Commit-ID: c52478f4f38ace598475413a08dba9b9fd827eaf Gitweb: https://git.kernel.org/tip/c52478f4f38ace598475413a08dba9b9fd827eaf Author: Yuyang Du <duyuy...@gmail.com> AuthorDate: Mon, 6 May 2019 16:19:19 +0800 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Mon, 3 Jun 2019 11:55:35 +0200
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 <duyuy...@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: bvanass...@acm.org Cc: frede...@kernel.org Cc: ming....@redhat.com Cc: will.dea...@arm.com Link: https://lkml.kernel.org/r/20190506081939.74287-4-duyuy...@gmail.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/locking/lockdep.c | 21 ++++++++++++++++----- 1 file 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; }
