 |
» |
|
|
|
|
|
|
|
|
|
Patch Name: PHKL_24256
Patch Description: s700_800 11.11 signal race condition patch/threads enh
Creation Date: 01/06/12
Post Date: 01/06/13
Hardware Platforms - OS Releases:
s700: 11.11
s800: 11.11
Products: N/A
Filesets:
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP
Automatic Reboot?: Yes
Status: General Superseded
Critical:
Yes
PHKL_24256: OTHER
Hung, Unkillable Process
Category Tags:
defect_repair general_release critical manual_dependencies
Path Name: /hp-ux_patches/s700_800/11.X/PHKL_24256
Symptoms:
PHKL_24256:
( SR:8606159451 CR:JAGad28779 ) Duplicate
( SR:8606103740 CR:JAGab70789 )
A multi-threaded process being executed over NFS can become
hung and unkillable while performing either a fork, core,
setrlimit, SIGSTOP, or debugger operations. This can happen
with mutiple threads in different processes competing for
the same resource when one thread is stopped.
PHKL_23280:
( SR:8606162688 CR:JAGad32004 )
A multithreaded process may not always perform the desired
signal handler action if the system V signal(2) interface
is used or if the SA_RESETHAND flag is set with the other
signalling interfaces. This could occur when the process
must handle more than one instance of the same signal in
parallel. Similar problems with signal handling could
occur if the user calls sigaction() while the signal is
being processed. The most likely results of handling the
action incorrectly would be for the process to be
terminated or for a user specified action to be performed
more than once before the signal action is reset to
SIG_DFL.
Defect Description:
PHKL_24256:
( SR:8606159451 CR:JAGad28779 ) Duplicate
( SR:8606103740 CR:JAGab70789 )
A thread acquires a lock and then sleeps interruptibly. The
interruptible sleep permits the thread to be stopped. Any
other thread attempting to acquire this lock will sleep
uninterruptibly until the lock is available. This
uninterruptible thread is also unkillable. This introduces
a deadlock potential in multi-threaded processes: when a
thread holding the lock, a thread desiring the lock, and a
third thread doing one of fork, setrlimit, core, SIGSTOP, or
debugger operations, all occur at the same time in the
same process, the deadlock is reached. The only way to
resolve the deadlock is to reboot the system. A similar
situation can occur when threads in different processes
are competing for the same NFS resource and the thread that
owns that resource is stopped via a signal, a debugger,
or a ctrl-Z.
This patch is part of a set of five patches (PHKL_24253,
PHKL_24254,PHKL_24255,PHKL_24256,PHKL_24257) that enable
P_NOSTOP, a new feature that prevents a process from being
unkillable. Each patch is independently installable.
Without all five installed, P_NOSTOP will be unavailable.
In order to prevent the process executed over NFS from
becoming unkillable, NFS must use the P_NOSTOP feature.
Usage of this feature was added to PHNE_23502.
Resolution:
If a thread acquires a lock and then sleeps interruptibly,
it is not permitted to be stopped if P_NOSTOP is set. This
prevents this thread from becoming unkillable and prevents
the deadlock.
PHKL_23280:
( SR:8606162688 CR:JAGad32004 )
The possibility of the wrong signal action being executed
results from a race condition that occurs between issig()
and psig(). This race condition is caused by checking the
signal's action in issig(), using that value to determine
if the signal needs to be processed by psig(), and then
releasing the thread and scheduler locks before issig()
returns. Upon returning from issig(), psig() is called and
checks the signal's action again. This leaves a window of
time that allows for the signal's action to be changed
between when issig() determines the signal should be
handled by psig() and when psig() checks what action should
be performed. The result is that the action could be
SIG_DFL, but psig() won't know how to perform the default
action for that signal.
Resolution:
psig() was modified so that it would be able to handle SIGIO
in addition to the six signals that have a default action of
ignore.
SR:
8606103740 8606159451 8606162688
Patch Files:
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
/usr/conf/lib/libpm.a(pm_signal.o)
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
/usr/conf/lib/libpm.a(pm_signal.o)
what(1) Output:
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
/usr/conf/lib/libpm.a(pm_signal.o):
pm_signal.c $Date: 2001/05/29 11:53:47 $Revision: r1
1.11/2 PATCH_11.11 (PHKL_24256)
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
/usr/conf/lib/libpm.a(pm_signal.o):
pm_signal.c $Date: 2001/05/29 11:53:47 $Revision: r1
1.11/2 PATCH_11.11 (PHKL_24256)
cksum(1) Output:
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
2231462145 25468 /usr/conf/lib/libpm.a(pm_signal.o)
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
1790640534 57216 /usr/conf/lib/libpm.a(pm_signal.o)
Patch Conflicts: None
Patch Dependencies: None
Hardware Dependencies: None
Other Dependencies:
PHKL_24256: If NFS is installed on the system, all five
patches (PHNE_23502, PHKL_24253, PHKL_24254,PHKL_24255,
PHKL_24256, PHKL_24257) are required to resolve the process
hang/deadlock due to unkillable processes executed over NFS.
However, if NFS is not in use, none of these patches are
required.
Supersedes:
PHKL_23280
Equivalent Patches:
PHKL_23407:
s700: 11.00
s800: 11.00
Patch Package Size: 110 KBytes
Installation Instructions:
Please review all instructions and the Hewlett-Packard
SupportLine User Guide or your Hewlett-Packard support terms
and conditions for precautions, scope of license,
restrictions, and, limitation of liability and warranties,
before installing this patch.
------------------------------------------------------------
1. Back up your system before installing a patch.
2. Login as root.
3. Copy the patch to the /tmp directory.
4. Move to the /tmp directory and unshar the patch:
cd /tmp
sh PHKL_24256
5. Run swinstall to install the patch:
swinstall -x autoreboot=true -x patch_match_target=true \
-s /tmp/PHKL_24256.depot
By default swinstall will archive the original software in
/var/adm/sw/save/PHKL_24256. If you do not wish to retain a
copy of the original software, include the patch_save_files
option in the swinstall command above:
-x patch_save_files=false
WARNING: If patch_save_files is false when a patch is installed,
the patch cannot be deinstalled. Please be careful
when using this feature.
For future reference, the contents of the PHKL_24256.text file is
available in the product readme:
swlist -l product -a readme -d @ /tmp/PHKL_24256.depot
To put this patch on a magnetic tape and install from the
tape drive, use the command:
dd if=/tmp/PHKL_24256.depot of=/dev/rmt/0m bs=2k
Special Installation Instructions: None
|
Printable version
