diff options
| author | Yuyang Du | 2019-05-06 16:19:19 +0800 |
|---|---|---|
| committer | Ingo Molnar | 2019-06-03 11:55:35 +0200 |
| commit | c52478f4f38ace598475413a08dba9b9fd827eaf (patch) | |
| tree | 7218b89f958ba7d764a6de1f3b81b43bfa6d75bd /kernel/locking | |
| parent | c01fbbc83f42748b3ed094497933601e6c9e0a03 (diff) | |
locking/lockdep: Adjust lock usage bit character checks
The lock usage bit characters are defined and determined with tricks.
Add some explanation to make it a bit clearer, then adjust the logic to
check the usage, which optimizes the code a bit.
No functional change.
Signed-off-by: Yuyang Du <duyuyang@gmail.com>
Signed-off-by: Peter 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/20190506081939.74287-4-duyuyang@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking')
| -rw-r--r-- | kernel/locking/lockdep.c | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 109b56267c8f..a033df00fd1d 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -500,15 +500,26 @@ static inline unsigned long lock_flag(enum lock_usage_bit bit) static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) { + /* + * The usage character defaults to '.' (i.e., irqs disabled and not in + * irq context), which is the safest usage category. + */ char c = '.'; - if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) + /* + * The order of the following usage checks matters, which will + * result in the outcome character as follows: + * + * - '+': irq is enabled and not in irq context + * - '-': in irq context and irq is disabled + * - '?': in irq context and irq is enabled + */ + if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) { c = '+'; - if (class->usage_mask & lock_flag(bit)) { - c = '-'; - if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) + if (class->usage_mask & lock_flag(bit)) c = '?'; - } + } else if (class->usage_mask & lock_flag(bit)) + c = '-'; return c; } |