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authorLinus Torvalds <torvalds@linux-foundation.org>2015-08-31 18:12:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-08-31 18:12:07 -0700
commit7073bc66126e3ab742cce9416ad6b4be8b03c4f7 (patch)
tree18f7d5f3de8a6070481d347e792d9d358813b6b7 /scripts
parentd4c90396ed7ef9b4e4d221e008e54be8bea8307f (diff)
parentf612a7b1a7f1b5139f228724ce340aac24720591 (diff)
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar: "The main RCU changes in this cycle are: - 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. - privatize smp_mb__after_unlock_lock(). This commit moves the definition of smp_mb__after_unlock_lock() to kernel/rcu/tree.h, in recognition of the fact that RCU is the only thing using this, that nothing else is likely to use it, and that it is likely to go away completely. - documentation updates. - torture-test updates. - misc fixes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) rcu,locking: Privatize smp_mb__after_unlock_lock() rcu: Silence lockdep false positive for expedited grace periods rcu: Don't disable CPU hotplug during OOM notifiers scripts: Make checkpatch.pl warn on expedited RCU grace periods rcu: Update MAINTAINERS entry rcu: Clarify CONFIG_RCU_EQS_DEBUG help text rcu: Fix backwards RCU_LOCKDEP_WARN() in synchronize_rcu_tasks() rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN() rcu: Make rcu_is_watching() really notrace cpu: Wait for RCU grace periods concurrently rcu: Create a synchronize_rcu_mult() rcu: Fix obsolete priority-boosting comment rcu: Use WRITE_ONCE in RCU_INIT_POINTER rcu: Hide RCU_NOCB_CPU behind RCU_EXPERT rcu: Add RCU-sched flavors of get-state and cond-sync rcu: Add fastpath bypassing funnel locking rcu: Rename RCU_GP_DONE_FQS to RCU_GP_DOING_FQS rcu: Pull out wait_event*() condition into helper function documentation: Describe new expedited stall warnings rcu: Add stall warnings to synchronize_sched_expedited() ...
Diffstat (limited to 'scripts')
-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",

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