[SYSTEMTAP/PATCH 0/4] RT aware systemtap patch set

[Santosh Shukla <sshukla at mvista dot com>]

Hi,

I wanted to run systemtap on -rt kernel version 3.14.12-rt9 and noticed bunch of preemptible
bug_on.This is initial effort to make systemtap rt-aware. Tested on 3.14.12-rt
kernel.  Patchset based on stap upstream link [1], build on commit-id [2].
Patchset can work on master branch with little tweak in patch set.

I have also tested this patch set in 3.10.40-rt38 kernel noticed few preemptible
bug_on but those were coming from kernel and no improvement observed in
systemtap side.

Change summary -
- Replaced read lock with rcu_read_lock such that read_lock_irqsave lock substituion is
  rcu_read_lock + local_irq_save and for read_unlock_irqsave lock substitution is 
  local_irq_restore followed bu rcu_read_unlock.

- Replaced write_lock_irqsave/restore with raw_spinlock_irqsave/restore for -rt kernel.
  And for non-rt kernel those raw_ lock should get replaced by normal spin_lock.

- Replaced hlist api to rcu type api.

Test script used for testing :
/usr/local/stap/bin/stap -v testsuite/systemtap.examples/network/netdev.stp
/usr/local/stap/bin/stap -v testsuite/systemtap.examples/network/tcpdumplike.stp

Few other test example script used :
cat ../test-indent.stp
probe kernel.function("*@net/socket.c").call
{
	          printf ("%s -> %s\n", thread_indent(1), probefunc())
}
probe kernel.function("*@net/socket.c").return
{
	          printf ("%s <- %s\n", thread_indent(-1), probefunc())
}


Like know feedback, comment on patch set. also Does it make sense to maintain
systemtap -rt version in upstream.. do we care?

[1] git://sourceware.org/git/systemtap.git
[2] git checkout 8f0fcd995f7f650a2ee0a94539f90c99e6d19e1d

Santosh Shukla (4):
  rt : replace __stp_tf_task_work_list_lock to raw_
  rt : replace read write lock with rcu
  rt : stp_utrace.c : replace utrace->lock with raw_lock
  rt : replace utrace_struct lock to raw lock

 runtime/linux/addr-map.c        |   16 ++++---
 runtime/linux/runtime.h         |    2 +-
 runtime/linux/task_finder2.c    |   14 +++---
 runtime/linux/task_finder_map.c |   38 ++++++++-------
 runtime/stp_utrace.c            |  100 +++++++++++++++++++--------------------
 runtime/task_finder_vma.c       |   43 +++++++++--------
 6 files changed, 112 insertions(+), 101 deletions(-)

-- 
1.7.9.5