systemtap bug fix update

Updated systemtap packages that fix various bugs are now available for Red Hat
Enterprise Linux 5.

SystemTap provides infrastructure to simplify the gathering of information about
the running Linux system. This assists diagnosis of a performance or a
functional problem. Developers can write scripts to collect data without the
need to go through the tedious and disruptive instrument, recompile, install,
and reboot sequence that may be otherwise required to collect data.

The systemtap package has been upgraded to upstream version 1.6, which provides
a number of bug fixes and enhancements over the previous version. (BZ#683481)

This update fixes the following bugs:

* When running the "with server" portion of the SystemTap buildok test suite,
the server needs an authorized certificate for signing the code the compiler
server built. In some cases, a client running the test suite never obtained the
authorized certificate. Consequently, additional failures were reported by the
test suite compared to the self-hosted buildok test runs. This bug has been
fixed and now, results for the "with server" portion of test suite and the
self-hosted test suite match. (BZ#718678)

* The systemtap data structure to track address accesses requires a locking
mechanism to prevent data corruption. Previously, spinlocks were used but they
caused kernel panics if excessive contention for reading the data structure
occurred. With this update, the locking mechanism has been changed to rwlock,
which allows concurrent reading of the data structure, thus fixing this bug.
(BZ#709190)

* For some error conditions (such as "out of memory"), the debugfs directory
associated with a systemtap script remained in the system even after the script
exited. Consequently, other scripts run afterwards were unable to create their
own debugfs directory until the system had been rebooted. With this update, the
runtime transport code has been updated to remove debugfs directories every time
a systemtap script exits. (BZ#711976)

* Previously, tracepoint names for softirq probe points (used in older kernels)
and for the irq.stp tapset (used in newer kernels) did not match. Consequently,
the softirq.* probe points were not found on kernels in Red Hat Enterprise Linux
5. Now, the irq.stp tapset has been updated to allow systemtap to find older
softirq probe points in older kernels. (BZ#706185)

* In some cases, the operands in the newest version of user-space markers could
not be parsed, causing some tests to fail. With this update, SystemTap parsing
of marker arguments has been fixed to handle the operands for the newest version
of user-space markers and the tests now pass as expected. (BZ#757118)

* The memory-write_shared_copy.stp test uses the memory.stp tapset's
vm.write_shared_copy probe. In earlier versions of systemtap, this probe was a
dummy, letting the test case falsely pass. In later versions, it became a real
probe, but due to incomplete debug information generated by the gcc compiler, it
cannot be fully resolved on a Red Hat Enterprise Linux 5 kernel. Consequently,
the test case fails. This appeared as a regression, because the earlier pass of
the test was in fact false. With this update, this test case has been designated
as a "KFAIL" (known failure) and is no longer considered a regression.
(BZ#757723)

Users of systemtap are advised to upgrade to these updated packages, which fix
these bugs.

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259

683481 - Rebase to systemtap 1.6 for rhel5.8
706185 - softirq.* probes do not work on el5 kernels
757118 - semok/thirtysix.stp PASS -> FAIL
757723 - buildok/memory-write_shared_copy.stp fails to build