scripts/Lindent: handle missing indent gracefully

[cascardo/linux.git] / scripts / checkpatch.pl

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index d5c8e9a..a51ca0e 100755 (executable)
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5011,6 +5011,7 @@ sub process {
                                     "memory barrier without comment\n" . $herecurr);
                        }
                }
+
 # check for waitqueue_active without a comment.
                if ($line =~ /\bwaitqueue_active\s*\(/) {
                        if (!ctx_has_comment($first_line, $linenr)) {
@@ -5018,6 +5019,24 @@ sub process {
                                     "waitqueue_active without comment\n" . $herecurr);
                        }
                }
+
+# Check for expedited grace periods that interrupt non-idle non-nohz
+# online CPUs.  These expedited can therefore degrade real-time response
+# if used carelessly, and should be avoided where not absolutely
+# needed.  It is always OK to use synchronize_rcu_expedited() and
+# synchronize_sched_expedited() at boot time (before real-time applications
+# start) and in error situations where real-time response is compromised in
+# any case.  Note that synchronize_srcu_expedited() does -not- interrupt
+# other CPUs, so don't warn on uses of synchronize_srcu_expedited().
+# Of course, nothing comes for free, and srcu_read_lock() and
+# srcu_read_unlock() do contain full memory barriers in payment for
+# synchronize_srcu_expedited() non-interruption properties.
+               if ($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",