Commit bba2a8f1 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
Browse files

locking/lockdep: Provide enum lock_usage_bit mask names 



It makes the code more self-explanatory and tells throughout the code
what magic number refers to:

 - state (Hardirq/Softirq)
 - direction (used in or enabled above state)
 - read or write

We can even remove some comments that were compensating for the lack of
those constant names.

Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/1545973321-24422-3-git-send-email-frederic@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 436a49ae

kernel/locking/lockdep.c

+11 −22
Original line number Diff line number Diff line
@@ -1624,29 +1624,18 @@ static const char *state_rnames[] = { 


static inline const char *state_name(enum lock_usage_bit bit)

{

	return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];

	return (bit & LOCK_USAGE_READ_MASK) ? state_rnames[bit >> 2] : state_names[bit >> 2];

}



static int exclusive_bit(int new_bit)

{

	/*

	 * USED_IN

	 * USED_IN_READ

	 * ENABLED

	 * ENABLED_READ

	 *

	 * bit 0 - write/read

	 * bit 1 - used_in/enabled

	 * bit 2+  state

	 */



	int state = new_bit & ~3;

	int dir = new_bit & 2;

	int state = new_bit & LOCK_USAGE_STATE_MASK;

	int dir = new_bit & LOCK_USAGE_DIR_MASK;



	/*

	 * keep state, bit flip the direction and strip read.

	 */

	return state | (dir ^ 2);

	return state | (dir ^ LOCK_USAGE_DIR_MASK);

}



static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
@@ -2662,8 +2651,8 @@ mark_lock_irq(struct task_struct *curr, struct held_lock *this, 
		enum lock_usage_bit new_bit)

{

	int excl_bit = exclusive_bit(new_bit);

	int read = new_bit & 1;

	int dir = new_bit & 2;

	int read = new_bit & LOCK_USAGE_READ_MASK;

	int dir = new_bit & LOCK_USAGE_DIR_MASK;



	/*

	 * mark USED_IN has to look forwards -- to ensure no dependency
@@ -2687,19 +2676,19 @@ mark_lock_irq(struct task_struct *curr, struct held_lock *this, 
	 * states.

	 */

	if ((!read || !dir || STRICT_READ_CHECKS) &&

			!usage(curr, this, excl_bit, state_name(new_bit & ~1)))

			!usage(curr, this, excl_bit, state_name(new_bit & ~LOCK_USAGE_READ_MASK)))

		return 0;



	/*

	 * Check for read in write conflicts

	 */

	if (!read) {

		if (!valid_state(curr, this, new_bit, excl_bit + 1))

		if (!valid_state(curr, this, new_bit, excl_bit + LOCK_USAGE_READ_MASK))

			return 0;



		if (STRICT_READ_CHECKS &&

			!usage(curr, this, excl_bit + 1,

				state_name(new_bit + 1)))

			!usage(curr, this, excl_bit + LOCK_USAGE_READ_MASK,

				state_name(new_bit + LOCK_USAGE_READ_MASK)))

			return 0;

	}
@@ -2723,7 +2712,7 @@ mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit) 
		hlock = curr->held_locks + i;



		if (hlock->read)

			hlock_bit += 1; /* READ */

			hlock_bit += LOCK_USAGE_READ_MASK;



		BUG_ON(hlock_bit >= LOCK_USAGE_STATES);

kernel/locking/lockdep_internals.h

+4 −0
Original line number Diff line number Diff line
@@ -22,6 +22,10 @@ enum lock_usage_bit { 
	LOCK_USAGE_STATES

};



#define LOCK_USAGE_READ_MASK 1

#define LOCK_USAGE_DIR_MASK  2

#define LOCK_USAGE_STATE_MASK (~(LOCK_USAGE_READ_MASK | LOCK_USAGE_DIR_MASK))



/*

 * Usage-state bitmasks:

 */