Date:   Thu, 25 May 2017 14:59:42 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, bobby.prani@...il.com,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 69/88] lockdep: Use consistent printing primitives

Commit a5dd63efda3d ("lockdep: Use "WARNING" tag on lockdep splats")
substituted pr_warn() for printk() in places called out by Dmitry Vyukov.
However, this resulted in an ugly mix of pr_warn() and printk().  This
commit therefore changes printk() to pr_warn() or pr_cont(), depending
on the absence or presence of KERN_CONT.  This is done in all functions
that had printk() changed to pr_warn() by the aforementioned commit.

Reported-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/locking/lockdep.c | 172 +++++++++++++++++++++++------------------------
 1 file changed, 86 insertions(+), 86 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c0e31bfee25c..cceb9534338a 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1157,18 +1157,18 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth,
 	if (debug_locks_silent)
 		return 0;
 
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("======================================================\n");
 	pr_warn("WARNING: possible circular locking dependency detected\n");
 	print_kernel_ident();
 	pr_warn("------------------------------------------------------\n");
-	printk("%s/%d is trying to acquire lock:\n",
+	pr_warn("%s/%d is trying to acquire lock:\n",
 		curr->comm, task_pid_nr(curr));
 	print_lock(check_src);
-	printk("\nbut task is already holding lock:\n");
+	pr_warn("\nbut task is already holding lock:\n");
 	print_lock(check_tgt);
-	printk("\nwhich lock already depends on the new lock.\n\n");
-	printk("\nthe existing dependency chain (in reverse order) is:\n");
+	pr_warn("\nwhich lock already depends on the new lock.\n\n");
+	pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
 
 	print_circular_bug_entry(entry, depth);
 
@@ -1495,13 +1495,13 @@ print_bad_irq_dependency(struct task_struct *curr,
 	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
 		return 0;
 
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("=====================================================\n");
 	pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
 		irqclass, irqclass);
 	print_kernel_ident();
 	pr_warn("-----------------------------------------------------\n");
-	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
+	pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
 		curr->comm, task_pid_nr(curr),
 		curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
 		curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
@@ -1509,46 +1509,46 @@ print_bad_irq_dependency(struct task_struct *curr,
 		curr->softirqs_enabled);
 	print_lock(next);
 
-	printk("\nand this task is already holding:\n");
+	pr_warn("\nand this task is already holding:\n");
 	print_lock(prev);
-	printk("which would create a new lock dependency:\n");
+	pr_warn("which would create a new lock dependency:\n");
 	print_lock_name(hlock_class(prev));
-	printk(KERN_CONT " ->");
+	pr_cont(" ->");
 	print_lock_name(hlock_class(next));
-	printk(KERN_CONT "\n");
+	pr_cont("\n");
 
-	printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
+	pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
 		irqclass);
 	print_lock_name(backwards_entry->class);
-	printk("\n... which became %s-irq-safe at:\n", irqclass);
+	pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
 
 	print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
 
-	printk("\nto a %s-irq-unsafe lock:\n", irqclass);
+	pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
 	print_lock_name(forwards_entry->class);
-	printk("\n... which became %s-irq-unsafe at:\n", irqclass);
-	printk("...");
+	pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
+	pr_warn("...");
 
 	print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
 
-	printk("\nother info that might help us debug this:\n\n");
+	pr_warn("\nother info that might help us debug this:\n\n");
 	print_irq_lock_scenario(backwards_entry, forwards_entry,
 				hlock_class(prev), hlock_class(next));
 
 	lockdep_print_held_locks(curr);
 
-	printk("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
+	pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
 	if (!save_trace(&prev_root->trace))
 		return 0;
 	print_shortest_lock_dependencies(backwards_entry, prev_root);
 
-	printk("\nthe dependencies between the lock to be acquired");
-	printk(" and %s-irq-unsafe lock:\n", irqclass);
+	pr_warn("\nthe dependencies between the lock to be acquired");
+	pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
 	if (!save_trace(&next_root->trace))
 		return 0;
 	print_shortest_lock_dependencies(forwards_entry, next_root);
 
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 
 	return 0;
@@ -1724,22 +1724,22 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
 	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
 		return 0;
 
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("============================================\n");
 	pr_warn("WARNING: possible recursive locking detected\n");
 	print_kernel_ident();
 	pr_warn("--------------------------------------------\n");
-	printk("%s/%d is trying to acquire lock:\n",
+	pr_warn("%s/%d is trying to acquire lock:\n",
 		curr->comm, task_pid_nr(curr));
 	print_lock(next);
-	printk("\nbut task is already holding lock:\n");
+	pr_warn("\nbut task is already holding lock:\n");
 	print_lock(prev);
 
-	printk("\nother info that might help us debug this:\n");
+	pr_warn("\nother info that might help us debug this:\n");
 	print_deadlock_scenario(next, prev);
 	lockdep_print_held_locks(curr);
 
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 
 	return 0;
@@ -2074,21 +2074,21 @@ static void print_collision(struct task_struct *curr,
 			struct held_lock *hlock_next,
 			struct lock_chain *chain)
 {
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("============================\n");
 	pr_warn("WARNING: chain_key collision\n");
 	print_kernel_ident();
 	pr_warn("----------------------------\n");
-	printk("%s/%d: ", current->comm, task_pid_nr(current));
-	printk("Hash chain already cached but the contents don't match!\n");
+	pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
+	pr_warn("Hash chain already cached but the contents don't match!\n");
 
-	printk("Held locks:");
+	pr_warn("Held locks:");
 	print_chain_keys_held_locks(curr, hlock_next);
 
-	printk("Locks in cached chain:");
+	pr_warn("Locks in cached chain:");
 	print_chain_keys_chain(chain);
 
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 }
 #endif
@@ -2373,16 +2373,16 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this,
 	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
 		return 0;
 
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("================================\n");
 	pr_warn("WARNING: inconsistent lock state\n");
 	print_kernel_ident();
 	pr_warn("--------------------------------\n");
 
-	printk("inconsistent {%s} -> {%s} usage.\n",
+	pr_warn("inconsistent {%s} -> {%s} usage.\n",
 		usage_str[prev_bit], usage_str[new_bit]);
 
-	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
+	pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
 		curr->comm, task_pid_nr(curr),
 		trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
 		trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
@@ -2390,16 +2390,16 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this,
 		trace_softirqs_enabled(curr));
 	print_lock(this);
 
-	printk("{%s} state was registered at:\n", usage_str[prev_bit]);
+	pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
 	print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
 
 	print_irqtrace_events(curr);
-	printk("\nother info that might help us debug this:\n");
+	pr_warn("\nother info that might help us debug this:\n");
 	print_usage_bug_scenario(this);
 
 	lockdep_print_held_locks(curr);
 
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 
 	return 0;
@@ -2438,28 +2438,28 @@ print_irq_inversion_bug(struct task_struct *curr,
 	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
 		return 0;
 
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("========================================================\n");
 	pr_warn("WARNING: possible irq lock inversion dependency detected\n");
 	print_kernel_ident();
 	pr_warn("--------------------------------------------------------\n");
-	printk("%s/%d just changed the state of lock:\n",
+	pr_warn("%s/%d just changed the state of lock:\n",
 		curr->comm, task_pid_nr(curr));
 	print_lock(this);
 	if (forwards)
-		printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
+		pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
 	else
-		printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
+		pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
 	print_lock_name(other->class);
-	printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
+	pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
 
-	printk("\nother info that might help us debug this:\n");
+	pr_warn("\nother info that might help us debug this:\n");
 
 	/* Find a middle lock (if one exists) */
 	depth = get_lock_depth(other);
 	do {
 		if (depth == 0 && (entry != root)) {
-			printk("lockdep:%s bad path found in chain graph\n", __func__);
+			pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
 			break;
 		}
 		middle = entry;
@@ -2475,12 +2475,12 @@ print_irq_inversion_bug(struct task_struct *curr,
 
 	lockdep_print_held_locks(curr);
 
-	printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
+	pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
 	if (!save_trace(&root->trace))
 		return 0;
 	print_shortest_lock_dependencies(other, root);
 
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 
 	return 0;
@@ -3189,25 +3189,25 @@ print_lock_nested_lock_not_held(struct task_struct *curr,
 	if (debug_locks_silent)
 		return 0;
 
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("==================================\n");
 	pr_warn("WARNING: Nested lock was not taken\n");
 	print_kernel_ident();
 	pr_warn("----------------------------------\n");
 
-	printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
+	pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
 	print_lock(hlock);
 
-	printk("\nbut this task is not holding:\n");
-	printk("%s\n", hlock->nest_lock->name);
+	pr_warn("\nbut this task is not holding:\n");
+	pr_warn("%s\n", hlock->nest_lock->name);
 
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 
-	printk("\nother info that might help us debug this:\n");
+	pr_warn("\nother info that might help us debug this:\n");
 	lockdep_print_held_locks(curr);
 
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 
 	return 0;
@@ -3402,21 +3402,21 @@ print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
 	if (debug_locks_silent)
 		return 0;
 
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("=====================================\n");
 	pr_warn("WARNING: bad unlock balance detected!\n");
 	print_kernel_ident();
 	pr_warn("-------------------------------------\n");
-	printk("%s/%d is trying to release lock (",
+	pr_warn("%s/%d is trying to release lock (",
 		curr->comm, task_pid_nr(curr));
 	print_lockdep_cache(lock);
-	printk(KERN_CONT ") at:\n");
+	pr_cont(") at:\n");
 	print_ip_sym(ip);
-	printk("but there are no more locks to release!\n");
-	printk("\nother info that might help us debug this:\n");
+	pr_warn("but there are no more locks to release!\n");
+	pr_warn("\nother info that might help us debug this:\n");
 	lockdep_print_held_locks(curr);
 
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 
 	return 0;
@@ -3974,21 +3974,21 @@ print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
 	if (debug_locks_silent)
 		return 0;
 
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("=================================\n");
 	pr_warn("WARNING: bad contention detected!\n");
 	print_kernel_ident();
 	pr_warn("---------------------------------\n");
-	printk("%s/%d is trying to contend lock (",
+	pr_warn("%s/%d is trying to contend lock (",
 		curr->comm, task_pid_nr(curr));
 	print_lockdep_cache(lock);
-	printk(KERN_CONT ") at:\n");
+	pr_cont(") at:\n");
 	print_ip_sym(ip);
-	printk("but there are no locks held!\n");
-	printk("\nother info that might help us debug this:\n");
+	pr_warn("but there are no locks held!\n");
+	pr_warn("\nother info that might help us debug this:\n");
 	lockdep_print_held_locks(curr);
 
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 
 	return 0;
@@ -4318,17 +4318,17 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
 	if (debug_locks_silent)
 		return;
 
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("=========================\n");
 	pr_warn("WARNING: held lock freed!\n");
 	print_kernel_ident();
 	pr_warn("-------------------------\n");
-	printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
+	pr_warn("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
 		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
 	print_lock(hlock);
 	lockdep_print_held_locks(curr);
 
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 }
 
@@ -4376,14 +4376,14 @@ static void print_held_locks_bug(void)
 	if (debug_locks_silent)
 		return;
 
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("====================================\n");
 	pr_warn("WARNING: %s/%d still has locks held!\n",
 	       current->comm, task_pid_nr(current));
 	print_kernel_ident();
 	pr_warn("------------------------------------\n");
 	lockdep_print_held_locks(current);
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 }
 
@@ -4402,10 +4402,10 @@ void debug_show_all_locks(void)
 	int unlock = 1;
 
 	if (unlikely(!debug_locks)) {
-		printk("INFO: lockdep is turned off.\n");
+		pr_warn("INFO: lockdep is turned off.\n");
 		return;
 	}
-	printk("\nShowing all locks held in the system:\n");
+	pr_warn("\nShowing all locks held in the system:\n");
 
 	/*
 	 * Here we try to get the tasklist_lock as hard as possible,
@@ -4416,18 +4416,18 @@ void debug_show_all_locks(void)
 retry:
 	if (!read_trylock(&tasklist_lock)) {
 		if (count == 10)
-			printk("hm, tasklist_lock locked, retrying... ");
+			pr_warn("hm, tasklist_lock locked, retrying... ");
 		if (count) {
 			count--;
-			printk(" #%d", 10-count);
+			pr_cont(" #%d", 10-count);
 			mdelay(200);
 			goto retry;
 		}
-		printk(" ignoring it.\n");
+		pr_cont(" ignoring it.\n");
 		unlock = 0;
 	} else {
 		if (count != 10)
-			printk(KERN_CONT " locked it.\n");
+			pr_cont(" locked it.\n");
 	}
 
 	do_each_thread(g, p) {
@@ -4445,7 +4445,7 @@ void debug_show_all_locks(void)
 				unlock = 1;
 	} while_each_thread(g, p);
 
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("=============================================\n\n");
 
 	if (unlock)
@@ -4475,12 +4475,12 @@ asmlinkage __visible void lockdep_sys_exit(void)
 	if (unlikely(curr->lockdep_depth)) {
 		if (!debug_locks_off())
 			return;
-		printk("\n");
+		pr_warn("\n");
 		pr_warn("================================================\n");
 		pr_warn("WARNING: lock held when returning to user space!\n");
 		print_kernel_ident();
 		pr_warn("------------------------------------------------\n");
-		printk("%s/%d is leaving the kernel with locks still held!\n",
+		pr_warn("%s/%d is leaving the kernel with locks still held!\n",
 				curr->comm, curr->pid);
 		lockdep_print_held_locks(curr);
 	}
@@ -4495,14 +4495,14 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
 		return;
 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
 	/* Note: the following can be executed concurrently, so be careful. */
-	printk("\n");
+	pr_warn("\n");
 	pr_warn("=============================\n");
 	pr_warn("WARNING: suspicious RCU usage\n");
 	print_kernel_ident();
 	pr_warn("-----------------------------\n");
-	printk("%s:%d %s!\n", file, line, s);
-	printk("\nother info that might help us debug this:\n\n");
-	printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
+	pr_warn("%s:%d %s!\n", file, line, s);
+	pr_warn("\nother info that might help us debug this:\n\n");
+	pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
 	       !rcu_lockdep_current_cpu_online()
 			? "RCU used illegally from offline CPU!\n"
 			: !rcu_is_watching()
@@ -4529,10 +4529,10 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
 	 * rcu_read_lock_bh() and so on from extended quiescent states.
 	 */
 	if (!rcu_is_watching())
-		printk("RCU used illegally from extended quiescent state!\n");
+		pr_warn("RCU used illegally from extended quiescent state!\n");
 
 	lockdep_print_held_locks(curr);
-	printk("\nstack backtrace:\n");
+	pr_warn("\nstack backtrace:\n");
 	dump_stack();
 }
 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
-- 
2.5.2

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