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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: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Frederic Weisbecker 2018-12-28 06:02:01 +01:00 committed by Ingo Molnar
parent 436a49ae7b
commit bba2a8f1f9
2 changed files with 15 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
kernel/locking/lockdep.c
View File

@ -1624,29 +1624,18 @@ static const char *state_rnames[] = {
static inline const char *state_name(enum lock_usage_bit bit) 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) static int exclusive_bit(int new_bit)
{ {
/* int state = new_bit & LOCK_USAGE_STATE_MASK;
* USED_IN int dir = new_bit & LOCK_USAGE_DIR_MASK;
* 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;
/* /*
* keep state, bit flip the direction and strip read. * 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, 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) enum lock_usage_bit new_bit)
{ {
int excl_bit = exclusive_bit(new_bit); int excl_bit = exclusive_bit(new_bit);
int read = new_bit & 1; int read = new_bit & LOCK_USAGE_READ_MASK;
int dir = new_bit & 2; int dir = new_bit & LOCK_USAGE_DIR_MASK;
/* /*
* mark USED_IN has to look forwards -- to ensure no dependency * 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. * states.
*/ */
if ((!read || !dir || STRICT_READ_CHECKS) && 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; return 0;
/* /*
* Check for read in write conflicts * Check for read in write conflicts
*/ */
if (!read) { 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; return 0;
if (STRICT_READ_CHECKS && if (STRICT_READ_CHECKS &&
!usage(curr, this, excl_bit + 1, !usage(curr, this, excl_bit + LOCK_USAGE_READ_MASK,
state_name(new_bit + 1))) state_name(new_bit + LOCK_USAGE_READ_MASK)))
return 0; return 0;
} }
@ -2723,7 +2712,7 @@ mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit)
hlock = curr->held_locks + i; hlock = curr->held_locks + i;
if (hlock->read) if (hlock->read)
hlock_bit += 1; /* READ */ hlock_bit += LOCK_USAGE_READ_MASK;
BUG_ON(hlock_bit >= LOCK_USAGE_STATES); BUG_ON(hlock_bit >= LOCK_USAGE_STATES);

4
kernel/locking/lockdep_internals.h
View File

@ -22,6 +22,10 @@ enum lock_usage_bit {
LOCK_USAGE_STATES 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: * Usage-state bitmasks:
*/ */