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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-04-19 07:37:45 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-06-08 08:25:27 -0700
commit9895313534d44e714785603a2af8db928904787e (patch)
tree6ac8b34efeaa447b61a19aa0962c57ae87c8772b /scripts/checkpatch.pl
parentdcfc315b7b7a5e7668dd9cb2474708b51ab1cdb1 (diff)
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@linux.vnet.ibm.com>
Diffstat (limited to 'scripts/checkpatch.pl')
-rwxr-xr-xscripts/checkpatch.pl17
1 files changed, 0 insertions, 17 deletions
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 4b9569fa931b..c7e4d73fe1ce 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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