rcu_cpu_has_callbacks() is declared int. The current declaration was introduced
in commit c0f4dfd4f9 (rcu: Make RCU_FAST_NO_HZ take advantage of numbered
callbacks). But it is actually returning bool and as the function description
states " * Return true if the specified CPU has any callback....", this probably
should be a bool as all (3) call-sites currently treat it as bool.
Type-checking coccinelle spatches are being used to locate type mismatches
between function signatures and return values in this case this produced:
./kernel/rcu/tree.c:3538 WARNING: return of wrong type
int != bool,
Patch was compile tested with x86_64_defconfig (implies CONFIG_TREE_RCU=y)
Patch is against 4.1-rc3 (localversion-next is -next-20150511) and fixes
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
rcu_bh_data, rcu_sched_data and rcu_preempt_data are never used outside
kernel/rcu/tree.c and thus can be made static.
Doing so fixes a section mismatch warning reported by clang when
building LLVMLinux with -Wsection, because these variables were declared
in .data..percpu and defined in .data..percpu..shared_aligned since
commit 11bbb235c2 ("rcu: Use DEFINE_PER_CPU_SHARED_ALIGNED for
rcu_data").
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Currently, synchronize_sched_expedited() will call synchronize_sched()
if there is danger of counter wrap. But if configuration says to
always do expedited grace periods, synchronize_sched() will just
call synchronize_sched_expedited() right back again. In theory,
the old expedited operations will complete, the counters will
get back in synch, and the recursion will end. But we could
easily run out of stack long before that time. This commit
therefore makes synchronize_sched_expedited() invoke the underlying
wait_rcu_gp(call_rcu_sched) instead of synchronize_sched(), the same as
all the other calls out from synchronize_sched_expedited().
This bug was introduced by commit 1924bcb025 (Avoid counter wrap in
synchronize_sched_expedited()).
Reported-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit adds grace number and command-flags information to the
"kthread starved" message that is sometimes printed out as part of
RCU CPU stall warnings. This message is caused by the corresponding
RCU grace-period kthread not having run for at least two seconds, and
this added information can be helpful when debugging.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The first item list_for_each_entry_continue(alist) iterates over is
alist->next, rather than alist itself. Consequently,
rcu_print_detail_task_stall_rnp() skips the task referenced by gp_tasks.
Use gp_tasks->prev as the argument to list_for_each_entry_continue()
instead.
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Use the normal return values for bool functions
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The rcu_gp_kthread_wake() refuses to do a wakeup unless at least
one of the ->gp_flags bits are set, which normally will not be the
case when the last quiescent state is reported. This results in
up to a 3-jiffy delay given default Kconfig settings. This commit
therefore has rcu_report_qs_rsp() set RCU_GP_FLAG_FQS before invoking
rcu_gp_kthread_wake() in order to force a more immediate wakeup at
grace-period end, thus reducing grace-period latencies.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit converts several CONFIG_RCU_NOCB_CPU_ALL #ifdefs to
instead use IS_ENABLED(). This change should help avoid hiding
code from compiler diagnostics.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit creates an immutable rcu_data_p pointer that references
rcu_preempt_data for TREE_PREEMPT_RCU builds and that references
rcu_sched_data for TREE_RCU builds. This rcu_data_p pointer will enable
more code to move from #ifdef to IS_ENABLED().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit adds a "const" tag to the declarations of rcu_state_p,
which should allow the compiler to generate better code and also to
catch erroneous assignments to this variable.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit removes a few RCU_BOOST #ifdefs, replacing them with
IS_ENABLED()-protected return statements. This relies on the
optimizer to remove any resulting dead code. There are several other
RCU_BOOST #ifdefs, however these rely on some per-CPU variables that
are available only under RCU_BOOST. These might be converted later,
if the simplification proves to outweigh the increase in memory footprint.
One hoped-for advantage is more easily locating compiler errors in
obscure combinations of Kconfig parameters.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: <linux-rt-users@vger.kernel.org>
It would be good to move more code from #ifdef to IS_ENABLED(), but
that does not work if the body of the IS_ENABLED() "if" statement
references a variable (such as rcu_preempt_state) that does not
exist if the IS_ENABLED() Kconfig variable is not set. This commit
therefore substitutes *rcu_state_p for all uses of rcu_preempt_state
in kernel/rcu/tree_preempt.h, which should enable elimination of
a few #ifdefs.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit moves from the old ACCESS_ONCE() API to the new READ_ONCE()
and WRITE_ONCE() APIs.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Updated to include kernel/torture.c as suggested by Jason Low. ]
In a misguided attempt to avoid an #ifdef, the use of the
gp_init_delay module parameter was conditioned on the corresponding
RCU_TORTURE_TEST_SLOW_INIT Kconfig variable, using IS_ENABLED() at
the point of use in the code. This meant that the compiler always saw
the delay, which meant that RCU_TORTURE_TEST_SLOW_INIT_DELAY had to be
unconditionally defined. This in turn caused "make oldconfig" to ask
pointless questions about the value of RCU_TORTURE_TEST_SLOW_INIT_DELAY
in cases where it was not even used.
This commit avoids these pointless questions by defining gp_init_delay
under #ifdef. In one branch, gp_init_delay is initialized to
RCU_TORTURE_TEST_SLOW_INIT_DELAY and is also a module parameter (thus
allowing boot-time modification), and in the other branch gp_init_delay
is a const variable initialized by default to zero.
This approach also simplifies the code at the delay point by eliminating
the IS_DEFINED(). Because gp_init_delay is constant zero in the no-delay
case intended for production use, the "gp_init_delay > 0" check causes
the delay to become dead code, as desired in this case. In addition,
this commit replaces magic constant "10" with the preprocessor variable
PER_RCU_NODE_PERIOD, which controls the number of grace periods that
are allowed to elapse at full speed before a delay is inserted.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
Paul E. McKenney <paulmck@linux.vnet.ibm.com>
As noted in earlier commit logs, CPU hotplug operations running
concurrently with grace-period initialization can result in a given
leaf rcu_node structure having all CPUs offline and no blocked readers,
but with this rcu_node structure nevertheless blocking the current
grace period. Therefore, the quiescent-state forcing code now checks
for this situation and repairs it.
Unfortunately, this checking can result in false positives, for example,
when the last task has just removed itself from this leaf rcu_node
structure, but has not yet started clearing the ->qsmask bits further
up the structure. This means that the grace-period kthread (which
forces quiescent states) and some other task might be attempting to
concurrently clear these ->qsmask bits. This is usually not a problem:
One of these tasks will be the first to acquire the upper-level rcu_node
structure's lock and with therefore clear the bit, and the other task,
seeing the bit already cleared, will stop trying to clear bits.
Sadly, this means that the following unusual sequence of events -can-
result in a problem:
1. The grace-period kthread wins, and clears the ->qsmask bits.
2. This is the last thing blocking the current grace period, so
that the grace-period kthread clears ->qsmask bits all the way
to the root and finds that the root ->qsmask field is now zero.
3. Another grace period is required, so that the grace period kthread
initializes it, including setting all the needed qsmask bits.
4. The leaf rcu_node structure (the one that started this whole
mess) is blocking this new grace period, either because it
has at least one online CPU or because there is at least one
task that had blocked within an RCU read-side critical section
while running on one of this leaf rcu_node structure's CPUs.
(And yes, that CPU might well have gone offline before the
grace period in step (3) above started, which can mean that
there is a task on the leaf rcu_node structure's ->blkd_tasks
list, but ->qsmask equal to zero.)
5. The other kthread didn't get around to trying to clear the upper
level ->qsmask bits until all the above had happened. This means
that it now sees bits set in the upper-level ->qsmask field, so it
proceeds to clear them. Too bad that it is doing so on behalf of
a quiescent state that does not apply to the current grace period!
This sequence of events can result in the new grace period being too
short. It can also result in the new grace period ending before the
leaf rcu_node structure's ->qsmask bits have been cleared, which will
result in splats during initialization of the next grace period. In
addition, it can result in tasks blocking the new grace period still
being queued at the start of the next grace period, which will result
in other splats. Sasha's testing turned up another of these splats,
as did rcutorture testing. (And yes, rcutorture is being adjusted to
make these splats show up more quickly. Which probably is having the
undesirable side effect of making other problems show up less quickly.
Can't have everything!)
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> # 4.0.x
Tested-by: Sasha Levin <sasha.levin@oracle.com>
As noted earlier, the following sequence of events can occur when
running PREEMPT_RCU and HOTPLUG_CPU on a system with a multi-level
rcu_node combining tree:
1. A group of tasks block on CPUs corresponding to a given leaf
rcu_node structure while within RCU read-side critical sections.
2. All CPUs corrsponding to that rcu_node structure go offline.
3. The next grace period starts, but because there are still tasks
blocked, the upper-level bits corresponding to this leaf rcu_node
structure remain set.
4. All the tasks exit their RCU read-side critical sections and
remove themselves from the leaf rcu_node structure's list,
leaving it empty.
5. But because there now is code to check for this condition at
force-quiescent-state time, the upper bits are cleared and the
grace period completes.
However, there is another complication that can occur following step 4 above:
4a. The grace period starts, and the leaf rcu_node structure's
gp_tasks pointer is set to NULL because there are no tasks
blocked on this structure.
4b. One of the CPUs corresponding to the leaf rcu_node structure
comes back online.
4b. An endless stream of tasks are preempted within RCU read-side
critical sections on this CPU, such that the ->blkd_tasks
list is always non-empty.
The grace period will never end.
This commit therefore makes the force-quiescent-state processing check only
for absence of tasks blocking the current grace period rather than absence
of tasks altogether. This will cause a quiescent state to be reported if
the current leaf rcu_node structure is not blocking the current grace period
and its parent thinks that it is, regardless of how RCU managed to get
itself into this state.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> # 4.0.x
Tested-by: Sasha Levin <sasha.levin@oracle.com>
At grace-period initialization time, RCU checks that all quiescent
states were really reported for the previous grace period. Now that
grace-period cleanup has been split out of grace-period initialization,
this commit also performs those checks at grace-period cleanup time.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit informs RCU of an outgoing CPU just before that CPU invokes
arch_cpu_idle_dead() during its last pass through the idle loop (via a
new CPU_DYING_IDLE notifier value). This change means that RCU need not
deal with outgoing CPUs passing through the scheduler after informing
RCU that they are no longer online. Note that removing the CPU from
the rcu_node ->qsmaskinit bit masks is done at CPU_DYING_IDLE time,
and orphaning callbacks is still done at CPU_DEAD time, the reason being
that at CPU_DEAD time we have another CPU that can adopt them.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Because that RCU grace-period initialization need no longer exclude
CPU-hotplug operations, this commit eliminates the ->onoff_mutex and
its uses.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Races between CPU hotplug and grace periods can be difficult to resolve,
so the ->onoff_mutex is used to exclude the two events. Unfortunately,
this means that it is impossible for an outgoing CPU to perform the
last bits of its offlining from its last pass through the idle loop,
because sleeplocks cannot be acquired in that context.
This commit avoids these problems by buffering online and offline events
in a new ->qsmaskinitnext field in the leaf rcu_node structures. When a
grace period starts, the events accumulated in this mask are applied to
the ->qsmaskinit field, and, if needed, up the rcu_node tree. The special
case of all CPUs corresponding to a given leaf rcu_node structure being
offline while there are still elements in that structure's ->blkd_tasks
list is handled using a new ->wait_blkd_tasks field. In this case,
propagating the offline bits up the tree is deferred until the beginning
of the grace period after all of the tasks have exited their RCU read-side
critical sections and removed themselves from the list, at which point
the ->wait_blkd_tasks flag is cleared. If one of that leaf rcu_node
structure's CPUs comes back online before the list empties, then the
->wait_blkd_tasks flag is simply cleared.
This of course means that RCU's notion of which CPUs are offline can be
out of date. This is OK because RCU need only wait on CPUs that were
online at the time that the grace period started. In addition, RCU's
force-quiescent-state actions will handle the case where a CPU goes
offline after the grace period starts.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The rcu_report_unblock_qs_rnp() function is invoked when the
last task blocking the current grace period exits its outermost
RCU read-side critical section. Previously, this was called only
from rcu_read_unlock_special(), and was therefore defined only when
CONFIG_RCU_PREEMPT=y. However, this function will be invoked even when
CONFIG_RCU_PREEMPT=n once CPU-hotplug operations are processed only at
the beginnings of RCU grace periods. The reason for this change is that
the last task on a given leaf rcu_node structure's ->blkd_tasks list
might well exit its RCU read-side critical section between the time that
recent CPU-hotplug operations were applied and when the new grace period
was initialized. This situation could result in RCU waiting forever on
that leaf rcu_node structure, because if all that structure's CPUs were
already offline, there would be no quiescent-state events to drive that
structure's part of the grace period.
This commit therefore moves rcu_report_unblock_qs_rnp() to common code
that is built unconditionally so that the quiescent-state-forcing code
can clean up after this situation, avoiding the grace-period stall.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Currently, the rcu_node tree ->expmask bitmasks are initially set to
reflect the online CPUs. This is pointless, because only the CPUs
preempted within RCU read-side critical sections by the preceding
synchronize_sched_expedited() need to be tracked. This commit therefore
instead sets up these bitmasks based on the state of the ->blkd_tasks
lists.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Offline CPUs cannot safely invoke trace events, but such CPUs do execute
within rcu_cpu_notify(). Therefore, this commit removes the trace events
from rcu_cpu_notify(). These trace events are for utilization, against
which rcu_cpu_notify() execution time should be negligible.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Grace-period initialization normally proceeds quite quickly, so
that it is very difficult to reproduce races against grace-period
initialization. This commit therefore allows grace-period
initialization to be artificially slowed down, increasing
race-reproduction probability. A pair of new Kconfig parameters are
provided, CONFIG_RCU_TORTURE_TEST_SLOW_INIT to enable the slowdowns, and
CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY to specify the number of jiffies
of slowdown to apply. A boot-time parameter named rcutree.gp_init_delay
allows boot-time delay to be specified. By default, no delay will be
applied even if CONFIG_RCU_TORTURE_TEST_SLOW_INIT is set.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
If all CPUs have passed through quiescent states, then stalls might be
due to starvation of the grace-period kthread or to failure to propagate
the quiescent states up the rcu_node combining tree. The current stall
warning messages do not differentiate, so this commit adds a printout
of the root rcu_node structure's ->qsmask field.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Currently, both rcu_cleanup_dead_cpu() and rcu_send_cbs_to_orphanage()
initialize the outgoing CPU's callback list. However, only
rcu_cleanup_dead_cpu() invokes rcu_send_cbs_to_orphanage(), and
it does so unconditionally, which means that only one of these
initializations is required. This commit therefore consolidates the
callback-list initialization with the rest of the callback handling in
rcu_send_cbs_to_orphanage().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Because invoke_cpu_core() checks whether the current CPU is online,
there is no need for __call_rcu_core() to redundantly check it.
There should not be any performance degradation because the called
function is visible to the compiler. This commit therefore removes
the redundant check.
Signed-off-by: Yao Dongdong <yaodongdong@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The very similar functions rcu_force_quiescent_state(),
rcu_bh_force_quiescent_state(), and rcu_sched_force_quiescent_state()
are supposed to be together, but have drifted apart. This commit
restores rcu_sched_force_quiescent_state() to its rightful place.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
If an RCU read-side critical section occurs within an interrupt handler
or a softirq handler, it cannot have been preempted. Therefore, there is
a check in rcu_read_unlock_special() checking for this error. However,
when this check triggers, it lacks diagnostic information. This commit
therefore moves rcu_read_unlock()'s lockdep annotation to follow the
call to __rcu_read_unlock() and changes rcu_read_unlock_special()'s
WARN_ON_ONCE() to an lockdep_rcu_suspicious() in order to locate where
the offending RCU read-side critical section began. In addition, the
value of the ->rcu_read_unlock_special field is printed.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit uses IS_ENABLED() to remove the #ifdef from the
rcu_init_levelspread() functions. No effect on executable code.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Because callbacks can now be posted quite early in boot, move the
early boot callback tests to precede RCU initialization.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
When a CPU is first determined to be a no-CBs CPUs, this commit causes
any early boot callbacks to be moved to the no-CBs callback list,
allowing them to be invoked.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
If the RCU grace-period kthread invoking rcu_sysidle_check_cpu()
happens to be running on the tick_do_timer_cpu initially,
then rcu_bind_gp_kthread() won't bind it. This kthread might
then migrate before invoking rcu_gp_fqs(), which will trigger the
WARN_ON_ONCE() in rcu_sysidle_check_cpu(). This commit therefore makes
rcu_bind_gp_kthread() do the binding even if the kthread is currently
on the same CPU. Because this incurs added overhead, this commit also
causes each RCU grace-period kthread to invoke rcu_bind_gp_kthread()
once at boot rather than at the beginning of each grace period.
And as long as rcu_bind_gp_kthread() is being modified, this commit
eliminates its #ifdef.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The standard code path accommodates a condition when no
RCU callbacks are ready to invoke. Since size of the code
is a priority for tiny RCU, remove the fast path.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
When the ->curtail and ->donetail pointers differ, ->rcucblist
always points to the beginning of the current list and thus
cannot be NULL. Therefore, the check ->rcucblist != NULL is
redundant and this commit removes it.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
On second and subsequent passes through quiescent-state forcing, the
isidle variable was initialized to false, which would prevent full sysidle
state from being reached if a grace period needed more than one round
of quiescent-state forcing (which most should not). However, the check
for offline CPUs in the quiescent-state forcing main loop had the wrong
sense, which could prevent CPUs from ever entering full sysidle state.
This commit fixes both of these bugs. Given that sysidle is not yet
wired up, this has no effect in old kernels, but might have proven
frustrating had anyone attempted to wire it up.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The "if" statement at the beginning of rcu_torture_writer() should
use the same set of variables. In theory, this does not matter because
the corresponding variables (gp_sync and gp_sync1) have the same value
at this point in the code, but in practice such puzzles should be
removed. This commit therefore makes the use of variables consistent.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit adds a CONFIG_RCU_EXPEDITE_BOOT Kconfig parameter
that emulates a very early boot rcu_expedite_gp(). A late-boot
call to rcu_end_inkernel_boot() will provide the corresponding
rcu_unexpedite_gp(). The late-boot call to rcu_end_inkernel_boot()
should be made just before init is spawned.
According to Arjan:
> To show the boot time, I'm using the timestamp of the "Write protecting"
> line, that's pretty much the last thing we print prior to ring 3 execution.
>
> A kernel with default RCU behavior (inside KVM, only virtual devices)
> looks like this:
>
> [ 0.038724] Write protecting the kernel read-only data: 10240k
>
> a kernel with expedited RCU (using the command line option, so that I
> don't have to recompile between measurements and thus am completely
> oranges-to-oranges)
>
> [ 0.031768] Write protecting the kernel read-only data: 10240k
>
> which, in percentage, is an 18% improvement.
Reported-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Arjan van de Ven <arjan@linux.intel.com>
This commit updates open-coded tests of the rcu_expedited variable
to instead use rcu_gp_is_expedited().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Currently, expediting of normal synchronous grace-period primitives
(synchronize_rcu() and friends) is controlled by the rcu_expedited()
boot/sysfs parameter. This works well, but does not handle nesting.
This commit therefore provides rcu_expedite_gp() to enable expediting
and rcu_unexpedite_gp() to cancel a prior rcu_expedite_gp(), both of
which support nesting.
Reported-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
When a CPU comes online, it initializes its callback list. This
is a bad thing if this is the first time that the CPU has come
online and if that CPU has early boot callbacks. This commit therefore
avoid initializing the callback list if there are callbacks present,
in which case the initial call_rcu() did the initialization for us.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Some diagnostics under CONFIG_PROVE_RCU in rcu_nocb_cpu_needs_barrier()
assume that there can be no early-boot callbacks. This commit therefore
qualifies the diagnostic with rcu_scheduler_fully_active to permit
early boot callbacks to avoid this splat.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
