Currently, we get the following output from sputrace:

[5.097935954] 1606: spufs_ps_nopfn__enter (thread = 1605, spu = -1)
[5.097958164] 1606: spufs_ps_nopfn__insert (thread = 1605, spu = 15)
[5.097973529] 1607: spufs_ps_nopfn__enter (thread = 1605, spu = -1)
[5.097989174] 1607: spufs_ps_nopfn__insert (thread = 1605, spu = 14)

Which leads me to believe that 160[67] is the current thread ID, and
1605 is the context backing the psmap.

However, the 'current' and 'owner' tids are reversed - the 'current'
tid is on the right. This change puts the current thread ID in the
left-hand column instead, and renames the right to 'ctxthread'.
Signed-off-by: NJeremy Kerr <jk@ozlabs.org>

RCU style multiple probes support for the Linux Kernel Markers.  Common case
(one probe) is still fast and does not require dynamic allocation or a
supplementary pointer dereference on the fast path.

- Move preempt disable from the marker site to the callback.

Since we now have an internal callback, move the preempt disable/enable to the
callback instead of the marker site.

Since the callback change is done asynchronously (passing from a handler that
supports arguments to a handler that does not setup the arguments is no
arguments are passed), we can safely update it even if it is outside the
preempt disable section.

- Move probe arm to probe connection. Now, a connected probe is automatically
  armed.

Remove MARK_MAX_FORMAT_LEN, unused.

This patch modifies the Linux Kernel Markers API : it removes the probe
"arm/disarm" and changes the probe function prototype : it now expects a
va_list * instead of a "...".

If we want to have more than one probe connected to a marker at a given
time (LTTng, or blktrace, ssytemtap) then we need this patch. Without it,
connecting a second probe handler to a marker will fail.

It allow us, for instance, to do interesting combinations :

Do standard tracing with LTTng and, eventually, to compute statistics
with SystemTAP, or to have a special trigger on an event that would call
a systemtap script which would stop flight recorder tracing.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Mike Mason <mmlnx@us.ibm.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: David Smith <dsmith@redhat.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This adds markers two important points in the spufs code and a new
module (sputrace.ko) that allows reading these out through a proc file.

Long-term I'd rather see something like lttng extended to use the spufs
instrumentation, but for now I think this is a good enough quick
solution.  We'll probably want to add various addition event in addition
to that ones I have already.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJeremy Kerr <jk@ozlabs.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>