Merge tag 'locking-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:

 - rtmutex cleanup & spring cleaning pass that removes ~400 lines of
   code

 - Futex simplifications & cleanups

 - Add debugging to the CSD code, to help track down a tenacious race
   (or hw problem)

 - Add lockdep_assert_not_held(), to allow code to require a lock to not
   be held, and propagate this into the ath10k driver

 - Misc LKMM documentation updates

 - Misc KCSAN updates: cleanups & documentation updates

 - Misc fixes and cleanups

 - Fix locktorture bugs with ww_mutexes

* tag 'locking-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
  kcsan: Fix printk format string
  static_call: Relax static_call_update() function argument type
  static_call: Fix unused variable warn w/o MODULE
  locking/rtmutex: Clean up signal handling in __rt_mutex_slowlock()
  locking/rtmutex: Restrict the trylock WARN_ON() to debug
  locking/rtmutex: Fix misleading comment in rt_mutex_postunlock()
  locking/rtmutex: Consolidate the fast/slowpath invocation
  locking/rtmutex: Make text section and inlining consistent
  locking/rtmutex: Move debug functions as inlines into common header
  locking/rtmutex: Decrapify __rt_mutex_init()
  locking/rtmutex: Remove pointless CONFIG_RT_MUTEXES=n stubs
  locking/rtmutex: Inline chainwalk depth check
  locking/rtmutex: Move rt_mutex_debug_task_free() to rtmutex.c
  locking/rtmutex: Remove empty and unused debug stubs
  locking/rtmutex: Consolidate rt_mutex_init()
  locking/rtmutex: Remove output from deadlock detector
  locking/rtmutex: Remove rtmutex deadlock tester leftovers
  locking/rtmutex: Remove rt_mutex_timed_lock()
  MAINTAINERS: Add myself as futex reviewer
  locking/mutex: Remove repeated declaration
  ...

Author: torvalds

Documentation/admin-guide/kernel-parameters.txt

@@ -782,6 +782,16 @@
 	cs89x0_media=	[HW,NET]
 			Format: { rj45 | aui | bnc }
 
+	csdlock_debug=	[KNL] Enable debug add-ons of cross-CPU function call
+			handling. When switched on, additional debug data is
+			printed to the console in case a hanging CPU is
+			detected, and that CPU is pinged again in order to try
+			to resolve the hang situation.
+			0: disable csdlock debugging (default)
+			1: enable basic csdlock debugging (minor impact)
+			ext: enable extended csdlock debugging (more impact,
+			     but more data)
+
 	dasd=		[HW,NET]
 			See header of drivers/s390/block/dasd_devmap.c.
 

Documentation/dev-tools/kcsan.rst

@@ -1,3 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. Copyright (C) 2019, Google LLC.
+
 The Kernel Concurrency Sanitizer (KCSAN)
 ========================================
 

MAINTAINERS

@@ -7452,6 +7452,7 @@ M:	Thomas Gleixner <tglx@linutronix.de>
 M:	Ingo Molnar <mingo@redhat.com>
 R:	Peter Zijlstra <peterz@infradead.org>
 R:	Darren Hart <dvhart@infradead.org>
+R:	Davidlohr Bueso <dave@stgolabs.net>
 L:	linux-kernel@vger.kernel.org
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git locking/core

arch/arm/include/asm/spinlock.h

@@ -22,7 +22,7 @@
  * assembler to insert a extra (16-bit) IT instruction, depending on the
  * presence or absence of neighbouring conditional instructions.
  *
- * To avoid this unpredictableness, an approprite IT is inserted explicitly:
+ * To avoid this unpredictability, an appropriate IT is inserted explicitly:
  * the assembler won't change IT instructions which are explicitly present
  * in the input.
  */

arch/x86/include/asm/jump_label.h

@@ -14,7 +14,7 @@
 #include <linux/stringify.h>
 #include <linux/types.h>
 
-static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
+static __always_inline bool arch_static_branch(struct static_key * const key, const bool branch)
 {
 	asm_volatile_goto("1:"
 		".byte " __stringify(BYTES_NOP5) "\n\t"
@@ -30,7 +30,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
 	return true;
 }
 
-static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
+static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
 {
 	asm_volatile_goto("1:"
 		".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t"

drivers/net/wireless/ath/ath10k/mac.c

@@ -4727,6 +4727,8 @@ static void ath10k_mac_op_wake_tx_queue(struct ieee80211_hw *hw,
 /* Must not be called with conf_mutex held as workers can use that also. */
 void ath10k_drain_tx(struct ath10k *ar)
 {
+	lockdep_assert_not_held(&ar->conf_mutex);
+
 	/* make sure rcu-protected mac80211 tx path itself is drained */
 	synchronize_net();
 

include/linux/kcsan-checks.h

@@ -1,4 +1,10 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KCSAN access checks and modifiers. These can be used to explicitly check
+ * uninstrumented accesses, or change KCSAN checking behaviour of accesses.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
 
 #ifndef _LINUX_KCSAN_CHECKS_H
 #define _LINUX_KCSAN_CHECKS_H

include/linux/kcsan.h

@@ -1,4 +1,11 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * The Kernel Concurrency Sanitizer (KCSAN) infrastructure. Public interface and
+ * data structures to set up runtime. See kcsan-checks.h for explicit checks and
+ * modifiers. For more info please see Documentation/dev-tools/kcsan.rst.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
 
 #ifndef _LINUX_KCSAN_H
 #define _LINUX_KCSAN_H

include/linux/lockdep.h

@@ -155,7 +155,7 @@ extern void lockdep_set_selftest_task(struct task_struct *task);
 extern void lockdep_init_task(struct task_struct *task);
 
 /*
- * Split the recrursion counter in two to readily detect 'off' vs recursion.
+ * Split the recursion counter in two to readily detect 'off' vs recursion.
  */
 #define LOCKDEP_RECURSION_BITS	16
 #define LOCKDEP_OFF		(1U << LOCKDEP_RECURSION_BITS)
@@ -268,6 +268,11 @@ extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 
 extern void lock_release(struct lockdep_map *lock, unsigned long ip);
 
+/* lock_is_held_type() returns */
+#define LOCK_STATE_UNKNOWN	-1
+#define LOCK_STATE_NOT_HELD	0
+#define LOCK_STATE_HELD		1
+
 /*
  * Same "read" as for lock_acquire(), except -1 means any.
  */
@@ -301,8 +306,14 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
 
 #define lockdep_depth(tsk)	(debug_locks ? (tsk)->lockdep_depth : 0)
 
-#define lockdep_assert_held(l)	do {				\
-		WARN_ON(debug_locks && !lockdep_is_held(l));	\
+#define lockdep_assert_held(l)	do {					\
+		WARN_ON(debug_locks &&					\
+			lockdep_is_held(l) == LOCK_STATE_NOT_HELD);	\
+	} while (0)
+
+#define lockdep_assert_not_held(l)	do {				\
+		WARN_ON(debug_locks &&					\
+			lockdep_is_held(l) == LOCK_STATE_HELD);		\
 	} while (0)
 
 #define lockdep_assert_held_write(l)	do {			\
@@ -397,7 +408,8 @@ extern int lockdep_is_held(const void *);
 #define lockdep_is_held_type(l, r)		(1)
 
 #define lockdep_assert_held(l)			do { (void)(l); } while (0)
-#define lockdep_assert_held_write(l)	do { (void)(l); } while (0)
+#define lockdep_assert_not_held(l)		do { (void)(l); } while (0)
+#define lockdep_assert_held_write(l)		do { (void)(l); } while (0)
 #define lockdep_assert_held_read(l)		do { (void)(l); } while (0)
 #define lockdep_assert_held_once(l)		do { (void)(l); } while (0)
 #define lockdep_assert_none_held_once()	do { } while (0)

include/linux/mutex.h

@@ -20,6 +20,7 @@
 #include <linux/osq_lock.h>
 #include <linux/debug_locks.h>
 
+struct ww_class;
 struct ww_acquire_ctx;
 
 /*
@@ -65,9 +66,6 @@ struct mutex {
 #endif
 };
 
-struct ww_class;
-struct ww_acquire_ctx;
-
 struct ww_mutex {
 	struct mutex base;
 	struct ww_acquire_ctx *ctx;