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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-04-19 16:37:45 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-06-08 17:25:27 +0200 |
| commit | 9895313534d44e714785603a2af8db928904787e (patch) | |
| tree | 6ac8b34efeaa447b61a19aa0962c57ae87c8772b /scripts | |
| parent | rcu: Make sync_rcu_preempt_exp_done() return bool (diff) | |
| download | linux-9895313534d44e714785603a2af8db928904787e.tar.xz linux-9895313534d44e714785603a2af8db928904787e.zip | |
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')
| -rwxr-xr-x | scripts/checkpatch.pl | 17 |
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", |