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, 150 insertions, 0 deletions

diff --git a/Documentation/admin-guide/aoe/aoe.rst b/Documentation/admin-guide/aoe/aoe.rst
new file mode 100644
index 000000000..a05e75136
--- /dev/null
+++ b/Documentation/admin-guide/aoe/aoe.rst
@@ -0,0 +1,150 @@
+Introduction
+============
+
+ATA over Ethernet is a network protocol that provides simple access to
+block storage on the LAN.
+
+  http://support.coraid.com/documents/AoEr11.txt
+
+The EtherDrive (R) HOWTO for 2.6 and 3.x kernels is found at ...
+
+  http://support.coraid.com/support/linux/EtherDrive-2.6-HOWTO.html
+
+It has many tips and hints!  Please see, especially, recommended
+tunings for virtual memory:
+
+  http://support.coraid.com/support/linux/EtherDrive-2.6-HOWTO-5.html#ss5.19
+
+The aoetools are userland programs that are designed to work with this
+driver.  The aoetools are on sourceforge.
+
+  http://aoetools.sourceforge.net/
+
+The scripts in this Documentation/admin-guide/aoe directory are intended to
+document the use of the driver and are not necessary if you install
+the aoetools.
+
+
+Creating Device Nodes
+=====================
+
+  Users of udev should find the block device nodes created
+  automatically, but to create all the necessary device nodes, use the
+  udev configuration rules provided in udev.txt (in this directory).
+
+  There is a udev-install.sh script that shows how to install these
+  rules on your system.
+
+  There is also an autoload script that shows how to edit
+  /etc/modprobe.d/aoe.conf to ensure that the aoe module is loaded when
+  necessary.  Preloading the aoe module is preferable to autoloading,
+  however, because AoE discovery takes a few seconds.  It can be
+  confusing when an AoE device is not present the first time the a
+  command is run but appears a second later.
+
+Using Device Nodes
+==================
+
+  "cat /dev/etherd/err" blocks, waiting for error diagnostic output,
+  like any retransmitted packets.
+
+  "echo eth2 eth4 > /dev/etherd/interfaces" tells the aoe driver to
+  limit ATA over Ethernet traffic to eth2 and eth4.  AoE traffic from
+  untrusted networks should be ignored as a matter of security.  See
+  also the aoe_iflist driver option described below.
+
+  "echo > /dev/etherd/discover" tells the driver to find out what AoE
+  devices are available.
+
+  In the future these character devices may disappear and be replaced
+  by sysfs counterparts.  Using the commands in aoetools insulates
+  users from these implementation details.
+
+  The block devices are named like this::
+
+	e{shelf}.{slot}
+	e{shelf}.{slot}p{part}
+
+  ... so that "e0.2" is the third blade from the left (slot 2) in the
+  first shelf (shelf address zero).  That's the whole disk.  The first
+  partition on that disk would be "e0.2p1".
+
+Using sysfs
+===========
+
+  Each aoe block device in /sys/block has the extra attributes of
+  state, mac, and netif.  The state attribute is "up" when the device
+  is ready for I/O and "down" if detected but unusable.  The
+  "down,closewait" state shows that the device is still open and
+  cannot come up again until it has been closed.
+
+  The mac attribute is the ethernet address of the remote AoE device.
+  The netif attribute is the network interface on the localhost
+  through which we are communicating with the remote AoE device.
+
+  There is a script in this directory that formats this information in
+  a convenient way.  Users with aoetools should use the aoe-stat
+  command::
+
+    root@makki root# sh Documentation/admin-guide/aoe/status.sh
+       e10.0            eth3              up
+       e10.1            eth3              up
+       e10.2            eth3              up
+       e10.3            eth3              up
+       e10.4            eth3              up
+       e10.5            eth3              up
+       e10.6            eth3              up
+       e10.7            eth3              up
+       e10.8            eth3              up
+       e10.9            eth3              up
+        e4.0            eth1              up
+        e4.1            eth1              up
+        e4.2            eth1              up
+        e4.3            eth1              up
+        e4.4            eth1              up
+        e4.5            eth1              up
+        e4.6            eth1              up
+        e4.7            eth1              up
+        e4.8            eth1              up
+        e4.9            eth1              up
+
+  Use /sys/module/aoe/parameters/aoe_iflist (or better, the driver
+  option discussed below) instead of /dev/etherd/interfaces to limit
+  AoE traffic to the network interfaces in the given
+  whitespace-separated list.  Unlike the old character device, the
+  sysfs entry can be read from as well as written to.
+
+  It's helpful to trigger discovery after setting the list of allowed
+  interfaces.  The aoetools package provides an aoe-discover script
+  for this purpose.  You can also directly use the
+  /dev/etherd/discover special file described above.
+
+Driver Options
+==============
+
+  There is a boot option for the built-in aoe driver and a
+  corresponding module parameter, aoe_iflist.  Without this option,
+  all network interfaces may be used for ATA over Ethernet.  Here is a
+  usage example for the module parameter::
+
+    modprobe aoe_iflist="eth1 eth3"
+
+  The aoe_deadsecs module parameter determines the maximum number of
+  seconds that the driver will wait for an AoE device to provide a
+  response to an AoE command.  After aoe_deadsecs seconds have
+  elapsed, the AoE device will be marked as "down".  A value of zero
+  is supported for testing purposes and makes the aoe driver keep
+  trying AoE commands forever.
+
+  The aoe_maxout module parameter has a default of 128.  This is the
+  maximum number of unresponded packets that will be sent to an AoE
+  target at one time.
+
+  The aoe_dyndevs module parameter defaults to 1, meaning that the
+  driver will assign a block device minor number to a discovered AoE
+  target based on the order of its discovery.  With dynamic minor
+  device numbers in use, a greater range of AoE shelf and slot
+  addresses can be supported.  Users with udev will never have to
+  think about minor numbers.  Using aoe_dyndevs=0 allows device nodes
+  to be pre-created using a static minor-number scheme with the
+  aoe-mkshelf script in the aoetools.