Merge tag 'locking-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:

 - Introduce cmpxchg128() -- aka. the demise of cmpxchg_double()

   The cmpxchg128() family of functions is basically & functionally the
   same as cmpxchg_double(), but with a saner interface.

   Instead of a 6-parameter horror that forced u128 - u64/u64-halves
   layout details on the interface and exposed users to complexity,
   fragility & bugs, use a natural 3-parameter interface with u128
   types.

 - Restructure the generated atomic headers, and add kerneldoc comments
   for all of the generic atomic{,64,_long}_t operations.

   The generated definitions are much cleaner now, and come with
   documentation.

 - Implement lock_set_cmp_fn() on lockdep, for defining an ordering when
   taking multiple locks of the same type.

   This gets rid of one use of lockdep_set_novalidate_class() in the
   bcache code.

 - Fix raw_cpu_generic_try_cmpxchg() bug due to an unintended variable
   shadowing generating garbage code on Clang on certain ARM builds.

* tag 'locking-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
  locking/atomic: scripts: fix ${atomic}_dec_if_positive() kerneldoc
  percpu: Fix self-assignment of __old in raw_cpu_generic_try_cmpxchg()
  locking/atomic: treewide: delete arch_atomic_*() kerneldoc
  locking/atomic: docs: Add atomic operations to the driver basic API documentation
  locking/atomic: scripts: generate kerneldoc comments
  docs: scripts: kernel-doc: accept bitwise negation like ~@var
  locking/atomic: scripts: simplify raw_atomic*() definitions
  locking/atomic: scripts: simplify raw_atomic_long*() definitions
  locking/atomic: scripts: split pfx/name/sfx/order
  locking/atomic: scripts: restructure fallback ifdeffery
  locking/atomic: scripts: build raw_atomic_long*() directly
  locking/atomic: treewide: use raw_atomic*_<op>()
  locking/atomic: scripts: add trivial raw_atomic*_<op>()
  locking/atomic: scripts: factor out order template generation
  locking/atomic: scripts: remove leftover "${mult}"
  locking/atomic: scripts: remove bogus order parameter
  locking/atomic: xtensa: add preprocessor symbols
  locking/atomic: x86: add preprocessor symbols
  locking/atomic: sparc: add preprocessor symbols
  locking/atomic: sh: add preprocessor symbols
  ...

1 files changed, 87 insertions, 31 deletions

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 4dfd2f3e09b2..111607d91489 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -709,7 +709,7 @@ void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
 	usage[i] = '\0';
 }
 
-static void __print_lock_name(struct lock_class *class)
+static void __print_lock_name(struct held_lock *hlock, struct lock_class *class)
 {
 	char str[KSYM_NAME_LEN];
 	const char *name;
@@ -724,17 +724,19 @@ static void __print_lock_name(struct lock_class *class)
 			printk(KERN_CONT "#%d", class->name_version);
 		if (class->subclass)
 			printk(KERN_CONT "/%d", class->subclass);
+		if (hlock && class->print_fn)
+			class->print_fn(hlock->instance);
 	}
 }
 
-static void print_lock_name(struct lock_class *class)
+static void print_lock_name(struct held_lock *hlock, struct lock_class *class)
 {
 	char usage[LOCK_USAGE_CHARS];
 
 	get_usage_chars(class, usage);
 
 	printk(KERN_CONT " (");
-	__print_lock_name(class);
+	__print_lock_name(hlock, class);
 	printk(KERN_CONT "){%s}-{%d:%d}", usage,
 			class->wait_type_outer ?: class->wait_type_inner,
 			class->wait_type_inner);
@@ -772,7 +774,7 @@ static void print_lock(struct held_lock *hlock)
 	}
 
 	printk(KERN_CONT "%px", hlock->instance);
-	print_lock_name(lock);
+	print_lock_name(hlock, lock);
 	printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
 }
 
@@ -1868,7 +1870,7 @@ print_circular_bug_entry(struct lock_list *target, int depth)
 	if (debug_locks_silent)
 		return;
 	printk("\n-> #%u", depth);
-	print_lock_name(target->class);
+	print_lock_name(NULL, target->class);
 	printk(KERN_CONT ":\n");
 	print_lock_trace(target->trace, 6);
 }
@@ -1899,11 +1901,11 @@ print_circular_lock_scenario(struct held_lock *src,
 	 */
 	if (parent != source) {
 		printk("Chain exists of:\n  ");
-		__print_lock_name(source);
+		__print_lock_name(src, source);
 		printk(KERN_CONT " --> ");
-		__print_lock_name(parent);
+		__print_lock_name(NULL, parent);
 		printk(KERN_CONT " --> ");
-		__print_lock_name(target);
+		__print_lock_name(tgt, target);
 		printk(KERN_CONT "\n\n");
 	}
 
@@ -1914,13 +1916,13 @@ print_circular_lock_scenario(struct held_lock *src,
 		printk("  rlock(");
 	else
 		printk("  lock(");
-	__print_lock_name(target);
+	__print_lock_name(tgt, target);
 	printk(KERN_CONT ");\n");
 	printk("                               lock(");
-	__print_lock_name(parent);
+	__print_lock_name(NULL, parent);
 	printk(KERN_CONT ");\n");
 	printk("                               lock(");
-	__print_lock_name(target);
+	__print_lock_name(tgt, target);
 	printk(KERN_CONT ");\n");
 	if (src_read != 0)
 		printk("  rlock(");
@@ -1928,7 +1930,7 @@ print_circular_lock_scenario(struct held_lock *src,
 		printk("  sync(");
 	else
 		printk("  lock(");
-	__print_lock_name(source);
+	__print_lock_name(src, source);
 	printk(KERN_CONT ");\n");
 	printk("\n *** DEADLOCK ***\n\n");
 }
@@ -2154,6 +2156,8 @@ check_path(struct held_lock *target, struct lock_list *src_entry,
 	return ret;
 }
 
+static void print_deadlock_bug(struct task_struct *, struct held_lock *, struct held_lock *);
+
 /*
  * Prove that the dependency graph starting at <src> can not
  * lead to <target>. If it can, there is a circle when adding
@@ -2185,7 +2189,10 @@ check_noncircular(struct held_lock *src, struct held_lock *target,
 			*trace = save_trace();
 		}
 
-		print_circular_bug(&src_entry, target_entry, src, target);
+		if (src->class_idx == target->class_idx)
+			print_deadlock_bug(current, src, target);
+		else
+			print_circular_bug(&src_entry, target_entry, src, target);
 	}
 
 	return ret;
@@ -2346,7 +2353,7 @@ static void print_lock_class_header(struct lock_class *class, int depth)
 	int bit;
 
 	printk("%*s->", depth, "");
-	print_lock_name(class);
+	print_lock_name(NULL, class);
 #ifdef CONFIG_DEBUG_LOCKDEP
 	printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
 #endif
@@ -2528,11 +2535,11 @@ print_irq_lock_scenario(struct lock_list *safe_entry,
 	 */
 	if (middle_class != unsafe_class) {
 		printk("Chain exists of:\n  ");
-		__print_lock_name(safe_class);
+		__print_lock_name(NULL, safe_class);
 		printk(KERN_CONT " --> ");
-		__print_lock_name(middle_class);
+		__print_lock_name(NULL, middle_class);
 		printk(KERN_CONT " --> ");
-		__print_lock_name(unsafe_class);
+		__print_lock_name(NULL, unsafe_class);
 		printk(KERN_CONT "\n\n");
 	}
 
@@ -2540,18 +2547,18 @@ print_irq_lock_scenario(struct lock_list *safe_entry,
 	printk("       CPU0                    CPU1\n");
 	printk("       ----                    ----\n");
 	printk("  lock(");
-	__print_lock_name(unsafe_class);
+	__print_lock_name(NULL, unsafe_class);
 	printk(KERN_CONT ");\n");
 	printk("                               local_irq_disable();\n");
 	printk("                               lock(");
-	__print_lock_name(safe_class);
+	__print_lock_name(NULL, safe_class);
 	printk(KERN_CONT ");\n");
 	printk("                               lock(");
-	__print_lock_name(middle_class);
+	__print_lock_name(NULL, middle_class);
 	printk(KERN_CONT ");\n");
 	printk("  <Interrupt>\n");
 	printk("    lock(");
-	__print_lock_name(safe_class);
+	__print_lock_name(NULL, safe_class);
 	printk(KERN_CONT ");\n");
 	printk("\n *** DEADLOCK ***\n\n");
 }
@@ -2588,20 +2595,20 @@ print_bad_irq_dependency(struct task_struct *curr,
 	pr_warn("\nand this task is already holding:\n");
 	print_lock(prev);
 	pr_warn("which would create a new lock dependency:\n");
-	print_lock_name(hlock_class(prev));
+	print_lock_name(prev, hlock_class(prev));
 	pr_cont(" ->");
-	print_lock_name(hlock_class(next));
+	print_lock_name(next, hlock_class(next));
 	pr_cont("\n");
 
 	pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
 		irqclass);
-	print_lock_name(backwards_entry->class);
+	print_lock_name(NULL, backwards_entry->class);
 	pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
 
 	print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
 
 	pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
-	print_lock_name(forwards_entry->class);
+	print_lock_name(NULL, forwards_entry->class);
 	pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
 	pr_warn("...");
 
@@ -2971,10 +2978,10 @@ print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
 	printk("       CPU0\n");
 	printk("       ----\n");
 	printk("  lock(");
-	__print_lock_name(prev);
+	__print_lock_name(prv, prev);
 	printk(KERN_CONT ");\n");
 	printk("  lock(");
-	__print_lock_name(next);
+	__print_lock_name(nxt, next);
 	printk(KERN_CONT ");\n");
 	printk("\n *** DEADLOCK ***\n\n");
 	printk(" May be due to missing lock nesting notation\n\n");
@@ -2984,6 +2991,8 @@ static void
 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
 		   struct held_lock *next)
 {
+	struct lock_class *class = hlock_class(prev);
+
 	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
 		return;
 
@@ -2998,6 +3007,11 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
 	pr_warn("\nbut task is already holding lock:\n");
 	print_lock(prev);
 
+	if (class->cmp_fn) {
+		pr_warn("and the lock comparison function returns %i:\n",
+			class->cmp_fn(prev->instance, next->instance));
+	}
+
 	pr_warn("\nother info that might help us debug this:\n");
 	print_deadlock_scenario(next, prev);
 	lockdep_print_held_locks(curr);
@@ -3019,6 +3033,7 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
 static int
 check_deadlock(struct task_struct *curr, struct held_lock *next)
 {
+	struct lock_class *class;
 	struct held_lock *prev;
 	struct held_lock *nest = NULL;
 	int i;
@@ -3039,6 +3054,12 @@ check_deadlock(struct task_struct *curr, struct held_lock *next)
 		if ((next->read == 2) && prev->read)
 			continue;
 
+		class = hlock_class(prev);
+
+		if (class->cmp_fn &&
+		    class->cmp_fn(prev->instance, next->instance) < 0)
+			continue;
+
 		/*
 		 * We're holding the nest_lock, which serializes this lock's
 		 * nesting behaviour.
@@ -3100,6 +3121,14 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
 		return 2;
 	}
 
+	if (prev->class_idx == next->class_idx) {
+		struct lock_class *class = hlock_class(prev);
+
+		if (class->cmp_fn &&
+		    class->cmp_fn(prev->instance, next->instance) < 0)
+			return 2;
+	}
+
 	/*
 	 * Prove that the new <prev> -> <next> dependency would not
 	 * create a circular dependency in the graph. (We do this by
@@ -3576,7 +3605,7 @@ static void print_chain_keys_chain(struct lock_chain *chain)
 		hlock_id = chain_hlocks[chain->base + i];
 		chain_key = print_chain_key_iteration(hlock_id, chain_key);
 
-		print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id));
+		print_lock_name(NULL, lock_classes + chain_hlock_class_idx(hlock_id));
 		printk("\n");
 	}
 }
@@ -3933,11 +3962,11 @@ static void print_usage_bug_scenario(struct held_lock *lock)
 	printk("       CPU0\n");
 	printk("       ----\n");
 	printk("  lock(");
-	__print_lock_name(class);
+	__print_lock_name(lock, class);
 	printk(KERN_CONT ");\n");
 	printk("  <Interrupt>\n");
 	printk("    lock(");
-	__print_lock_name(class);
+	__print_lock_name(lock, class);
 	printk(KERN_CONT ");\n");
 	printk("\n *** DEADLOCK ***\n\n");
 }
@@ -4023,7 +4052,7 @@ print_irq_inversion_bug(struct task_struct *curr,
 		pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
 	else
 		pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
-	print_lock_name(other->class);
+	print_lock_name(NULL, other->class);
 	pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
 
 	pr_warn("\nother info that might help us debug this:\n");
@@ -4896,6 +4925,33 @@ EXPORT_SYMBOL_GPL(lockdep_init_map_type);
 struct lock_class_key __lockdep_no_validate__;
 EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
 
+#ifdef CONFIG_PROVE_LOCKING
+void lockdep_set_lock_cmp_fn(struct lockdep_map *lock, lock_cmp_fn cmp_fn,
+			     lock_print_fn print_fn)
+{
+	struct lock_class *class = lock->class_cache[0];
+	unsigned long flags;
+
+	raw_local_irq_save(flags);
+	lockdep_recursion_inc();
+
+	if (!class)
+		class = register_lock_class(lock, 0, 0);
+
+	if (class) {
+		WARN_ON(class->cmp_fn	&& class->cmp_fn != cmp_fn);
+		WARN_ON(class->print_fn && class->print_fn != print_fn);
+
+		class->cmp_fn	= cmp_fn;
+		class->print_fn = print_fn;
+	}
+
+	lockdep_recursion_finish();
+	raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lockdep_set_lock_cmp_fn);
+#endif
+
 static void
 print_lock_nested_lock_not_held(struct task_struct *curr,
 				struct held_lock *hlock)