10 Nov, 2009
3 commits
-
Impose a clear locking design on the rcu_process_gp_end()
function's use of the ->completed counter. This is done by
creating a ->completed field in the rcu_node structure, which
can safely be accessed under the protection of that structure's
lock. Performance and scalability are maintained by using a
form of double-checked locking, so that rcu_process_gp_end()
only acquires the leaf rcu_node structure's ->lock if a grace
period has recently ended.This fix reduces rcutorture failure rate by at least two orders
of magnitude under heavy stress with force_quiescent_state()
being invoked artificially often. Without this fix,
unsynchronized access to the ->completed field can cause
rcu_process_gp_end() to advance callbacks whose grace period has
not yet expired. (Bad idea!)Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: # .32.x
LKML-Reference:
Signed-off-by: Ingo Molnar -
Impose a clear locking design on non-NO_HZ handling of the
->completed counter. This increases the distance between the
RCU and the CPU-hotplug mechanisms.Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: # .32.x
LKML-Reference:
Signed-off-by: Ingo Molnar -
Merge reason: Pick up RCU fixlet to base further commits on.
Signed-off-by: Ingo Molnar
02 Nov, 2009
3 commits
-
Currently, rcu_irq_exit() is invoked only for CONFIG_NO_HZ,
while rcu_irq_enter() is invoked unconditionally. This patch
moves rcu_irq_exit() out from under CONFIG_NO_HZ so that the
calls are balanced.This patch has no effect on the behavior of the kernel because
both rcu_irq_enter() and rcu_irq_exit() are empty for
!CONFIG_NO_HZ, but the code is easier to understand if the calls
are obviously balanced in all cases.Signed-off-by: Lai Jiangshan
Signed-off-by: Paul E. McKenney
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
Very long RCU read-side critical sections (50 milliseconds or
so) can cause a race between force_quiescent_state() and
rcu_start_gp() as follows on kernel builds with multi-level
rcu_node hierarchies:1. CPU 0 calls force_quiescent_state(), sees that there is a
grace period in progress, and acquires ->fsqlock.2. CPU 1 detects the end of the grace period, and so
cpu_quiet_msk_finish() sets rsp->completed to rsp->gpnum.
This operation is carried out under the root rnp->lock,
but CPU 0 has not yet acquired that lock. Note that
rsp->signaled is still RCU_SAVE_DYNTICK from the last
grace period.3. CPU 1 calls rcu_start_gp(), but no one wants a new grace
period, so it drops the root rnp->lock and returns.4. CPU 0 acquires the root rnp->lock and picks up rsp->completed
and rsp->signaled, then drops rnp->lock. It then enters the
RCU_SAVE_DYNTICK leg of the switch statement.5. CPU 2 invokes call_rcu(), and now needs a new grace period.
It calls rcu_start_gp(), which acquires the root rnp->lock, sets
rsp->signaled to RCU_GP_INIT (too bad that CPU 0 is already in
the RCU_SAVE_DYNTICK leg of the switch statement!) and starts
initializing the rcu_node hierarchy. If there are multiple
levels to the hierarchy, it will drop the root rnp->lock and
initialize the lower levels of the hierarchy.6. CPU 0 notes that rsp->completed has not changed, which permits
both CPU 2 and CPU 0 to try updating it concurrently. If CPU 0's
update prevails, later calls to force_quiescent_state() can
count old quiescent states against the new grace period, which
can in turn result in premature ending of grace periods.Not good.
This patch adds an RCU_GP_IDLE state for rsp->signaled that is
set initially at boot time and any time a grace period ends.
This prevents CPU 0 from getting into the workings of
force_quiescent_state() in step 4. Additional locking and
checks prevent the concurrent update of rsp->signaled in step 6.Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
Ingo triggered the following warning:
WARNING: at lib/debugobjects.c:255 debug_print_object+0x42/0x50()
Hardware name: System Product Name
ODEBUG: init active object type: timer_list
Modules linked in:
Pid: 2619, comm: dmesg Tainted: G W 2.6.32-rc5-tip+ #5298
Call Trace:
[] warn_slowpath_common+0x6a/0x81
[] ? debug_print_object+0x42/0x50
[] warn_slowpath_fmt+0x29/0x2c
[] debug_print_object+0x42/0x50
[] __debug_object_init+0x279/0x2d7
[] debug_object_init+0x13/0x18
[] init_timer_key+0x17/0x6f
[] free_uid+0x50/0x6c
[] put_cred_rcu+0x61/0x72
[] rcu_do_batch+0x70/0x121debugobjects warns about an enqueued timer being initialized. If
CONFIG_USER_SCHED=y the user management code uses delayed work to
remove the user from the hash table and tear down the sysfs objects.free_uid is called from RCU and initializes/schedules delayed work if
the usage count of the user_struct is 0. The init/schedule happens
outside of the uidhash_lock protected region which allows a concurrent
caller of find_user() to reference the about to be destroyed
user_struct w/o preventing the work from being scheduled. If the next
free_uid call happens before the work timer expired then the active
timer is initialized and the work scheduled again.The race was introduced in commit 5cb350ba (sched: group scheduling,
sysfs tunables) and made more prominent by commit 3959214f (sched:
delayed cleanup of user_struct)Move the init/schedule_delayed_work inside of the uidhash_lock
protected region to prevent the race.Signed-off-by: Thomas Gleixner
Acked-by: Dhaval Giani
Cc: Paul E. McKenney
Cc: Kay Sievers
Cc: stable@kernel.org
29 Oct, 2009
1 commit
-
The requeue_pi path doesn't use unqueue_me() (and the racy lock_ptr ==
NULL test) nor does it use the wake_list of futex_wake() which where
the reason for commit 41890f2 (futex: Handle spurious wake up)See debugging discussing on LKML Message-ID:
The changes in this fix to the wait_requeue_pi path were considered to
be a likely unecessary, but harmless safety net. But it turns out that
due to the fact that for unknown $@#!*( reasons EWOULDBLOCK is defined
as EAGAIN we built an endless loop in the code path which returns
correctly EWOULDBLOCK.Spurious wakeups in wait_requeue_pi code path are unlikely so we do
the easy solution and return EWOULDBLOCK^WEAGAIN to user space and let
it deal with the spurious wakeup.Cc: Darren Hart
Cc: Peter Zijlstra
Cc: Eric Dumazet
Cc: John Stultz
Cc: Dinakar Guniguntala
LKML-Reference:
Cc: stable@kernel.org
Signed-off-by: Thomas Gleixner
27 Oct, 2009
2 commits
-
Some compilers are happy with "#elif CONFIG_RCU_TINY", while
others strongly prefer "#elif defined(CONFIG_RCU_TINY)". Change
to the latter to make more compilers happy.Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
Use lockdep_set_class() to simplify the code and to avoid any
additional overhead in the !LOCKDEP case. Also move the
definition of rcu_root_class into kernel/rcutree.c, as suggested
by Lai Jiangshan.Signed-off-by: Peter Zijlstra
Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar
26 Oct, 2009
6 commits
-
No change in functionality - just straighten out a few small
stylistic details.Cc: Paul E. McKenney
Cc: David Howells
Cc: Josh Triplett
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: avi@redhat.com
Cc: mtosatti@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
Make rcutorture list the available torture_type values when it
doesn't like the one specified.Signed-off-by: Paul E. McKenney
Acked-by: Josh Triplett
Reviewed-by: Lai Jiangshan
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: avi@redhat.com
Cc: mtosatti@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
Signed-off-by: Paul E. McKenney
Acked-by: Josh Triplett
Reviewed-by: Lai Jiangshan
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: avi@redhat.com
Cc: mtosatti@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
Adds the "srcu_expedited" torture type, and also renames
sched_ops_sync to sched_sync_ops for consistency while we are in
this file.Signed-off-by: Paul E. McKenney
Acked-by: Josh Triplett
Reviewed-by: Lai Jiangshan
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: avi@redhat.com
Cc: mtosatti@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
This patch creates a synchronize_srcu_expedited() that uses
synchronize_sched_expedited() where synchronize_srcu()
uses synchronize_sched(). The synchronize_srcu() and
synchronize_srcu_expedited() functions become one-liners that
pass synchronize_sched() or synchronize_sched_expedited(),
repectively, to a new __synchronize_srcu() function.While in the file, move the EXPORT_SYMBOL_GPL()s to immediately
follow the corresponding functions.Requested-by: Avi Kivity
Tested-by: Marcelo Tosatti
Signed-off-by: Paul E. McKenney
Acked-by: Josh Triplett
Reviewed-by: Lai Jiangshan
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: avi@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
This patch is a version of RCU designed for !SMP provided for a
small-footprint RCU implementation. In particular, the
implementation of synchronize_rcu() is extremely lightweight and
high performance. It passes rcutorture testing in each of the
four relevant configurations (combinations of NO_HZ and PREEMPT)
on x86. This saves about 1K bytes compared to old Classic RCU
(which is no longer in mainline), and more than three kilobytes
compared to Hierarchical RCU (updated to 2.6.30):CONFIG_TREE_RCU:
text data bss dec filename
183 4 0 187 kernel/rcupdate.o
2783 520 36 3339 kernel/rcutree.o
3526 Total (vs 4565 for v7)CONFIG_TREE_PREEMPT_RCU:
text data bss dec filename
263 4 0 267 kernel/rcupdate.o
4594 776 52 5422 kernel/rcutree.o
5689 Total (6155 for v7)CONFIG_TINY_RCU:
text data bss dec filename
96 4 0 100 kernel/rcupdate.o
734 24 0 758 kernel/rcutiny.o
858 Total (vs 848 for v7)The above is for x86. Your mileage may vary on other platforms.
Further compression is possible, but is being procrastinated.Changes from v7 (http://lkml.org/lkml/2009/10/9/388)
o Apply Lai Jiangshan's review comments (aside from
might_sleep() in synchronize_sched(), which is covered by SMP builds).o Fix up expedited primitives.
Changes from v6 (http://lkml.org/lkml/2009/9/23/293).
o Forward ported to put it into the 2.6.33 stream.
o Added lockdep support.
o Make lightweight rcu_barrier.
Changes from v5 (http://lkml.org/lkml/2009/6/23/12).
o Ported to latest pre-2.6.32 merge window kernel.
- Renamed rcu_qsctr_inc() to rcu_sched_qs().
- Renamed rcu_bh_qsctr_inc() to rcu_bh_qs().
- Provided trivial rcu_cpu_notify().
- Provided trivial exit_rcu().
- Provided trivial rcu_needs_cpu().
- Fixed up the rcu_*_enter/exit() functions in linux/hardirq.h.o Removed the dependence on EMBEDDED, with a view to making
TINY_RCU default for !SMP at some time in the future.o Added (trivial) support for expedited grace periods.
Changes from v4 (http://lkml.org/lkml/2009/5/2/91) include:
o Squeeze the size down a bit further by removing the
->completed field from struct rcu_ctrlblk.o This permits synchronize_rcu() to become the empty function.
Previous concerns about rcutorture were unfounded, as
rcutorture correctly handles a constant value from
rcu_batches_completed() and rcu_batches_completed_bh().Changes from v3 (http://lkml.org/lkml/2009/3/29/221) include:
o Changed rcu_batches_completed(), rcu_batches_completed_bh()
rcu_enter_nohz(), rcu_exit_nohz(), rcu_nmi_enter(), and
rcu_nmi_exit(), to be static inlines, as suggested by David
Howells. Doing this saves about 100 bytes from rcutiny.o.
(The numbers between v3 and this v4 of the patch are not directly
comparable, since they are against different versions of Linux.)Changes from v2 (http://lkml.org/lkml/2009/2/3/333) include:
o Fix whitespace issues.
o Change short-circuit "||" operator to instead be "+" in order
to fix performance bug noted by "kraai" on LWN.(http://lwn.net/Articles/324348/)
Changes from v1 (http://lkml.org/lkml/2009/1/13/440) include:
o This version depends on EMBEDDED as well as !SMP, as suggested
by Ingo.o Updated rcu_needs_cpu() to unconditionally return zero,
permitting the CPU to enter dynticks-idle mode at any time.
This works because callbacks can be invoked upon entry to
dynticks-idle mode.o Paul is now OK with this being included, based on a poll at
the Kernel Miniconf at linux.conf.au, where about ten people said
that they cared about saving 900 bytes on single-CPU systems.o Applies to both mainline and tip/core/rcu.
Signed-off-by: Paul E. McKenney
Acked-by: David Howells
Acked-by: Josh Triplett
Reviewed-by: Lai Jiangshan
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: avi@redhat.com
Cc: mtosatti@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar
16 Oct, 2009
2 commits
-
When requeuing tasks from one futex to another, the reference held
by the requeued task to the original futex location needs to be
dropped eventually.Dropping the reference may ultimately lead to a call to
"iput_final" and subsequently call into filesystem- specific code -
which may be non-atomic.It is therefore safer to defer this drop operation until after the
futex_hash_bucket spinlock has been dropped.Originally-From: Helge Bahmann
Signed-off-by: Darren Hart
Cc:
Cc: Peter Zijlstra
Cc: Eric Dumazet
Cc: Dinakar Guniguntala
Cc: John Stultz
Cc: Sven-Thorsten Dietrich
Cc: John Kacur
LKML-Reference:
Signed-off-by: Ingo Molnar -
If the following sequence of events occurs, then
TREE_PREEMPT_RCU will hang waiting for a grace period to
complete, eventually OOMing the system:o A TREE_PREEMPT_RCU build of the kernel is booted on a system
with more than 64 physical CPUs present (32 on a 32-bit system).
Alternatively, a TREE_PREEMPT_RCU build of the kernel is booted
with RCU_FANOUT set to a sufficiently small value that the
physical CPUs populate two or more leaf rcu_node structures.o A task is preempted in an RCU read-side critical section
while running on a CPU corresponding to a given leaf rcu_node
structure.o All CPUs corresponding to this same leaf rcu_node structure
record quiescent states for the current grace period.o All of these same CPUs go offline (hence the need for enough
physical CPUs to populate more than one leaf rcu_node structure).
This causes the preempted task to be moved to the root rcu_node
structure.At this point, there is nothing left to cause the quiescent
state to be propagated up the rcu_node tree, so the current
grace period never completes.The simplest fix, especially after considering the deadlock
possibilities, is to detect this situation when the last CPU is
offlined, and to set that CPU's ->qsmask bit in its leaf
rcu_node structure. This will cause the next invocation of
force_quiescent_state() to end the grace period.Without this fix, this hang can be triggered in an hour or so on
some machines with rcutorture and random CPU onlining/offlining.
With this fix, these same machines pass a full 10 hours of this
sort of abuse.Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar
15 Oct, 2009
6 commits
-
Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: npiggin@suse.de
Cc: jens.axboe@oracle.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
o Remove the CONFIG_PREEMPT_RCU documentation since this
config option has now been removed.o Change the now-incorrect references to "rcu" labels to
instead be "rcu_sched".o Add notes stating that CONFIG_TREE_PREEMPT_RCU kernels will
have additional "rcu_preempt" output.o Note the new "oqlen" field in the rcuhier output (for
RCU callbacks orphaned by an offlined CPU).Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: npiggin@suse.de
Cc: jens.axboe@oracle.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: npiggin@suse.de
Cc: jens.axboe@oracle.com
Cc: Josh Triplett
LKML-Reference:
Signed-off-by: Ingo Molnar
kernel/rcutree_trace.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-) -
For the short term, map synchronize_rcu_expedited() to
synchronize_rcu() for TREE_PREEMPT_RCU and to
synchronize_sched_expedited() for TREE_RCU.Longer term, there needs to be a real expedited grace period for
TREE_PREEMPT_RCU, but candidate patches to date are considerably
more complex and intrusive.Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: npiggin@suse.de
Cc: jens.axboe@oracle.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
As the number of callbacks on a given CPU rises, invoke
force_quiescent_state() only every blimit number of callbacks
(defaults to 10,000), and even then only if no other CPU has
invoked force_quiescent_state() in the meantime.This should fix the performance regression reported by Nick.
Reported-by: Nick Piggin
Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: jens.axboe@oracle.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
If userspace tries to perform a requeue_pi on a non-requeue_pi waiter,
it will find the futex_q->requeue_pi_key to be NULL and OOPS.Check for NULL in match_futex() instead of doing explicit NULL pointer
checks on all call sites. While match_futex(NULL, NULL) returning
false is a little odd, it's still correct as we expect valid key
references.Signed-off-by: Darren Hart
Cc: Peter Zijlstra
Cc: Ingo Molnar
CC: Eric Dumazet
CC: Dinakar Guniguntala
CC: John Stultz
Cc: stable@kernel.org
LKML-Reference:
Signed-off-by: Thomas Gleixner
14 Oct, 2009
1 commit
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The futex code does not handle spurious wake up in futex_wait and
futex_wait_requeue_pi.The code assumes that any wake up which was not caused by futex_wake /
requeue or by a timeout was caused by a signal wake up and returns one
of the syscall restart error codes.In case of a spurious wake up the signal delivery code which deals
with the restart error codes is not invoked and we return that error
code to user space. That causes applications which actually check the
return codes to fail. Blaise reported that on preempt-rt a python test
program run into a exception trap. -rt exposed that due to a built in
spurious wake up accelerator :)Solve this by checking signal_pending(current) in the wake up path and
handle the spurious wake up case w/o returning to user space.Reported-by: Blaise Gassend
Debugged-by: Darren Hart
Signed-off-by: Thomas Gleixner
Cc: Peter Zijlstra
Cc: stable@kernel.org
LKML-Reference:
13 Oct, 2009
1 commit
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…file into core/urgent
10 Oct, 2009
2 commits
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A race shouldn't happen since all workqueues or handlers are canceled
or flushed before the event buffer is freed. A warning is triggered
now if the buffer is freed too early.Also, this patch adds some comments about event buffer protection,
reworks some code and adds code to clear buffer_pos during alloc and
free of the event buffer.Cc: David Rientjes
Cc: Stephane Eranian
Signed-off-by: Robert Richter -
Looking at the 2.6.31-rc9 code, it appears there is a race condition
in the event_buffer cleanup code path (shutdown). This could lead to
kernel panic as some CPUs may be operating on the event buffer AFTER
it has been freed. The attached patch solves the problem and makes
sure CPUs check if the buffer is not NULL before they access it as
some may have been spinning on the mutex while the buffer was being
freed.The race may happen if the buffer is freed during pending reads. But
it is not clear why there are races in add_event_entry() since all
workqueues or handlers are canceled or flushed before the event buffer
is freed.Signed-off-by: David Rientjes
Signed-off-by: Stephane Eranian
Signed-off-by: Robert Richter
09 Oct, 2009
13 commits
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Some tracepoint magic (TRACE_EVENT(lock_acquired)) relies on
the fact that lock hold times are positive and uses div64 on
that. That triggered a build warning on MIPS, and probably
causes bad output in certain circumstances as well.Make it truly positive.
Reported-by: Andrew Morton
Signed-off-by: Peter Zijlstra
LKML-Reference:
Signed-off-by: Ingo Molnar -
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev:
pata_atp867x: add Power Management support
pata_atp867x: PIO support fixes
pata_atp867x: clarifications in timings calculations and cable detection
pata_atp867x: fix it to not claim MWDMA support
libata: fix incorrect link online check during probe
ahci: filter FPDMA non-zero offset enable for Aspire 3810T
libata: make gtf_filter per-dev
libata: implement more acpi filtering options
libata: cosmetic updates
ahci: display all AHCI 1.3 HBA capability flags (v2)
pata_ali: trivial fix of a very frequent spelling mistake
ahci: disable 64bit DMA by default on SB600s -
…/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
futex: fix requeue_pi key imbalance
futex: Fix typo in FUTEX_WAIT/WAKE_BITSET_PRIVATE definitions
rcu: Place root rcu_node structure in separate lockdep class
rcu: Make hot-unplugged CPU relinquish its own RCU callbacks
rcu: Move rcu_barrier() to rcutree
futex: Move exit_pi_state() call to release_mm()
futex: Nullify robust lists after cleanup
futex: Fix locking imbalance
panic: Fix panic message visibility by calling bust_spinlocks(0) before dying
rcu: Replace the rcu_barrier enum with pointer to call_rcu*() function
rcu: Clean up code based on review feedback from Josh Triplett, part 4
rcu: Clean up code based on review feedback from Josh Triplett, part 3
rcu: Fix rcu_lock_map build failure on CONFIG_PROVE_LOCKING=y
rcu: Clean up code to address Ingo's checkpatch feedback
rcu: Clean up code based on review feedback from Josh Triplett, part 2
rcu: Clean up code based on review feedback from Josh Triplett -
…l/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: Set correct normal_prio and prio values in sched_fork() -
…git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, pci: Correct spelling in a comment
x86: Simplify bound checks in the MTRR code
x86: EDAC: carve out AMD MCE decoding logic
initcalls: Add early_initcall() for modules
x86: EDAC: MCE: Fix MCE decoding callback logic -
…nel/git/tip/linux-2.6-tip
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
tracing: user local buffer variable for trace branch tracer
tracing: fix warning on kernel/trace/trace_branch.c andtrace_hw_branches.c
ftrace: check for failure for all conversions
tracing: correct module boundaries for ftrace_release
tracing: fix transposed numbers of lock_depth and preempt_count
trace: Fix missing assignment in trace_ctxwake_*
tracing: Use free_percpu instead of kfree
tracing: Check total refcount before releasing bufs in profile_enable failure -
…/linux/kernel/git/tip/linux-2.6-tip
* 'sparc-perf-events-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
mm, perf_event: Make vmalloc_user() align base kernel virtual address to SHMLBA
perf_event: Provide vmalloc() based mmap() backing -
…el/git/tip/linux-2.6-tip
* 'perf-fixes-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
perf_events: Make ABI definitions available to userspace
perf tools: elf_sym__is_function() should accept "zero" sized functions
tracing/syscalls: Use long for syscall ret format and field definitions
perf trace: Update eval_flag() flags array to match interrupt.h
perf trace: Remove unused code in builtin-trace.c
perf: Propagate term signal to child -
…el/git/tip/linux-2.6-tip
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, timers: Check for pending timers after (device) interrupts
NOHZ: update idle state also when NOHZ is inactive -
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
ALSA: ice1724: increase SPDIF and independent stereo buffer sizes
ALSA: opl3: circular locking in the snd_opl3_note_on() and snd_opl3_note_off()
ALSA: ICE1712/24 - Change the Multi Track Peak control (level meters) from MIXER to PCM type
ALSA: hda - Fix yet another auto-mic bug in ALC268
ASoC: WM8350 capture PGA mutes are inverted
ASoC: Remove absent SYNC and TDM DAI format options from i.MX SSI
sound: via82xx: move DXS volume controls to PCM interface
ALSA: hda - Don't pick up invalid HP pins in alc_subsystem_id()
ALSA: hda - Add a workaround for ASUS A7K
ALSA: hda - Fix invalid initializations for ALC861 auto mode
ASoC: wm8940: Fix check on error code form snd_soc_codec_set_cache_io
ASoC: Fix SND_SOC_DAPM_LINE handling -
* 'drm-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6: (24 commits)
drm/radeon/kms: fix vline register for second head.
drm/r600: avoid assigning vb twice in blit code
drm/radeon: use list_for_each_entry instead of list_for_each
drm/radeon/kms: Fix AGP support for R600/RV770 family (v2)
drm/radeon/kms: Fallback to non AGP when acceleration fails to initialize (v2)
drm/radeon/kms: Fix RS600/RV515/R520/RS690 IRQ
drm/radeon: Fix setting of bits
drm/ttm: fix refcounting in ttm global code.
drm/fb: add more correct 8/16/24/32 bpp fb support.
drm/fb: add setcmap and fix 8-bit support.
drm/radeon/kms: respect single crtc cards, only create one crtc. (v2)
drm: Delete the DRM_DEBUG_KMS in drm_mode_cursor_ioctl
drm/radeon/kms: add support for "Surround View"
drm/radeon/kms: Fix irq handling on AVIVO hw
drm/radeon/kms: R600/RV770 remove dead code and print message for wrong BIOS
drm/radeon/kms: Fix R600/RV770 disable acceleration path
drm/radeon/kms: Fix R600/RV770 startup path & reset
drm/radeon/kms: Fix R600 write back buffer
drm/radeon/kms: Remove old init path as no hw use it anymore
drm/radeon/kms: Convert RS600 to new init path
... -
…/git/tmlind/linux-omap-2.6
* 'omap-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap-2.6:
omapfb: Blizzard: constify register address tables
omapfb: Blizzard: fix pointer to be const
omapfb: Condition mutex acquisition
omap: iovmm: Add missing mutex_unlock
omap: iovmm: Fix incorrect spelling
omap: SRAM: flush the right address after memcpy in omap_sram_push
omap: Lock DPLL5 at boot
omap: Fix incorrect 730 vs 850 detection
OMAP3: PM: introduce a new powerdomain walk helper
OMAP3: PM: Enable GPIO module-level wakeups
OMAP3: PM: USBHOST: clear wakeup events on both hosts
OMAP3: PM: PRCM interrupt: only handle selected PRCM interrupts
OMAP3: PM: PRCM interrupt: check MPUGRPSEL register
OMAP3: PM: Prevent hang in prcm_interrupt_handler -
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/bp/bp:
amd64_edac: beef up DRAM error injection
amd64_edac: fix DRAM base and limit extraction
amd64_edac: fix chip select handling
amd64_edac: simple fix to allow reporting of CECC errors
amd64_edac: fix K8 intlv_sel check
amd64_edac: fix interleave enable tests
amd64_edac: fix DRAM base and limit address extraction
amd64_edac: fix driver instance lookup table allocation
