From: Yuyang Du <duyuyang@gmail.com>
To: peterz@infradead.org, will.deacon@arm.com, mingo@kernel.org
Cc: bvanassche@acm.org, ming.lei@redhat.com,
linux-kernel@vger.kernel.org, joe@perches.com,
Yuyang Du <duyuyang@gmail.com>
Subject: [PATCH v3 03/18] locking/lockdep: Adjust lock usage bit character checks
Date: Thu, 21 Mar 2019 15:57:10 +0800 [thread overview]
Message-ID: <20190321075725.14054-4-duyuyang@gmail.com> (raw)
In-Reply-To: <20190321075725.14054-1-duyuyang@gmail.com>
The lock usage bit characters are defined and determined with tricks. Use a
macro and 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>
---
kernel/locking/lockdep.c | 21 ++++++++++++++++-----
kernel/locking/lockdep_internals.h | 1 +
2 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 41137ad..db0473d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -514,15 +514,26 @@ 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 + 2))
+ /*
+ * 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_TO_ENABLED_STEP)) {
c = '+';
- if (class->usage_mask & lock_flag(bit)) {
- c = '-';
- if (class->usage_mask & lock_flag(bit + 2))
+ if (class->usage_mask & lock_flag(bit))
c = '?';
- }
+ } else if (class->usage_mask & lock_flag(bit))
+ c = '-';
return c;
}
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index d4c1974..2fd31d5 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -25,6 +25,7 @@ enum lock_usage_bit {
#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))
+#define LOCK_USAGE_TO_ENABLED_STEP 2
/*
* Usage-state bitmasks:
--
1.8.3.1
next prev parent reply other threads:[~2019-03-21 7:57 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-21 7:57 [PATCH v3 00/18] locking/lockdep: Add comments and make some code Yuyang Du
2019-03-21 7:57 ` [PATCH v3 01/18] locking/lockdep: Change all print_*() return type to void Yuyang Du
2019-03-21 7:57 ` [PATCH v3 02/18] locking/lockdep: Add description and explanation in lockdep design doc Yuyang Du
2019-03-21 7:57 ` Yuyang Du [this message]
2019-03-21 7:57 ` [PATCH v3 04/18] locking/lockdep: Remove useless conditional macro Yuyang Du
2019-03-21 7:57 ` [PATCH v3 05/18] locking/lockdep: Print the right depth for chain key colission Yuyang Du
2019-03-21 7:57 ` [PATCH v3 06/18] locking/lockdep: Update obsolete struct field description Yuyang Du
2019-03-21 7:57 ` [PATCH v3 07/18] locking/lockdep: Use lockdep_init_task for task initiation consistently Yuyang Du
2019-03-21 7:57 ` [PATCH v3 08/18] locking/lockdep: Define INITIAL_CHAIN_KEY for chain keys to start with Yuyang Du
2019-03-21 7:57 ` [PATCH v3 09/18] locking/lockdep: Change the range of class_idx in held_lock struct Yuyang Du
2019-03-21 7:57 ` [PATCH v3 10/18] locking/lockdep: Remove unused argument in validate_chain() and check_deadlock() Yuyang Du
2019-03-21 7:57 ` [PATCH v3 11/18] locking/lockdep: Update comment Yuyang Du
2019-03-21 7:57 ` [PATCH v3 12/18] locking/lockdep: Remove unnecessary function pointer argument Yuyang Du
2019-03-21 7:57 ` [PATCH v3 13/18] locking/lockdep: Change type of the element field in circular_queue Yuyang Du
2019-03-21 7:57 ` [PATCH v3 14/18] locking/lockdep: Change the return type of __cq_dequeue() Yuyang Du
2019-03-21 7:57 ` [PATCH v3 15/18] locking/lockdep: Avoid constant checks in __bfs by using offset reference Yuyang Du
2019-03-21 7:57 ` [PATCH v3 16/18] locking/lockdep: Combine check_noncircular and check_redundant Yuyang Du
2019-03-21 7:57 ` [PATCH v3 17/18] locking/lockdep: Update comments on dependency search Yuyang Du
2019-03-21 7:57 ` [PATCH v3 18/18] locking/lockdep: Add explanation to lock usage rules in lockdep design doc Yuyang Du
2019-04-04 5:03 ` Question on a lockdep test case about mixed read-write ABBA Yuyang Du
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