tree 76e9363fd72afea51e6634fb38cc76e6d4be8767
parent ca321885b0511a85e2d1cd40caafedbeb18f4af6
parent 3ddee63a099ebbdc8f84697fe46730b58240c09d
author Linus Torvalds <torvalds@linux-foundation.org> 1413113239 -0400
committer Linus Torvalds <torvalds@linux-foundation.org> 1413113239 -0400
mergetag object 3ddee63a099ebbdc8f84697fe46730b58240c09d
 type commit
 tag trace-3.18
 tagger Steven Rostedt <rostedt@rostedt.homelinux.com> 1412630703 -0400
 
 This set has a few minor updates, but the big change is the redesign
 of the trampoline logic.
 
 The trampoline logic of 3.17 required a descriptor for every function
 that is registered to be traced and uses a trampoline. Currently,
 only the function graph tracer uses a trampoline, but if you were
 to trace all 32,000 (give or take a few thousand) functions with the
 function graph tracer, it would create 32,000 descriptors to let us
 know that there's a trampoline associated with it. This takes up a bit
 of memory when there's a better way to do it.
 
 The redesign now reuses the ftrace_ops' (what registers the function graph
 tracer) hash tables. The hash tables tell ftrace what the tracer
 wants to trace or doesn't want to trace. There's two of them: one
 that tells us what to trace, the other tells us what not to trace.
 If the first one is empty, it means all functions should be traced,
 otherwise only the ones that are listed should be. The second hash table
 tells us what not to trace, and if it is empty, all functions may be
 traced, and if there's any listed, then those should not be traced
 even if they exist in the first hash table.
 
 It took a bit of massaging, but now these hashes can be used to
 keep track of what has a trampoline and what does not, and allows
 the ftrace accounting to work. Now we can trace all functions when using
 the function graph trampoline, and avoid needing to create any special
 descriptors to hold all the functions that are being traced.
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Merge tag 'trace-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "This set has a few minor updates, but the big change is the redesign
  of the trampoline logic.

  The trampoline logic of 3.17 required a descriptor for every function
  that is registered to be traced and uses a trampoline.  Currently,
  only the function graph tracer uses a trampoline, but if you were to
  trace all 32,000 (give or take a few thousand) functions with the
  function graph tracer, it would create 32,000 descriptors to let us
  know that there's a trampoline associated with it.  This takes up a
  bit of memory when there's a better way to do it.

  The redesign now reuses the ftrace_ops' (what registers the function
  graph tracer) hash tables.  The hash tables tell ftrace what the
  tracer wants to trace or doesn't want to trace.  There's two of them:
  one that tells us what to trace, the other tells us what not to trace.
  If the first one is empty, it means all functions should be traced,
  otherwise only the ones that are listed should be.  The second hash
  table tells us what not to trace, and if it is empty, all functions
  may be traced, and if there's any listed, then those should not be
  traced even if they exist in the first hash table.

  It took a bit of massaging, but now these hashes can be used to keep
  track of what has a trampoline and what does not, and allows the
  ftrace accounting to work.  Now we can trace all functions when using
  the function graph trampoline, and avoid needing to create any special
  descriptors to hold all the functions that are being traced"

* tag 'trace-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace: Only disable ftrace_enabled to test buffer in selftest
  ftrace: Add sanity check when unregistering last ftrace_ops
  kernel: trace_syscalls: Replace rcu_assign_pointer() with RCU_INIT_POINTER()
  tracing: generate RCU warnings even when tracepoints are disabled
  ftrace: Replace tramp_hash with old_*_hash to save space
  ftrace: Annotate the ops operation on update
  ftrace: Grab any ops for a rec for enabled_functions output
  ftrace: Remove freeing of old_hash from ftrace_hash_move()
  ftrace: Set callback to ftrace_stub when no ops are registered
  ftrace: Add helper function ftrace_ops_get_func()
  ftrace: Add separate function for non recursive callbacks