be
+returned in response to a lapb_connect_request (see above) if the remote
+system refused the request. The values for reason are:
+
+=================	====================================================
+LAPB_OK			The LAPB link was terminated normally by the remote
+			system.
+LAPB_REFUSED		The remote system refused the connect request.
+LAPB_NOTCONNECTED	The remote system was not connected.
+LAPB_TIMEDOUT		No response was received in N2 tries from the remote
+			system.
+=================	====================================================
+
+::
+
+    int (*data_indication)(void *token, struct sk_buff *skb);
+
+This is called by the LAPB module when data has been received from the
+remote system that should be passed onto the next layer in the protocol
+stack. The skbuff becomes the property of the device driver and the LAPB
+module will not perform any more actions on it. The skb->data pointer will
+be pointing to the first byte of data after the LAPB header.
+
+This method should return NET_RX_DROP (as defined in the header
+file include/linux/netdevice.h) if and only if the frame was dropped
+before it could be delivered to the upper layer.
+
+::
+
+    void (*data_transmit)(void *token, struct sk_buff *skb);
+
+This is called by the LAPB module when data is to be transmitted to the
+remote system by the device driver. The skbuff becomes the property of the
+device driver and the LAPB module will not perform any more actions on it.
+The skb->data pointer will be pointing to the first byte of the LAPB header.