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authorIngo Molnar <mingo@kernel.org>2015-08-12 13:12:12 +0300
committerIngo Molnar <mingo@kernel.org>2015-08-12 13:12:12 +0300
commit9b9412dc7008f360c8e8ed10a654d3c8719f69d8 (patch)
treef70ad5404519008315d576de91eb1d4fb55116d5 /scripts/checkpatch.pl
parent58ccab91342c1cc1fe08da9b198ac5d763706c2e (diff)
parent3dbe43f6fba9f2a0e46e371733575a45704c22ab (diff)
downloadlinux-9b9412dc7008f360c8e8ed10a654d3c8719f69d8.tar.xz
Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull RCU changes from Paul E. McKenney: - The combination of tree geometry-initialization simplifications and OS-jitter-reduction changes to expedited grace periods. These two are stacked due to the large number of conflicts that would otherwise result. [ With one addition, a temporary commit to silence a lockdep false positive. Additional changes to the expedited grace-period primitives (queued for 4.4) remove the cause of this false positive, and therefore include a revert of this temporary commit. ] - Documentation updates. - Torture-test updates. - Miscellaneous fixes. Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'scripts/checkpatch.pl')
-rwxr-xr-xscripts/checkpatch.pl19
1 files changed, 19 insertions, 0 deletions
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index d5c8e9a3a73c..a51ca0e5beef 100755
--- 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",