linux-toradex.git/include/linux/rcutree.h, branch v3.2.8-rt13

rcu: Fix macro substitution for synchronize_rcu_bh() on RT

2012-02-15T16:32:55+00:00

kernel/rcutorture.c:492: error: ‘synchronize_rcu_bh’ undeclared here (not in a function)

synchronize_rcu_bh() is not just called as a normal function, but can
also be referenced as a function pointer. When CONFIG_PREEMPT_RT_FULL
is enabled, synchronize_rcu_bh() is defined as synchronize_rcu(), but
needs to be defined without the parenthesis because the compiler will
complain when synchronize_rcu_bh is referenced as a function pointer
and not a function.

Signed-off-by: John Kacur 
Cc: Paul McKenney 
Cc: stable-rt@vger.kernel.org
Link: http://lkml.kernel.org/r/1321235083-21756-1-git-send-email-jkacur@redhat.com
Signed-off-by: Thomas Gleixner

rcu: Merge RCU-bh into RCU-preempt

2012-02-15T16:32:55+00:00

The Linux kernel has long RCU-bh read-side critical sections that
intolerably increase scheduling latency under mainline's RCU-bh rules,
which include RCU-bh read-side critical sections being non-preemptible.
This patch therefore arranges for RCU-bh to be implemented in terms of
RCU-preempt for CONFIG_PREEMPT_RT_FULL=y.

This has the downside of defeating the purpose of RCU-bh, namely,
handling the case where the system is subjected to a network-based
denial-of-service attack that keeps at least one CPU doing full-time
softirq processing.  This issue will be fixed by a later commit.

The current commit will need some work to make it appropriate for
mainline use, for example, it needs to be extended to cover Tiny RCU.

[ paulmck: Added a useful changelog ]

Signed-off-by: Thomas Gleixner 
Signed-off-by: Paul E. McKenney 
Link: http://lkml.kernel.org/r/20111005185938.GA20403@linux.vnet.ibm.com
Signed-off-by: Thomas Gleixner

rcu: Abstract common code for RCU grace-period-wait primitives

2011-09-29T04:36:42+00:00

Pull the code that waits for an RCU grace period into a single function,
which is then called by synchronize_rcu() and friends in the case of
TREE_RCU and TREE_PREEMPT_RCU, and from rcu_barrier() and friends in
the case of TINY_RCU and TINY_PREEMPT_RCU.

Signed-off-by: Paul E. McKenney

rcu: provide rcu_virt_note_context_switch() function.

2011-05-06T06:16:59+00:00

Provide rcu_virt_note_context_switch() for vitalization use to note
quiescent state during guest entry.

Signed-off-by: Gleb Natapov 
Signed-off-by: Paul E. McKenney

rcu: make rcutorture version numbers available through debugfs

2011-05-06T06:16:56+00:00

It is not possible to accurately correlate rcutorture output with that
of debugfs.  This patch therefore adds a debugfs file that prints out
the rcutorture version number, permitting easy correlation.

Signed-off-by: Paul E. McKenney 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

rcu,cleanup: move synchronize_sched_expedited() out of sched.c

2010-11-30T06:01:58+00:00

The first version of synchronize_sched_expedited() used the migration
code in the scheduler, and was therefore implemented in kernel/sched.c.
However, the more recent version of this code no longer uses the
migration code, so this commit moves it to the main RCU source files.

Signed-off-by: Lai Jiangshan 
Signed-off-by: Paul E. McKenney

rcu: move TINY_RCU from softirq to kthread

2010-11-17T23:45:09+00:00

If RCU priority boosting is to be meaningful, callback invocation must
be boosted in addition to preempted RCU readers.  Otherwise, in presence
of CPU real-time threads, the grace period ends, but the callbacks don't
get invoked.  If the callbacks don't get invoked, the associated memory
doesn't get freed, so the system is still subject to OOM.

But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit
moves the callback invocations to a kthread, which can be boosted easily.

Signed-off-by: Paul E. McKenney 
Signed-off-by: Paul E. McKenney

rcu: combine duplicate code, courtesy of CONFIG_PREEMPT_RCU

2010-08-20T16:00:16+00:00

The CONFIG_PREEMPT_RCU kernel configuration parameter was recently
re-introduced, but as an indication of the type of RCU (preemptible
vs. non-preemptible) instead of as selecting a given implementation.
This commit uses CONFIG_PREEMPT_RCU to combine duplicate code
from include/linux/rcutiny.h and include/linux/rcutree.h into
include/linux/rcupdate.h.  This commit also combines a few other pieces
of duplicate code that have accumulated.

Signed-off-by: Paul E. McKenney

rcu: repair code-duplication FIXMEs

2010-08-20T16:00:13+00:00

Combine the duplicate definitions of ULONG_CMP_GE(), ULONG_CMP_LT(),
and rcu_preempt_depth() into include/linux/rcupdate.h.

Signed-off-by: Paul E. McKenney

rcu: permit suppressing current grace period's CPU stall warnings

2010-08-20T16:00:12+00:00

When using a kernel debugger, a long sojourn in the debugger can get
you lots of RCU CPU stall warnings once you resume.  This might not be
helpful, especially if you are using the system console.  This patch
therefore allows RCU CPU stall warnings to be suppressed, but only for
the duration of the current set of grace periods.

This differs from Jason's original patch in that it adds support for
tiny RCU and preemptible RCU, and uses a slightly different method for
suppressing the RCU CPU stall warning messages.

Signed-off-by: Jason Wessel 
Signed-off-by: Paul E. McKenney 
Tested-by: Jason Wessel