Merge tag 'locking-core-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "These are the locking updates for v5.10:

   - Add deadlock detection for recursive read-locks.

     The rationale is outlined in commit 224ec489d3cd ("lockdep/
     Documention: Recursive read lock detection reasoning")

     The main deadlock pattern we want to detect is:

           TASK A:                 TASK B:

           read_lock(X);
                                   write_lock(X);
           read_lock_2(X);

   - Add "latch sequence counters" (seqcount_latch_t):

     A sequence counter variant where the counter even/odd value is used
     to switch between two copies of protected data. This allows the
     read path, typically NMIs, to safely interrupt the write side
     critical section.

     We utilize this new variant for sched-clock, and to make x86 TSC
     handling safer.

   - Other seqlock cleanups, fixes and enhancements

   - KCSAN updates

   - LKMM updates

   - Misc updates, cleanups and fixes"

* tag 'locking-core-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits)
  lockdep: Revert "lockdep: Use raw_cpu_*() for per-cpu variables"
  lockdep: Fix lockdep recursion
  lockdep: Fix usage_traceoverflow
  locking/atomics: Check atomic-arch-fallback.h too
  locking/seqlock: Tweak DEFINE_SEQLOCK() kernel doc
  lockdep: Optimize the memory usage of circular queue
  seqlock: Unbreak lockdep
  seqlock: PREEMPT_RT: Do not starve seqlock_t writers
  seqlock: seqcount_LOCKNAME_t: Introduce PREEMPT_RT support
  seqlock: seqcount_t: Implement all read APIs as statement expressions
  seqlock: Use unique prefix for seqcount_t property accessors
  seqlock: seqcount_LOCKNAME_t: Standardize naming convention
  seqlock: seqcount latch APIs: Only allow seqcount_latch_t
  rbtree_latch: Use seqcount_latch_t
  x86/tsc: Use seqcount_latch_t
  timekeeping: Use seqcount_latch_t
  time/sched_clock: Use seqcount_latch_t
  seqlock: Introduce seqcount_latch_t
  mm/swap: Do not abuse the seqcount_t latching API
  time/sched_clock: Use raw_read_seqcount_latch() during suspend
  ...

2 files changed, 430 insertions, 20 deletions

diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index 3d282d51849b..f271ff5fbb5a 100644
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -40,6 +40,11 @@ menuconfig KCSAN
 
 if KCSAN
 
+# Compiler capabilities that should not fail the test if they are unavailable.
+config CC_HAS_TSAN_COMPOUND_READ_BEFORE_WRITE
+	def_bool (CC_IS_CLANG && $(cc-option,-fsanitize=thread -mllvm -tsan-compound-read-before-write=1)) || \
+		 (CC_IS_GCC && $(cc-option,-fsanitize=thread --param tsan-compound-read-before-write=1))
+
 config KCSAN_VERBOSE
 	bool "Show verbose reports with more information about system state"
 	depends on PROVE_LOCKING
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index 14f44f59e733..a899b3f0e2e5 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -28,6 +28,7 @@
  * Change this to 1 if you want to see the failure printouts:
  */
 static unsigned int debug_locks_verbose;
+unsigned int force_read_lock_recursive;
 
 static DEFINE_WD_CLASS(ww_lockdep);
 
@@ -399,6 +400,49 @@ static void rwsem_ABBA1(void)
  * read_lock(A)
  * spin_lock(B)
  *		spin_lock(B)
+ *		write_lock(A)
+ *
+ * This test case is aimed at poking whether the chain cache prevents us from
+ * detecting a read-lock/lock-write deadlock: if the chain cache doesn't differ
+ * read/write locks, the following case may happen
+ *
+ * 	{ read_lock(A)->lock(B) dependency exists }
+ *
+ * 	P0:
+ * 	lock(B);
+ * 	read_lock(A);
+ *
+ *	{ Not a deadlock, B -> A is added in the chain cache }
+ *
+ *	P1:
+ *	lock(B);
+ *	write_lock(A);
+ *
+ *	{ B->A found in chain cache, not reported as a deadlock }
+ *
+ */
+static void rlock_chaincache_ABBA1(void)
+{
+	RL(X1);
+	L(Y1);
+	U(Y1);
+	RU(X1);
+
+	L(Y1);
+	RL(X1);
+	RU(X1);
+	U(Y1);
+
+	L(Y1);
+	WL(X1);
+	WU(X1);
+	U(Y1); // should fail
+}
+
+/*
+ * read_lock(A)
+ * spin_lock(B)
+ *		spin_lock(B)
  *		read_lock(A)
  */
 static void rlock_ABBA2(void)
@@ -991,6 +1035,133 @@ GENERATE_PERMUTATIONS_3_EVENTS(irq_inversion_soft_wlock)
 #undef E3
 
 /*
+ * write-read / write-read / write-read deadlock even if read is recursive
+ */
+
+#define E1()				\
+					\
+	WL(X1);				\
+	RL(Y1);				\
+	RU(Y1);				\
+	WU(X1);
+
+#define E2()				\
+					\
+	WL(Y1);				\
+	RL(Z1);				\
+	RU(Z1);				\
+	WU(Y1);
+
+#define E3()				\
+					\
+	WL(Z1);				\
+	RL(X1);				\
+	RU(X1);				\
+	WU(Z1);
+
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(W1R2_W2R3_W3R1)
+
+#undef E1
+#undef E2
+#undef E3
+
+/*
+ * write-write / read-read / write-read deadlock even if read is recursive
+ */
+
+#define E1()				\
+					\
+	WL(X1);				\
+	WL(Y1);				\
+	WU(Y1);				\
+	WU(X1);
+
+#define E2()				\
+					\
+	RL(Y1);				\
+	RL(Z1);				\
+	RU(Z1);				\
+	RU(Y1);
+
+#define E3()				\
+					\
+	WL(Z1);				\
+	RL(X1);				\
+	RU(X1);				\
+	WU(Z1);
+
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(W1W2_R2R3_W3R1)
+
+#undef E1
+#undef E2
+#undef E3
+
+/*
+ * write-write / read-read / read-write is not deadlock when read is recursive
+ */
+
+#define E1()				\
+					\
+	WL(X1);				\
+	WL(Y1);				\
+	WU(Y1);				\
+	WU(X1);
+
+#define E2()				\
+					\
+	RL(Y1);				\
+	RL(Z1);				\
+	RU(Z1);				\
+	RU(Y1);
+
+#define E3()				\
+					\
+	RL(Z1);				\
+	WL(X1);				\
+	WU(X1);				\
+	RU(Z1);
+
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(W1R2_R2R3_W3W1)
+
+#undef E1
+#undef E2
+#undef E3
+
+/*
+ * write-read / read-read / write-write is not deadlock when read is recursive
+ */
+
+#define E1()				\
+					\
+	WL(X1);				\
+	RL(Y1);				\
+	RU(Y1);				\
+	WU(X1);
+
+#define E2()				\
+					\
+	RL(Y1);				\
+	RL(Z1);				\
+	RU(Z1);				\
+	RU(Y1);
+
+#define E3()				\
+					\
+	WL(Z1);				\
+	WL(X1);				\
+	WU(X1);				\
+	WU(Z1);
+
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(W1W2_R2R3_R3W1)
+
+#undef E1
+#undef E2
+#undef E3
+/*
  * read-lock / write-lock recursion that is actually safe.
  */
 
@@ -1009,20 +1180,28 @@ GENERATE_PERMUTATIONS_3_EVENTS(irq_inversion_soft_wlock)
 #define E3()				\
 					\
 	IRQ_ENTER();			\
-	RL(A);				\
+	LOCK(A);			\
 	L(B);				\
 	U(B);				\
-	RU(A);				\
+	UNLOCK(A);			\
 	IRQ_EXIT();
 
 /*
- * Generate 12 testcases:
+ * Generate 24 testcases:
  */
 #include "locking-selftest-hardirq.h"
-GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion_hard)
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion_hard_rlock)
+
+#include "locking-selftest-wlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion_hard_wlock)
 
 #include "locking-selftest-softirq.h"
-GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion_soft)
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion_soft_rlock)
+
+#include "locking-selftest-wlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion_soft_wlock)
 
 #undef E1
 #undef E2
@@ -1036,8 +1215,8 @@ GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion_soft)
 					\
 	IRQ_DISABLE();			\
 	L(B);				\
-	WL(A);				\
-	WU(A);				\
+	LOCK(A);			\
+	UNLOCK(A);			\
 	U(B);				\
 	IRQ_ENABLE();
 
@@ -1054,13 +1233,75 @@ GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion_soft)
 	IRQ_EXIT();
 
 /*
- * Generate 12 testcases:
+ * Generate 24 testcases:
  */
 #include "locking-selftest-hardirq.h"
-// GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion2_hard)
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion2_hard_rlock)
+
+#include "locking-selftest-wlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion2_hard_wlock)
 
 #include "locking-selftest-softirq.h"
-// GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion2_soft)
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion2_soft_rlock)
+
+#include "locking-selftest-wlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion2_soft_wlock)
+
+#undef E1
+#undef E2
+#undef E3
+/*
+ * read-lock / write-lock recursion that is unsafe.
+ *
+ * A is a ENABLED_*_READ lock
+ * B is a USED_IN_*_READ lock
+ *
+ * read_lock(A);
+ *			write_lock(B);
+ * <interrupt>
+ * read_lock(B);
+ * 			write_lock(A); // if this one is read_lock(), no deadlock
+ */
+
+#define E1()				\
+					\
+	IRQ_DISABLE();			\
+	WL(B);				\
+	LOCK(A);			\
+	UNLOCK(A);			\
+	WU(B);				\
+	IRQ_ENABLE();
+
+#define E2()				\
+					\
+	RL(A);				\
+	RU(A);				\
+
+#define E3()				\
+					\
+	IRQ_ENTER();			\
+	RL(B);				\
+	RU(B);				\
+	IRQ_EXIT();
+
+/*
+ * Generate 24 testcases:
+ */
+#include "locking-selftest-hardirq.h"
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion3_hard_rlock)
+
+#include "locking-selftest-wlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion3_hard_wlock)
+
+#include "locking-selftest-softirq.h"
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion3_soft_rlock)
+
+#include "locking-selftest-wlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion3_soft_wlock)
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 # define I_SPINLOCK(x)	lockdep_reset_lock(&lock_##x.dep_map)
@@ -1199,6 +1440,19 @@ static inline void print_testname(const char *testname)
 	dotest(name##_##nr, FAILURE, LOCKTYPE_RWLOCK);		\
 	pr_cont("\n");
 
+#define DO_TESTCASE_1RR(desc, name, nr)				\
+	print_testname(desc"/"#nr);				\
+	pr_cont("             |");				\
+	dotest(name##_##nr, SUCCESS, LOCKTYPE_RWLOCK);		\
+	pr_cont("\n");
+
+#define DO_TESTCASE_1RRB(desc, name, nr)			\
+	print_testname(desc"/"#nr);				\
+	pr_cont("             |");				\
+	dotest(name##_##nr, FAILURE, LOCKTYPE_RWLOCK);		\
+	pr_cont("\n");
+
+
 #define DO_TESTCASE_3(desc, name, nr)				\
 	print_testname(desc"/"#nr);				\
 	dotest(name##_spin_##nr, FAILURE, LOCKTYPE_SPIN);	\
@@ -1213,6 +1467,25 @@ static inline void print_testname(const char *testname)
 	dotest(name##_rlock_##nr, SUCCESS, LOCKTYPE_RWLOCK);	\
 	pr_cont("\n");
 
+#define DO_TESTCASE_2RW(desc, name, nr)				\
+	print_testname(desc"/"#nr);				\
+	pr_cont("      |");					\
+	dotest(name##_wlock_##nr, FAILURE, LOCKTYPE_RWLOCK);	\
+	dotest(name##_rlock_##nr, SUCCESS, LOCKTYPE_RWLOCK);	\
+	pr_cont("\n");
+
+#define DO_TESTCASE_2x2RW(desc, name, nr)			\
+	DO_TESTCASE_2RW("hard-"desc, name##_hard, nr)		\
+	DO_TESTCASE_2RW("soft-"desc, name##_soft, nr)		\
+
+#define DO_TESTCASE_6x2x2RW(desc, name)				\
+	DO_TESTCASE_2x2RW(desc, name, 123);			\
+	DO_TESTCASE_2x2RW(desc, name, 132);			\
+	DO_TESTCASE_2x2RW(desc, name, 213);			\
+	DO_TESTCASE_2x2RW(desc, name, 231);			\
+	DO_TESTCASE_2x2RW(desc, name, 312);			\
+	DO_TESTCASE_2x2RW(desc, name, 321);
+
 #define DO_TESTCASE_6(desc, name)				\
 	print_testname(desc);					\
 	dotest(name##_spin, FAILURE, LOCKTYPE_SPIN);		\
@@ -1289,6 +1562,22 @@ static inline void print_testname(const char *testname)
 	DO_TESTCASE_2IB(desc, name, 312);			\
 	DO_TESTCASE_2IB(desc, name, 321);
 
+#define DO_TESTCASE_6x1RR(desc, name)				\
+	DO_TESTCASE_1RR(desc, name, 123);			\
+	DO_TESTCASE_1RR(desc, name, 132);			\
+	DO_TESTCASE_1RR(desc, name, 213);			\
+	DO_TESTCASE_1RR(desc, name, 231);			\
+	DO_TESTCASE_1RR(desc, name, 312);			\
+	DO_TESTCASE_1RR(desc, name, 321);
+
+#define DO_TESTCASE_6x1RRB(desc, name)				\
+	DO_TESTCASE_1RRB(desc, name, 123);			\
+	DO_TESTCASE_1RRB(desc, name, 132);			\
+	DO_TESTCASE_1RRB(desc, name, 213);			\
+	DO_TESTCASE_1RRB(desc, name, 231);			\
+	DO_TESTCASE_1RRB(desc, name, 312);			\
+	DO_TESTCASE_1RRB(desc, name, 321);
+
 #define DO_TESTCASE_6x6(desc, name)				\
 	DO_TESTCASE_6I(desc, name, 123);			\
 	DO_TESTCASE_6I(desc, name, 132);			\
@@ -1966,6 +2255,108 @@ static void ww_tests(void)
 	pr_cont("\n");
 }
 
+
+/*
+ * <in hardirq handler>
+ * read_lock(&A);
+ *			<hardirq disable>
+ *			spin_lock(&B);
+ * spin_lock(&B);
+ *			read_lock(&A);
+ *
+ * is a deadlock.
+ */
+static void queued_read_lock_hardirq_RE_Er(void)
+{
+	HARDIRQ_ENTER();
+	read_lock(&rwlock_A);
+	LOCK(B);
+	UNLOCK(B);
+	read_unlock(&rwlock_A);
+	HARDIRQ_EXIT();
+
+	HARDIRQ_DISABLE();
+	LOCK(B);
+	read_lock(&rwlock_A);
+	read_unlock(&rwlock_A);
+	UNLOCK(B);
+	HARDIRQ_ENABLE();
+}
+
+/*
+ * <in hardirq handler>
+ * spin_lock(&B);
+ *			<hardirq disable>
+ *			read_lock(&A);
+ * read_lock(&A);
+ *			spin_lock(&B);
+ *
+ * is not a deadlock.
+ */
+static void queued_read_lock_hardirq_ER_rE(void)
+{
+	HARDIRQ_ENTER();
+	LOCK(B);
+	read_lock(&rwlock_A);
+	read_unlock(&rwlock_A);
+	UNLOCK(B);
+	HARDIRQ_EXIT();
+
+	HARDIRQ_DISABLE();
+	read_lock(&rwlock_A);
+	LOCK(B);
+	UNLOCK(B);
+	read_unlock(&rwlock_A);
+	HARDIRQ_ENABLE();
+}
+
+/*
+ * <hardirq disable>
+ * spin_lock(&B);
+ *			read_lock(&A);
+ *			<in hardirq handler>
+ *			spin_lock(&B);
+ * read_lock(&A);
+ *
+ * is a deadlock. Because the two read_lock()s are both non-recursive readers.
+ */
+static void queued_read_lock_hardirq_inversion(void)
+{
+
+	HARDIRQ_ENTER();
+	LOCK(B);
+	UNLOCK(B);
+	HARDIRQ_EXIT();
+
+	HARDIRQ_DISABLE();
+	LOCK(B);
+	read_lock(&rwlock_A);
+	read_unlock(&rwlock_A);
+	UNLOCK(B);
+	HARDIRQ_ENABLE();
+
+	read_lock(&rwlock_A);
+	read_unlock(&rwlock_A);
+}
+
+static void queued_read_lock_tests(void)
+{
+	printk("  --------------------------------------------------------------------------\n");
+	printk("  | queued read lock tests |\n");
+	printk("  ---------------------------\n");
+	print_testname("hardirq read-lock/lock-read");
+	dotest(queued_read_lock_hardirq_RE_Er, FAILURE, LOCKTYPE_RWLOCK);
+	pr_cont("\n");
+
+	print_testname("hardirq lock-read/read-lock");
+	dotest(queued_read_lock_hardirq_ER_rE, SUCCESS, LOCKTYPE_RWLOCK);
+	pr_cont("\n");
+
+	print_testname("hardirq inversion");
+	dotest(queued_read_lock_hardirq_inversion, FAILURE, LOCKTYPE_RWLOCK);
+	pr_cont("\n");
+}
+
 void locking_selftest(void)
 {
 	/*
@@ -1979,6 +2370,11 @@ void locking_selftest(void)
 	}
 
 	/*
+	 * treats read_lock() as recursive read locks for testing purpose
+	 */
+	force_read_lock_recursive = 1;
+
+	/*
 	 * Run the testsuite:
 	 */
 	printk("------------------------\n");
@@ -2033,14 +2429,6 @@ void locking_selftest(void)
 	print_testname("mixed read-lock/lock-write ABBA");
 	pr_cont("             |");
 	dotest(rlock_ABBA1, FAILURE, LOCKTYPE_RWLOCK);
-#ifdef CONFIG_PROVE_LOCKING
-	/*
-	 * Lockdep does indeed fail here, but there's nothing we can do about
-	 * that now.  Don't kill lockdep for it.
-	 */
-	unexpected_testcase_failures--;
-#endif
-
 	pr_cont("             |");
 	dotest(rwsem_ABBA1, FAILURE, LOCKTYPE_RWSEM);
 
@@ -2056,6 +2444,15 @@ void locking_selftest(void)
 	pr_cont("             |");
 	dotest(rwsem_ABBA3, FAILURE, LOCKTYPE_RWSEM);
 
+	print_testname("chain cached mixed R-L/L-W ABBA");
+	pr_cont("             |");
+	dotest(rlock_chaincache_ABBA1, FAILURE, LOCKTYPE_RWLOCK);
+
+	DO_TESTCASE_6x1RRB("rlock W1R2/W2R3/W3R1", W1R2_W2R3_W3R1);
+	DO_TESTCASE_6x1RRB("rlock W1W2/R2R3/W3R1", W1W2_R2R3_W3R1);
+	DO_TESTCASE_6x1RR("rlock W1W2/R2R3/R3W1", W1W2_R2R3_R3W1);
+	DO_TESTCASE_6x1RR("rlock W1R2/R2R3/W3W1", W1R2_R2R3_W3W1);
+
 	printk("  --------------------------------------------------------------------------\n");
 
 	/*
@@ -2068,11 +2465,19 @@ void locking_selftest(void)
 	DO_TESTCASE_6x6("safe-A + unsafe-B #2", irqsafe4);
 	DO_TESTCASE_6x6RW("irq lock-inversion", irq_inversion);
 
-	DO_TESTCASE_6x2("irq read-recursion", irq_read_recursion);
-//	DO_TESTCASE_6x2B("irq read-recursion #2", irq_read_recursion2);
+	DO_TESTCASE_6x2x2RW("irq read-recursion", irq_read_recursion);
+	DO_TESTCASE_6x2x2RW("irq read-recursion #2", irq_read_recursion2);
+	DO_TESTCASE_6x2x2RW("irq read-recursion #3", irq_read_recursion3);
 
 	ww_tests();
 
+	force_read_lock_recursive = 0;
+	/*
+	 * queued_read_lock() specific test cases can be put here
+	 */
+	if (IS_ENABLED(CONFIG_QUEUED_RWLOCKS))
+		queued_read_lock_tests();
+
 	if (unexpected_testcase_failures) {
 		printk("-----------------------------------------------------------------\n");
 		debug_locks = 0;