tracefs fixes for v7.1:

- Use list_add_tail_rcu() for walking eventfs children

  The children link list is protected by SRCU and list walkers can walk the
  list without the lock and only using SRCU. Using just list_add_tail() on
  weakly ordered architectures can cause issues. Instead use
  list_add_tail_rcu().

- Hold eventfs_mutex and SRCU for remount walk events

  The trace_apply_options() walks the tracefs_inodes where some are eventfs
  inodes and eventfs_remount() is called which in turn calls
  eventfs_set_attr(). This walk only holds normal RCU read locks, but the
  eventfs_mutex and SRCU should be held. Add a eventfs_remount_(un)lock()
  helpers to take the necessary locks before iterating the list.

  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
tracefs/fixes

Head SHA1: 07004a8c4b572171934390148ee48c4175c77eed


David Carlier (2):
      eventfs: Use list_add_tail_rcu() for SRCU-protected children list
      eventfs: Hold eventfs_mutex and SRCU when remount walks events

----
 fs/tracefs/event_inode.c | 16 +++++++++++++++-
 fs/tracefs/inode.c       |  5 ++++-
 fs/tracefs/internal.h    |  3 +++
 3 files changed, 22 insertions(+), 2 deletions(-)