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, 178 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-mic b/Documentation/ABI/testing/sysfs-class-mic
new file mode 100644
index 000000000..5e5f36d10
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-mic
@@ -0,0 +1,178 @@
+What:		/sys/class/mic/
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		The mic class directory belongs to Intel MIC devices and
+		provides information per MIC device. An Intel MIC device is a
+		PCIe form factor add-in Coprocessor card based on the Intel Many
+		Integrated Core (MIC) architecture that runs a Linux OS.
+
+What:		/sys/class/mic/mic<X>
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		The directories /sys/class/mic/mic0, /sys/class/mic/mic1 etc.,
+		represent MIC devices (0,1,..etc). Each directory has
+		information specific to that MIC device.
+
+What:		/sys/class/mic/mic<X>/family
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		Provides information about the Coprocessor family for an Intel
+		MIC device. For example - "x100"
+
+What:		/sys/class/mic/mic<X>/stepping
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		Provides information about the silicon stepping for an Intel
+		MIC device. For example - "A0" or "B0"
+
+What:		/sys/class/mic/mic<X>/state
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		When read, this entry provides the current state of an Intel
+		MIC device in the context of the card OS. Possible values that
+		will be read are:
+
+
+		===============  ===============================================
+		"ready"		 The MIC device is ready to boot the card OS.
+				 On reading this entry after an OSPM resume,
+				 a "boot" has to be written to this entry if
+				 the card was previously shutdown during OSPM
+				 suspend.
+		"booting"	 The MIC device has initiated booting a card OS.
+		"online"	 The MIC device has completed boot and is online
+		"shutting_down"	 The card OS is shutting down.
+		"resetting"	 A reset has been initiated for the MIC device
+		"reset_failed"	 The MIC device has failed to reset.
+		===============  ===============================================
+
+		When written, this sysfs entry triggers different state change
+		operations depending upon the current state of the card OS.
+		Acceptable values are:
+
+
+		==========  ===================================================
+		"boot"      Boot the card OS image specified by the combination
+			    of firmware, ramdisk, cmdline and bootmode
+			    sysfs entries.
+		"reset"     Initiates device reset.
+		"shutdown"  Initiates card OS shutdown.
+		==========  ===================================================
+
+What:		/sys/class/mic/mic<X>/shutdown_status
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		An Intel MIC device runs a Linux OS during its operation. This
+		OS can shutdown because of various reasons. When read, this
+		entry provides the status on why the card OS was shutdown.
+		Possible values are:
+
+		==========  ===================================================
+		"nop"       shutdown status is not applicable, when the card OS
+			    is "online"
+		"crashed"   Shutdown because of a HW or SW crash.
+		"halted"    Shutdown because of a halt command.
+		"poweroff"  Shutdown because of a poweroff command.
+		"restart"   Shutdown because of a restart command.
+		==========  ===================================================
+
+What:		/sys/class/mic/mic<X>/cmdline
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		An Intel MIC device runs a Linux OS during its operation. Before
+		booting this card OS, it is possible to pass kernel command line
+		options to configure various features in it, similar to
+		self-bootable machines. When read, this entry provides
+		information about the current kernel command line options set to
+		boot the card OS. This entry can be written to change the
+		existing kernel command line options. Typically, the user would
+		want to read the current command line options, append new ones
+		or modify existing ones and then write the whole kernel command
+		line back to this entry.
+
+What:		/sys/class/mic/mic<X>/firmware
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		When read, this sysfs entry provides the path name under
+		/lib/firmware/ where the firmware image to be booted on the
+		card can be found. The entry can be written to change the
+		firmware image location under /lib/firmware/.
+
+What:		/sys/class/mic/mic<X>/ramdisk
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		When read, this sysfs entry provides the path name under
+		/lib/firmware/ where the ramdisk image to be used during card
+		OS boot can be found. The entry can be written to change
+		the ramdisk image location under /lib/firmware/.
+
+What:		/sys/class/mic/mic<X>/bootmode
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		When read, this sysfs entry provides the current bootmode for
+		the card. This sysfs entry can be written with the following
+		valid strings:
+		a) linux - Boot a Linux image.
+		b) flash - Boot an image for flash updates.
+
+What:		/sys/class/mic/mic<X>/log_buf_addr
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		An Intel MIC device runs a Linux OS during its operation. For
+		debugging purpose and early kernel boot messages, the user can
+		access the card OS log buffer via debugfs. When read, this entry
+		provides the kernel virtual address of the buffer where the card
+		OS log buffer can be read. This entry is written by the host
+		configuration daemon to set the log buffer address. The correct
+		log buffer address to be written can be found in the System.map
+		file of the card OS.
+
+What:		/sys/class/mic/mic<X>/log_buf_len
+Date:		October 2013
+KernelVersion:	3.13
+Contact:	Sudeep Dutt <sudeep.dutt@intel.com>
+Description:
+		An Intel MIC device runs a Linux OS during its operation. For
+		debugging purpose and early kernel boot messages, the user can
+		access the card OS log buffer via debugfs. When read, this entry
+		provides the kernel virtual address where the card OS log buffer
+		length can be read. This entry is written by host configuration
+		daemon to set the log buffer length address. The correct log
+		buffer length address to be written can be found in the
+		System.map file of the card OS.
+
+What:		/sys/class/mic/mic<X>/heartbeat_enable
+Date:		March 2015
+KernelVersion:	4.4
+Contact:	Ashutosh Dixit <ashutosh.dixit@intel.com>
+Description:
+		The MIC drivers detect and inform user space about card crashes
+		via a heartbeat mechanism (see the description of
+		shutdown_status above). User space can turn off this
+		notification by setting heartbeat_enable to 0 and enable it by
+		setting this entry to 1. If this notification is disabled it is
+		the responsibility of user space to detect card crashes via
+		alternative means such as a network ping. This setting is
+		enabled by default.