RHBA-2011:1192 - Bug Fix Advisory

Topic

Updated kernel-rt packages that fix several bugs and add various enhancements
are now available for Red Hat Enterprise MRG 2.0.

Description

The kernel-rt packages contain the Linux kernel, the core of any Linux operating
system.

This update provides a build of the kernel-rt package for MRG 2.0, which is
layered on Red Hat Enterprise Linux 6.

Bug Fixes:

• The Realtime Kernel implemented a set of too strict checks related to

"si_code" causing the user space glibc's AIO (Asynchronous I/O Overview)
implementation to receive permission errors (EPERM) in legitimate requests. The
"si_code" check has been slightly relaxed to remove these errors. (BZ#711205)

• System interrupts were disabled before the ftrace utility performed a code

modification of mcounts into nops causing large latencies (up to 1ms) when
inserting modules during an ftrace session. ftrace was modified to only disable
the interrupts on start up around the code in question. Interrupts now remain
enabled when modules are being loaded, reducing the latencies during an ftrace
session. (BZ#715418)

• A missing directory in the kernel-rt-devel packages, which contains header

files, prevented third-party modules from being built using only the
kernel-rt-devel package. Adding these missing files now allows third-party
modules to be successfully built. (BZ#718940)

• Enabling the CONFIG_SYSFS_DEPRECATED configuration option, which forces the

use of the old style SYSFS layout, on the Red Hat Enterprise MRG 2.0 Realtime
vanilla Kernel (kernel-rt-vanilla) confused certain userspace tools, such as
udev, that rely on the newer SYSFS layout. CONFIG_SYSFS_DEPRECATED has been
disabled in the configuration file for the Realtime vanilla Kernel
(kernel-rt-vanilla), which allows udev to execute without warnings while using
the newer SYSFS layout. (BZ#710124)

• If the NEED_RESCHED flag is set in the MRG Realtime Kernel, the wrong task was

being tested by the scheduler. An extra scheduling pass was then required, which
added overhead to the scheduler and could introduce scheduling delays. The
correct behavior is implemented by checking the task that is running on the
runqueue when another task is about to be woken. (BZ#717081)

• The TSC clocksource may have been erroneously disabled due to false positives

in the clocksource watchdog tests because this code could be interrupted. To
avoid these false positives, both reads, watchdog and TSC, were moved into a
short interrupt disabled region. TSC is no longer erroneously disabled due to
false positives. (BZ#717083)

Enhancements:

• The Brocade FC adapter driver present in Red Hat Enterprise MRG 2.0 has been

upgraded to the same version level as the driver in Red Hat Enterprise Linux
version 6 and is now enabled in the Realtime Kernel. (BZ#712422)

• The following network drivers in Red Hat Enterprise MRG 2.0 have been upgraded

to the same version level as the drivers in Red Hat Enterprise Linux version 6:
Broadcom bnx2 and bnx2x drivers, Brocade bna driver, Tigon3 / tg3 driver,
Chelsio cxgb3 driver, Cisco enic driver, Emulex be2net driver, HP NC-Series
NetXen driver, Intel e100, e1000, e1000e, igb, and ixgbe drivers, and Myricom
myri10g driver. (BZ#707259)

Users of the Realtime capabilities of Red Hat Enterprise MRG 2.0, which is
layered on Red Hat Enterprise Linux 6, are advised to upgrade to these updated
packages, which resolve these issues and add these enhancements. Note that the
system must be rebooted for this update to take effect.

Solution

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

This update is available via 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

To install kernel packages manually, use "rpm -ivh [package]". Do not use "rpm

• Uvh" as that will remove the running kernel binaries from your system. You may

use "rpm -e" to remove old kernels after determining that the new kernel
functions properly on your system.

Affected Products

• MRG Realtime 2 x86_64

Fixes

• BZ - 707259 - [RFE] rebase network drivers for MRG 2.0
• BZ - 711205 - [REGRESSION] In rt31.64.el5rt regression in signal.c
• BZ - 712422 - There is no driver for Brocade FC adapter in kernel-rt-2.6.33.9-rt31.64.el5rt
• BZ - 715418 - ftrace causing large latency when inserting module

CVEs

(none)

References

(none)