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, 255 insertions, 0 deletions

diff --git a/Documentation/admin-guide/blockdev/floppy.rst b/Documentation/admin-guide/blockdev/floppy.rst
new file mode 100644
index 000000000..0328438eb
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/floppy.rst
@@ -0,0 +1,255 @@
+=============
+Floppy Driver
+=============
+
+FAQ list:
+=========
+
+A FAQ list may be found in the fdutils package (see below), and also
+at <https://fdutils.linux.lu/faq.html>.
+
+
+LILO configuration options (Thinkpad users, read this)
+======================================================
+
+The floppy driver is configured using the 'floppy=' option in
+lilo. This option can be typed at the boot prompt, or entered in the
+lilo configuration file.
+
+Example: If your kernel is called linux-2.6.9, type the following line
+at the lilo boot prompt (if you have a thinkpad)::
+
+ linux-2.6.9 floppy=thinkpad
+
+You may also enter the following line in /etc/lilo.conf, in the description
+of linux-2.6.9::
+
+ append = "floppy=thinkpad"
+
+Several floppy related options may be given, example::
+
+ linux-2.6.9 floppy=daring floppy=two_fdc
+ append = "floppy=daring floppy=two_fdc"
+
+If you give options both in the lilo config file and on the boot
+prompt, the option strings of both places are concatenated, the boot
+prompt options coming last. That's why there are also options to
+restore the default behavior.
+
+
+Module configuration options
+============================
+
+If you use the floppy driver as a module, use the following syntax::
+
+	modprobe floppy floppy="<options>"
+
+Example::
+
+	modprobe floppy floppy="omnibook messages"
+
+If you need certain options enabled every time you load the floppy driver,
+you can put::
+
+	options floppy floppy="omnibook messages"
+
+in a configuration file in /etc/modprobe.d/.
+
+
+The floppy driver related options are:
+
+ floppy=asus_pci
+	Sets the bit mask to allow only units 0 and 1. (default)
+
+ floppy=daring
+	Tells the floppy driver that you have a well behaved floppy controller.
+	This allows more efficient and smoother operation, but may fail on
+	certain controllers. This may speed up certain operations.
+
+ floppy=0,daring
+	Tells the floppy driver that your floppy controller should be used
+	with caution.
+
+ floppy=one_fdc
+	Tells the floppy driver that you have only one floppy controller.
+	(default)
+
+ floppy=two_fdc / floppy=<address>,two_fdc
+	Tells the floppy driver that you have two floppy controllers.
+	The second floppy controller is assumed to be at <address>.
+	This option is not needed if the second controller is at address
+	0x370, and if you use the 'cmos' option.
+
+ floppy=thinkpad
+	Tells the floppy driver that you have a Thinkpad. Thinkpads use an
+	inverted convention for the disk change line.
+
+ floppy=0,thinkpad
+	Tells the floppy driver that you don't have a Thinkpad.
+
+ floppy=omnibook / floppy=nodma
+	Tells the floppy driver not to use Dma for data transfers.
+	This is needed on HP Omnibooks, which don't have a workable
+	DMA channel for the floppy driver. This option is also useful
+	if you frequently get "Unable to allocate DMA memory" messages.
+	Indeed, dma memory needs to be continuous in physical memory,
+	and is thus harder to find, whereas non-dma buffers may be
+	allocated in virtual memory. However, I advise against this if
+	you have an FDC without a FIFO (8272A or 82072). 82072A and
+	later are OK. You also need at least a 486 to use nodma.
+	If you use nodma mode, I suggest you also set the FIFO
+	threshold to 10 or lower, in order to limit the number of data
+	transfer interrupts.
+
+	If you have a FIFO-able FDC, the floppy driver automatically
+	falls back on non DMA mode if no DMA-able memory can be found.
+	If you want to avoid this, explicitly ask for 'yesdma'.
+
+ floppy=yesdma
+	Tells the floppy driver that a workable DMA channel is available.
+	(default)
+
+ floppy=nofifo
+	Disables the FIFO entirely. This is needed if you get "Bus
+	master arbitration error" messages from your Ethernet card (or
+	from other devices) while accessing the floppy.
+
+ floppy=usefifo
+	Enables the FIFO. (default)
+
+ floppy=<threshold>,fifo_depth
+	Sets the FIFO threshold. This is mostly relevant in DMA
+	mode. If this is higher, the floppy driver tolerates more
+	interrupt latency, but it triggers more interrupts (i.e. it
+	imposes more load on the rest of the system). If this is
+	lower, the interrupt latency should be lower too (faster
+	processor). The benefit of a lower threshold is less
+	interrupts.
+
+	To tune the fifo threshold, switch on over/underrun messages
+	using 'floppycontrol --messages'. Then access a floppy
+	disk. If you get a huge amount of "Over/Underrun - retrying"
+	messages, then the fifo threshold is too low. Try with a
+	higher value, until you only get an occasional Over/Underrun.
+	It is a good idea to compile the floppy driver as a module
+	when doing this tuning. Indeed, it allows to try different
+	fifo values without rebooting the machine for each test. Note
+	that you need to do 'floppycontrol --messages' every time you
+	re-insert the module.
+
+	Usually, tuning the fifo threshold should not be needed, as
+	the default (0xa) is reasonable.
+
+ floppy=<drive>,<type>,cmos
+	Sets the CMOS type of <drive> to <type>. This is mandatory if
+	you have more than two floppy drives (only two can be
+	described in the physical CMOS), or if your BIOS uses
+	non-standard CMOS types. The CMOS types are:
+
+	       ==  ==================================
+		0  Use the value of the physical CMOS
+		1  5 1/4 DD
+		2  5 1/4 HD
+		3  3 1/2 DD
+		4  3 1/2 HD
+		5  3 1/2 ED
+		6  3 1/2 ED
+	       16  unknown or not installed
+	       ==  ==================================
+
+	(Note: there are two valid types for ED drives. This is because 5 was
+	initially chosen to represent floppy *tapes*, and 6 for ED drives.
+	AMI ignored this, and used 5 for ED drives. That's why the floppy
+	driver handles both.)
+
+ floppy=unexpected_interrupts
+	Print a warning message when an unexpected interrupt is received.
+	(default)
+
+ floppy=no_unexpected_interrupts / floppy=L40SX
+	Don't print a message when an unexpected interrupt is received. This
+	is needed on IBM L40SX laptops in certain video modes. (There seems
+	to be an interaction between video and floppy. The unexpected
+	interrupts affect only performance, and can be safely ignored.)
+
+ floppy=broken_dcl
+	Don't use the disk change line, but assume that the disk was
+	changed whenever the device node is reopened. Needed on some
+	boxes where the disk change line is broken or unsupported.
+	This should be regarded as a stopgap measure, indeed it makes
+	floppy operation less efficient due to unneeded cache
+	flushings, and slightly more unreliable. Please verify your
+	cable, connection and jumper settings if you have any DCL
+	problems. However, some older drives, and also some laptops
+	are known not to have a DCL.
+
+ floppy=debug
+	Print debugging messages.
+
+ floppy=messages
+	Print informational messages for some operations (disk change
+	notifications, warnings about over and underruns, and about
+	autodetection).
+
+ floppy=silent_dcl_clear
+	Uses a less noisy way to clear the disk change line (which
+	doesn't involve seeks). Implied by 'daring' option.
+
+ floppy=<nr>,irq
+	Sets the floppy IRQ to <nr> instead of 6.
+
+ floppy=<nr>,dma
+	Sets the floppy DMA channel to <nr> instead of 2.
+
+ floppy=slow
+	Use PS/2 stepping rate::
+
+	   PS/2 floppies have much slower step rates than regular floppies.
+	   It's been recommended that take about 1/4 of the default speed
+	   in some more extreme cases.
+
+
+Supporting utilities and additional documentation:
+==================================================
+
+Additional parameters of the floppy driver can be configured at
+runtime. Utilities which do this can be found in the fdutils package.
+This package also contains a new version of mtools which allows to
+access high capacity disks (up to 1992K on a high density 3 1/2 disk!).
+It also contains additional documentation about the floppy driver.
+
+The latest version can be found at fdutils homepage:
+
+ https://fdutils.linux.lu
+
+The fdutils releases can be found at:
+
+ https://fdutils.linux.lu/download.html
+
+ http://www.tux.org/pub/knaff/fdutils/
+
+ ftp://metalab.unc.edu/pub/Linux/utils/disk-management/
+
+Reporting problems about the floppy driver
+==========================================
+
+If you have a question or a bug report about the floppy driver, mail
+me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use
+comp.os.linux.hardware. As the volume in these groups is rather high,
+be sure to include the word "floppy" (or "FLOPPY") in the subject
+line.  If the reported problem happens when mounting floppy disks, be
+sure to mention also the type of the filesystem in the subject line.
+
+Be sure to read the FAQ before mailing/posting any bug reports!
+
+Alain
+
+Changelog
+=========
+
+10-30-2004 :
+		Cleanup, updating, add reference to module configuration.
+		James Nelson <james4765@gmail.com>
+
+6-3-2000 :
+		Original Document