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, 242 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-mtd b/Documentation/ABI/testing/sysfs-class-mtd
new file mode 100644
index 000000000..f77fa4f6d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-mtd
@@ -0,0 +1,242 @@
+What:		/sys/class/mtd/
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		The mtd/ class subdirectory belongs to the MTD subsystem
+		(MTD core).
+
+What:		/sys/class/mtd/mtdX/
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		The /sys/class/mtd/mtd{0,1,2,3,...} directories correspond
+		to each /dev/mtdX character device.  These may represent
+		physical/simulated flash devices, partitions on a flash
+		device, or concatenated flash devices.
+
+What:		/sys/class/mtd/mtdXro/
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		These directories provide the corresponding read-only device
+		nodes for /sys/class/mtd/mtdX/ .
+
+What:		/sys/class/mtd/mtdX/dev
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		Major and minor numbers of the character device corresponding
+		to this MTD device (in <major>:<minor> format).  This is the
+		read-write device so <minor> will be even.
+
+What:		/sys/class/mtd/mtdXro/dev
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		Major and minor numbers of the character device corresponding
+		to the read-only variant of the MTD device (in
+		<major>:<minor> format).  In this case <minor> will be odd.
+
+What:		/sys/class/mtd/mtdX/erasesize
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		"Major" erase size for the device.  If numeraseregions is
+		zero, this is the eraseblock size for the entire device.
+		Otherwise, the MEMGETREGIONCOUNT/MEMGETREGIONINFO ioctls
+		can be used to determine the actual eraseblock layout.
+
+What:		/sys/class/mtd/mtdX/flags
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		A hexadecimal value representing the device flags, ORed
+		together:
+
+		0x0400: MTD_WRITEABLE - device is writable
+		0x0800: MTD_BIT_WRITEABLE - single bits can be flipped
+		0x1000: MTD_NO_ERASE - no erase necessary
+		0x2000: MTD_POWERUP_LOCK - always locked after reset
+
+What:		/sys/class/mtd/mtdX/name
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		A human-readable ASCII name for the device or partition.
+		This will match the name in /proc/mtd .
+
+What:		/sys/class/mtd/mtdX/numeraseregions
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		For devices that have variable eraseblock sizes, this
+		provides the total number of erase regions.  Otherwise,
+		it will read back as zero.
+
+What:		/sys/class/mtd/mtdX/oobsize
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		Number of OOB bytes per page.
+
+What:		/sys/class/mtd/mtdX/size
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		Total size of the device/partition, in bytes.
+
+What:		/sys/class/mtd/mtdX/type
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		One of the following ASCII strings, representing the device
+		type:
+
+		absent, ram, rom, nor, nand, mlc-nand, dataflash, ubi, unknown
+
+What:		/sys/class/mtd/mtdX/writesize
+Date:		April 2009
+KernelVersion:	2.6.29
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		Minimal writable flash unit size.  This will always be
+		a positive integer.
+
+		In the case of NOR flash it is 1 (even though individual
+		bits can be cleared).
+
+		In the case of NAND flash it is one NAND page (or a
+		half page, or a quarter page).
+
+		In the case of ECC NOR, it is the ECC block size.
+
+What:		/sys/class/mtd/mtdX/ecc_strength
+Date:		April 2012
+KernelVersion:	3.4
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		Maximum number of bit errors that the device is capable of
+		correcting within each region covering an ECC step (see
+		ecc_step_size).  This will always be a non-negative integer.
+
+		In the case of devices lacking any ECC capability, it is 0.
+
+What:		/sys/class/mtd/mtdX/bitflip_threshold
+Date:		April 2012
+KernelVersion:	3.4
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		This allows the user to examine and adjust the criteria by which
+		mtd returns -EUCLEAN from mtd_read() and mtd_read_oob().  If the
+		maximum number of bit errors that were corrected on any single
+		region comprising an ecc step (as reported by the driver) equals
+		or exceeds this value, -EUCLEAN is returned.  Otherwise, absent
+		an error, 0 is returned.  Higher layers (e.g., UBI) use this
+		return code as an indication that an erase block may be
+		degrading and should be scrutinized as a candidate for being
+		marked as bad.
+
+		The initial value may be specified by the flash device driver.
+		If not, then the default value is ecc_strength.
+
+		The introduction of this feature brings a subtle change to the
+		meaning of the -EUCLEAN return code.  Previously, it was
+		interpreted to mean simply "one or more bit errors were
+		corrected".  Its new interpretation can be phrased as "a
+		dangerously high number of bit errors were corrected on one or
+		more regions comprising an ecc step".  The precise definition of
+		"dangerously high" can be adjusted by the user with
+		bitflip_threshold.  Users are discouraged from doing this,
+		however, unless they know what they are doing and have intimate
+		knowledge of the properties of their device.  Broadly speaking,
+		bitflip_threshold should be low enough to detect genuine erase
+		block degradation, but high enough to avoid the consequences of
+		a persistent return value of -EUCLEAN on devices where sticky
+		bitflips occur.  Note that if bitflip_threshold exceeds
+		ecc_strength, -EUCLEAN is never returned by the read operations.
+		Conversely, if bitflip_threshold is zero, -EUCLEAN is always
+		returned, absent a hard error.
+
+		This is generally applicable only to NAND flash devices with ECC
+		capability.  It is ignored on devices lacking ECC capability;
+		i.e., devices for which ecc_strength is zero.
+
+What:		/sys/class/mtd/mtdX/ecc_step_size
+Date:		May 2013
+KernelVersion:	3.10
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		The size of a single region covered by ECC, known as the ECC
+		step.  Devices may have several equally sized ECC steps within
+		each writesize region.
+
+		It will always be a non-negative integer.  In the case of
+		devices lacking any ECC capability, it is 0.
+
+What:		/sys/class/mtd/mtdX/ecc_failures
+Date:		June 2014
+KernelVersion:	3.17
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		The number of failures reported by this device's ECC. Typically,
+		these failures are associated with failed read operations.
+
+		It will always be a non-negative integer.  In the case of
+		devices lacking any ECC capability, it is 0.
+
+What:		/sys/class/mtd/mtdX/corrected_bits
+Date:		June 2014
+KernelVersion:	3.17
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		The number of bits that have been corrected by means of the
+		device's ECC.
+
+		It will always be a non-negative integer.  In the case of
+		devices lacking any ECC capability, it is 0.
+
+What:		/sys/class/mtd/mtdX/bad_blocks
+Date:		June 2014
+KernelVersion:	3.17
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		The number of blocks marked as bad, if any, in this partition.
+
+What:		/sys/class/mtd/mtdX/bbt_blocks
+Date:		June 2014
+KernelVersion:	3.17
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		The number of blocks that are marked as reserved, if any, in
+		this partition. These are typically used to store the in-flash
+		bad block table (BBT).
+
+What:		/sys/class/mtd/mtdX/offset
+Date:		March 2015
+KernelVersion:	4.1
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		For a partition, the offset of that partition from the start
+		of the parent (another partition or a flash device) in bytes.
+		This attribute is absent on flash devices, so it can be used
+		to distinguish them from partitions.
+
+What:		/sys/class/mtd/mtdX/oobavail
+Date:		April 2018
+KernelVersion:	4.16
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		Number of bytes available for a client to place data into
+		the out of band area.