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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>
zero-colors
Paul E. McKenney 2017-04-19 07:37:45 -07:00
parent dcfc315b7b
commit 9895313534
1 changed files with 0 additions and 17 deletions
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17
scripts/checkpatch.pl
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@ -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",