From 9895313534d44e714785603a2af8db928904787e Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 19 Apr 2017 07:37:45 -0700 Subject: [PATCH] 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 --- scripts/checkpatch.pl | 17 ----------------- 1 file changed, 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", -- 2.20.1