tree d060266252fcf0dd8fbb399d6c3f26aab6be756e
parent ccfe9e42e451232dd17a230d1b4e979c3d15311e
author Steven Rostedt (Red Hat) <rostedt@goodmis.org> 1377925447 -0400
committer Steven Rostedt <rostedt@goodmis.org> 1378251386 -0400

ftrace: Fix a slight race in modifying what function callback gets traced

There's a slight race when going from a list function to a non list
function. That is, when only one callback is registered to the function
tracer, it gets called directly by the mcount trampoline. But if this
function has filters, it may be called by the wrong functions.

As the list ops callback that handles multiple callbacks that are
registered to ftrace, it also handles what functions they call. While
the transaction is taking place, use the list function always, and
after all the updates are finished (only the functions that should be
traced are being traced), then we can update the trampoline to call
the function directly.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>