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, 250 insertions, 0 deletions

diff --git a/Documentation/filesystems/affs.rst b/Documentation/filesystems/affs.rst
new file mode 100644
index 000000000..5776cbd5f
--- /dev/null
+++ b/Documentation/filesystems/affs.rst
@@ -0,0 +1,250 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============================
+Overview of Amiga Filesystems
+=============================
+
+Not all varieties of the Amiga filesystems are supported for reading and
+writing. The Amiga currently knows six different filesystems:
+
+==============	===============================================================
+DOS\0		The old or original filesystem, not really suited for
+		hard disks and normally not used on them, either.
+		Supported read/write.
+
+DOS\1		The original Fast File System. Supported read/write.
+
+DOS\2		The old "international" filesystem. International means that
+		a bug has been fixed so that accented ("international") letters
+		in file names are case-insensitive, as they ought to be.
+		Supported read/write.
+
+DOS\3		The "international" Fast File System.  Supported read/write.
+
+DOS\4		The original filesystem with directory cache. The directory
+		cache speeds up directory accesses on floppies considerably,
+		but slows down file creation/deletion. Doesn't make much
+		sense on hard disks. Supported read only.
+
+DOS\5		The Fast File System with directory cache. Supported read only.
+==============	===============================================================
+
+All of the above filesystems allow block sizes from 512 to 32K bytes.
+Supported block sizes are: 512, 1024, 2048 and 4096 bytes. Larger blocks
+speed up almost everything at the expense of wasted disk space. The speed
+gain above 4K seems not really worth the price, so you don't lose too
+much here, either.
+
+The muFS (multi user File System) equivalents of the above file systems
+are supported, too.
+
+Mount options for the AFFS
+==========================
+
+protect
+		If this option is set, the protection bits cannot be altered.
+
+setuid[=uid]
+		This sets the owner of all files and directories in the file
+		system to uid or the uid of the current user, respectively.
+
+setgid[=gid]
+		Same as above, but for gid.
+
+mode=mode
+		Sets the mode flags to the given (octal) value, regardless
+		of the original permissions. Directories will get an x
+		permission if the corresponding r bit is set.
+		This is useful since most of the plain AmigaOS files
+		will map to 600.
+
+nofilenametruncate
+		The file system will return an error when filename exceeds
+		standard maximum filename length (30 characters).
+
+reserved=num
+		Sets the number of reserved blocks at the start of the
+		partition to num. You should never need this option.
+		Default is 2.
+
+root=block
+		Sets the block number of the root block. This should never
+		be necessary.
+
+bs=blksize
+		Sets the blocksize to blksize. Valid block sizes are 512,
+		1024, 2048 and 4096. Like the root option, this should
+		never be necessary, as the affs can figure it out itself.
+
+quiet
+		The file system will not return an error for disallowed
+		mode changes.
+
+verbose
+		The volume name, file system type and block size will
+		be written to the syslog when the filesystem is mounted.
+
+mufs
+		The filesystem is really a muFS, also it doesn't
+		identify itself as one. This option is necessary if
+		the filesystem wasn't formatted as muFS, but is used
+		as one.
+
+prefix=path
+		Path will be prefixed to every absolute path name of
+		symbolic links on an AFFS partition. Default = "/".
+		(See below.)
+
+volume=name
+		When symbolic links with an absolute path are created
+		on an AFFS partition, name will be prepended as the
+		volume name. Default = "" (empty string).
+		(See below.)
+
+Handling of the Users/Groups and protection flags
+=================================================
+
+Amiga -> Linux:
+
+The Amiga protection flags RWEDRWEDHSPARWED are handled as follows:
+
+  - R maps to r for user, group and others. On directories, R implies x.
+
+  - W maps to w.
+
+  - E maps to x.
+
+  - D is ignored.
+
+  - H, S and P are always retained and ignored under Linux.
+
+  - A is cleared when a file is written to.
+
+User id and group id will be used unless set[gu]id are given as mount
+options. Since most of the Amiga file systems are single user systems
+they will be owned by root. The root directory (the mount point) of the
+Amiga filesystem will be owned by the user who actually mounts the
+filesystem (the root directory doesn't have uid/gid fields).
+
+Linux -> Amiga:
+
+The Linux rwxrwxrwx file mode is handled as follows:
+
+  - r permission will allow R for user, group and others.
+
+  - w permission will allow W for user, group and others.
+
+  - x permission of the user will allow E for plain files.
+
+  - D will be allowed for user, group and others.
+
+  - All other flags (suid, sgid, ...) are ignored and will
+    not be retained.
+
+Newly created files and directories will get the user and group ID
+of the current user and a mode according to the umask.
+
+Symbolic links
+==============
+
+Although the Amiga and Linux file systems resemble each other, there
+are some, not always subtle, differences. One of them becomes apparent
+with symbolic links. While Linux has a file system with exactly one
+root directory, the Amiga has a separate root directory for each
+file system (for example, partition, floppy disk, ...). With the Amiga,
+these entities are called "volumes". They have symbolic names which
+can be used to access them. Thus, symbolic links can point to a
+different volume. AFFS turns the volume name into a directory name
+and prepends the prefix path (see prefix option) to it.
+
+Example:
+You mount all your Amiga partitions under /amiga/<volume> (where
+<volume> is the name of the volume), and you give the option
+"prefix=/amiga/" when mounting all your AFFS partitions. (They
+might be "User", "WB" and "Graphics", the mount points /amiga/User,
+/amiga/WB and /amiga/Graphics). A symbolic link referring to
+"User:sc/include/dos/dos.h" will be followed to
+"/amiga/User/sc/include/dos/dos.h".
+
+Examples
+========
+
+Command line::
+
+    mount  Archive/Amiga/Workbench3.1.adf /mnt -t affs -o loop,verbose
+    mount  /dev/sda3 /Amiga -t affs
+
+/etc/fstab entry::
+
+    /dev/sdb5	/amiga/Workbench    affs    noauto,user,exec,verbose 0 0
+
+IMPORTANT NOTE
+==============
+
+If you boot Windows 95 (don't know about 3.x, 98 and NT) while you
+have an Amiga harddisk connected to your PC, it will overwrite
+the bytes 0x00dc..0x00df of block 0 with garbage, thus invalidating
+the Rigid Disk Block. Sheer luck has it that this is an unused
+area of the RDB, so only the checksum doesn't match anymore.
+Linux will ignore this garbage and recognize the RDB anyway, but
+before you connect that drive to your Amiga again, you must
+restore or repair your RDB. So please do make a backup copy of it
+before booting Windows!
+
+If the damage is already done, the following should fix the RDB
+(where <disk> is the device name).
+
+DO AT YOUR OWN RISK::
+
+  dd if=/dev/<disk> of=rdb.tmp count=1
+  cp rdb.tmp rdb.fixed
+  dd if=/dev/zero of=rdb.fixed bs=1 seek=220 count=4
+  dd if=rdb.fixed of=/dev/<disk>
+
+Bugs, Restrictions, Caveats
+===========================
+
+Quite a few things may not work as advertised. Not everything is
+tested, though several hundred MB have been read and written using
+this fs. For a most up-to-date list of bugs please consult
+fs/affs/Changes.
+
+By default, filenames are truncated to 30 characters without warning.
+'nofilenametruncate' mount option can change that behavior.
+
+Case is ignored by the affs in filename matching, but Linux shells
+do care about the case. Example (with /wb being an affs mounted fs)::
+
+    rm /wb/WRONGCASE
+
+will remove /mnt/wrongcase, but::
+
+    rm /wb/WR*
+
+will not since the names are matched by the shell.
+
+The block allocation is designed for hard disk partitions. If more
+than 1 process writes to a (small) diskette, the blocks are allocated
+in an ugly way (but the real AFFS doesn't do much better). This
+is also true when space gets tight.
+
+You cannot execute programs on an OFS (Old File System), since the
+program files cannot be memory mapped due to the 488 byte blocks.
+For the same reason you cannot mount an image on such a filesystem
+via the loopback device.
+
+The bitmap valid flag in the root block may not be accurate when the
+system crashes while an affs partition is mounted. There's currently
+no way to fix a garbled filesystem without an Amiga (disk validator)
+or manually (who would do this?). Maybe later.
+
+If you mount affs partitions on system startup, you may want to tell
+fsck that the fs should not be checked (place a '0' in the sixth field
+of /etc/fstab).
+
+It's not possible to read floppy disks with a normal PC or workstation
+due to an incompatibility with the Amiga floppy controller.
+
+If you are interested in an Amiga Emulator for Linux, look at
+
+http://web.archive.org/web/%2E/http://www.freiburg.linux.de/~uae/