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Commit f6ec8829 authored by Yuyang Du's avatar Yuyang Du Committed by Ingo Molnar
Browse files

locking/lockdep: Define INITIAL_CHAIN_KEY for chain keys to start with 



Chain keys are computed using Jenkins hash function, which needs an initial
hash to start with. Dedicate a macro to make this clear and configurable. A
later patch changes this initial chain key.

Signed-off-by: default avatarYuyang Du <duyuyang@gmail.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bvanassche@acm.org
Cc: frederic@kernel.org
Cc: ming.lei@redhat.com
Cc: will.deacon@arm.com
Link: https://lkml.kernel.org/r/20190506081939.74287-9-duyuyang@gmail.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e196e479

include/linux/lockdep.h

+1 −0
Original line number Diff line number Diff line
@@ -229,6 +229,7 @@ struct lock_chain { 
 * bitfield and hitting the BUG in hlock_class().

 */

#define MAX_LOCKDEP_KEYS		((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)

#define INITIAL_CHAIN_KEY		0



struct held_lock {

	/*

init/init_task.c

+1 −1
Original line number Diff line number Diff line
@@ -167,7 +167,7 @@ struct task_struct init_task 
#endif

#ifdef CONFIG_LOCKDEP

	.lockdep_depth = 0, /* no locks held yet */

	.curr_chain_key = 0,

	.curr_chain_key = INITIAL_CHAIN_KEY,

	.lockdep_recursion = 0,

#endif

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

kernel/locking/lockdep.c

+9 −9
Original line number Diff line number Diff line
@@ -362,7 +362,7 @@ static inline u64 iterate_chain_key(u64 key, u32 idx) 
void lockdep_init_task(struct task_struct *task)

{

	task->lockdep_depth = 0; /* no locks held yet */

	task->curr_chain_key = 0;

	task->curr_chain_key = INITIAL_CHAIN_KEY;

	task->lockdep_recursion = 0;

}
@@ -857,7 +857,7 @@ static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; 
static bool check_lock_chain_key(struct lock_chain *chain)

{

#ifdef CONFIG_PROVE_LOCKING

	u64 chain_key = 0;

	u64 chain_key = INITIAL_CHAIN_KEY;

	int i;



	for (i = chain->base; i < chain->base + chain->depth; i++)
@@ -2524,7 +2524,7 @@ static void 
print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)

{

	struct held_lock *hlock;

	u64 chain_key = 0;

	u64 chain_key = INITIAL_CHAIN_KEY;

	int depth = curr->lockdep_depth;

	int i = get_first_held_lock(curr, hlock_next);
@@ -2544,7 +2544,7 @@ print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_ne 
static void print_chain_keys_chain(struct lock_chain *chain)

{

	int i;

	u64 chain_key = 0;

	u64 chain_key = INITIAL_CHAIN_KEY;

	int class_id;



	printk("depth: %u\n", chain->depth);
@@ -2848,7 +2848,7 @@ static void check_chain_key(struct task_struct *curr) 
#ifdef CONFIG_DEBUG_LOCKDEP

	struct held_lock *hlock, *prev_hlock = NULL;

	unsigned int i;

	u64 chain_key = 0;

	u64 chain_key = INITIAL_CHAIN_KEY;



	for (i = 0; i < curr->lockdep_depth; i++) {

		hlock = curr->held_locks + i;
@@ -2872,7 +2872,7 @@ static void check_chain_key(struct task_struct *curr) 


		if (prev_hlock && (prev_hlock->irq_context !=

							hlock->irq_context))

			chain_key = 0;

			chain_key = INITIAL_CHAIN_KEY;

		chain_key = iterate_chain_key(chain_key, hlock->class_idx);

		prev_hlock = hlock;

	}
@@ -3787,14 +3787,14 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, 
		/*

		 * How can we have a chain hash when we ain't got no keys?!

		 */

		if (DEBUG_LOCKS_WARN_ON(chain_key != 0))

		if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY))

			return 0;

		chain_head = 1;

	}



	hlock->prev_chain_key = chain_key;

	if (separate_irq_context(curr, hlock)) {

		chain_key = 0;

		chain_key = INITIAL_CHAIN_KEY;

		chain_head = 1;

	}

	chain_key = iterate_chain_key(chain_key, class_idx);
@@ -4636,7 +4636,7 @@ static void remove_class_from_lock_chain(struct pending_free *pf, 
	return;



recalc:

	chain_key = 0;

	chain_key = INITIAL_CHAIN_KEY;

	for (i = chain->base; i < chain->base + chain->depth; i++)

		chain_key = iterate_chain_key(chain_key, chain_hlocks[i] + 1);

	if (chain->depth && chain->chain_key == chain_key)