Commit-ID: 9895313534d44e714785603a2af8db928904787e
Gitweb: http://git.kernel.org/tip/9895313534d44e714785603a2af8db928904787e
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Wed, 19 Apr 2017 07:37:45 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 8 Jun 2017 08:25:27 -0700
checkpatch: Remove checks for expedited grace periods
There was a time when the expedited grace-period primitives
(synchronize_rcu_expedited(), synchronize_rcu_bh_expedited(), and
synchronize_sched_expedited()) used rather antisocial kernel
facilities like try_stop_cpus(). However, they have since been
housebroken to use only single-CPU IPIs, and typically cause less
disturbance than a scheduling-clock interrupt. Furthermore, this
disturbance can be eliminated entirely using NO_HZ_FULL on the
one hand or the rcupdate.rcu_normal boot parameter on the other.
This commit therefore removes checkpatch's complaints about use
of the expedited RCU primitives.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
scripts/checkpatch.pl | 17 -----------------
1 file changed, 17 deletions(-)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 4b9569f..c7e4d73 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5533,23 +5533,6 @@ sub process {
}
}
-# Check for expedited grace periods that interrupt non-idle non-nohz
-# online CPUs. These expedited can therefore degrade real-time response
-# if used carelessly, and should be avoided where not absolutely
-# needed. It is always OK to use synchronize_rcu_expedited() and
-# synchronize_sched_expedited() at boot time (before real-time applications
-# start) and in error situations where real-time response is compromised in
-# any case. Note that synchronize_srcu_expedited() does -not- interrupt
-# other CPUs, so don't warn on uses of synchronize_srcu_expedited().
-# Of course, nothing comes for free, and srcu_read_lock() and
-# srcu_read_unlock() do contain full memory barriers in payment for
-# synchronize_srcu_expedited() non-interruption properties.
- if ($line =~ /\b(synchronize_rcu_expedited|synchronize_sched_expedited)\(/) {
- WARN("EXPEDITED_RCU_GRACE_PERIOD",
- "expedited RCU grace periods should be avoided where they can degrade real-time response\n" . $herecurr);
-
- }
-
# check of hardware specific defines
if ($line =~ m@^.\s*\#\s*if.*\b(__i386__|__powerpc64__|__sun__|__s390x__)\b@ && $realfile !~ m@include/asm-@) {
CHK("ARCH_DEFINES",
--
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