From: Byungchul Park <byungchul.park@lge.com>
To: peterz@infradead.org, mingo@kernel.org
Cc: tglx@linutronix.de, walken@google.com, boqun.feng@gmail.com,
kirill@shutemov.name, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, iamjoonsoo.kim@lge.com,
akpm@linux-foundation.org, npiggin@gmail.com
Subject: [PATCH v3 03/15] lockdep: Refactor lookup_chain_cache()
Date: Tue, 13 Sep 2016 18:45:02 +0900 [thread overview]
Message-ID: <1473759914-17003-4-git-send-email-byungchul.park@lge.com> (raw)
In-Reply-To: <1473759914-17003-1-git-send-email-byungchul.park@lge.com>
Currently, lookup_chain_cache() provides both 'lookup' and 'add'
functionalities in a function. However, each one is useful. So this
patch makes lookup_chain_cache() only do lookup functionality and
makes add_chain_cahce() only do add functionality. And it's more
readable than these functionalities are mixed in a function.
Crossrelease feature also needs to use each one separately.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
---
kernel/locking/lockdep.c | 129 +++++++++++++++++++++++++++++------------------
1 file changed, 81 insertions(+), 48 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 81f1a71..5df56aa 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2105,15 +2105,9 @@ static int check_no_collision(struct task_struct *curr,
return 1;
}
-/*
- * Look up a dependency chain. If the key is not present yet then
- * add it and return 1 - in this case the new dependency chain is
- * validated. If the key is already hashed, return 0.
- * (On return with 1 graph_lock is held.)
- */
-static inline int lookup_chain_cache(struct task_struct *curr,
- struct held_lock *hlock,
- u64 chain_key)
+static inline int add_chain_cache(struct task_struct *curr,
+ struct held_lock *hlock,
+ u64 chain_key)
{
struct lock_class *class = hlock_class(hlock);
struct hlist_head *hash_head = chainhashentry(chain_key);
@@ -2121,49 +2115,18 @@ static inline int lookup_chain_cache(struct task_struct *curr,
int i, j;
/*
+ * Allocate a new chain entry from the static array, and add
+ * it to the hash:
+ */
+
+ /*
* We might need to take the graph lock, ensure we've got IRQs
* disabled to make this an IRQ-safe lock.. for recursion reasons
* lockdep won't complain about its own locking errors.
*/
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return 0;
- /*
- * We can walk it lock-free, because entries only get added
- * to the hash:
- */
- hlist_for_each_entry_rcu(chain, hash_head, entry) {
- if (chain->chain_key == chain_key) {
-cache_hit:
- debug_atomic_inc(chain_lookup_hits);
- if (!check_no_collision(curr, hlock, chain))
- return 0;
- if (very_verbose(class))
- printk("\nhash chain already cached, key: "
- "%016Lx tail class: [%p] %s\n",
- (unsigned long long)chain_key,
- class->key, class->name);
- return 0;
- }
- }
- if (very_verbose(class))
- printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
- (unsigned long long)chain_key, class->key, class->name);
- /*
- * Allocate a new chain entry from the static array, and add
- * it to the hash:
- */
- if (!graph_lock())
- return 0;
- /*
- * We have to walk the chain again locked - to avoid duplicates:
- */
- hlist_for_each_entry(chain, hash_head, entry) {
- if (chain->chain_key == chain_key) {
- graph_unlock();
- goto cache_hit;
- }
- }
if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
if (!debug_locks_off_graph_unlock())
return 0;
@@ -2215,6 +2178,75 @@ cache_hit:
return 1;
}
+/*
+ * Look up a dependency chain.
+ */
+static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
+{
+ struct hlist_head *hash_head = chainhashentry(chain_key);
+ struct lock_chain *chain;
+
+ /*
+ * We can walk it lock-free, because entries only get added
+ * to the hash:
+ */
+ hlist_for_each_entry_rcu(chain, hash_head, entry) {
+ if (chain->chain_key == chain_key) {
+ debug_atomic_inc(chain_lookup_hits);
+ return chain;
+ }
+ }
+ return NULL;
+}
+
+/*
+ * If the key is not present yet in dependency chain cache then
+ * add it and return 1 - in this case the new dependency chain is
+ * validated. If the key is already hashed, return 0.
+ * (On return with 1 graph_lock is held.)
+ */
+static inline int lookup_chain_cache_add(struct task_struct *curr,
+ struct held_lock *hlock,
+ u64 chain_key)
+{
+ struct lock_class *class = hlock_class(hlock);
+ struct lock_chain *chain = lookup_chain_cache(chain_key);
+
+ if (chain) {
+cache_hit:
+ if (!check_no_collision(curr, hlock, chain))
+ return 0;
+
+ if (very_verbose(class))
+ printk("\nhash chain already cached, key: "
+ "%016Lx tail class: [%p] %s\n",
+ (unsigned long long)chain_key,
+ class->key, class->name);
+ return 0;
+ }
+
+ if (very_verbose(class))
+ printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
+ (unsigned long long)chain_key, class->key, class->name);
+
+ if (!graph_lock())
+ return 0;
+
+ /*
+ * We have to walk the chain again locked - to avoid duplicates:
+ */
+ chain = lookup_chain_cache(chain_key);
+ if (chain) {
+ graph_unlock();
+ goto cache_hit;
+ }
+
+ if (!add_chain_cache(curr, hlock, chain_key))
+ return 0;
+
+ return 1;
+}
+
static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
struct held_lock *hlock, int chain_head, u64 chain_key)
{
@@ -2225,11 +2257,11 @@ static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
*
* We look up the chain_key and do the O(N^2) check and update of
* the dependencies only if this is a new dependency chain.
- * (If lookup_chain_cache() returns with 1 it acquires
+ * (If lookup_chain_cache_add() return with 1 it acquires
* graph_lock for us)
*/
if (!hlock->trylock && hlock->check &&
- lookup_chain_cache(curr, hlock, chain_key)) {
+ lookup_chain_cache_add(curr, hlock, chain_key)) {
/*
* Check whether last held lock:
*
@@ -2260,9 +2292,10 @@ static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
if (!chain_head && ret != 2)
if (!check_prevs_add(curr, hlock))
return 0;
+
graph_unlock();
} else
- /* after lookup_chain_cache(): */
+ /* after lookup_chain_cache_add(): */
if (unlikely(!debug_locks))
return 0;
--
1.9.1
next prev parent reply other threads:[~2016-09-13 9:50 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-13 9:44 [PATCH v3 00/15] lockdep: Implement crossrelease feature Byungchul Park
2016-09-13 9:45 ` [PATCH v3 01/15] x86/dumpstack: Optimize save_stack_trace Byungchul Park
2016-09-13 13:18 ` Josh Poimboeuf
2016-09-13 14:54 ` Byungchul Park
2016-09-13 9:45 ` [PATCH v3 02/15] x86/dumpstack: Add save_stack_trace()_fast() Byungchul Park
2016-09-13 13:20 ` Josh Poimboeuf
2016-09-13 9:45 ` Byungchul Park [this message]
2016-09-15 15:33 ` [PATCH v3 03/15] lockdep: Refactor lookup_chain_cache() Nilay Vaish
2016-09-19 3:05 ` Byungchul Park
2016-09-19 16:36 ` Nilay Vaish
2016-09-20 2:00 ` Byungchul Park
2016-09-13 9:45 ` [PATCH v3 04/15] lockdep: Add a function building a chain between two classes Byungchul Park
2016-09-13 9:45 ` [PATCH v3 05/15] lockdep: Make check_prev_add can use a separate stack_trace Byungchul Park
2016-09-13 9:45 ` [PATCH v3 06/15] lockdep: Make save_trace can skip stack tracing of the current Byungchul Park
2016-09-13 9:45 ` [PATCH v3 07/15] lockdep: Implement crossrelease feature Byungchul Park
2016-09-13 10:05 ` Peter Zijlstra
2016-09-13 12:09 ` Peter Zijlstra
2016-09-13 15:14 ` Byungchul Park
2016-09-13 15:05 ` Peter Zijlstra
2016-09-13 17:12 ` Byungchul Park
2016-09-13 19:38 ` Peter Zijlstra
2016-09-13 21:42 ` Peter Zijlstra
2016-09-14 1:01 ` Byungchul Park
2016-09-14 2:27 ` Byungchul Park
2016-09-14 4:49 ` Byungchul Park
2016-09-14 8:11 ` Peter Zijlstra
2016-09-19 2:41 ` Byungchul Park
2016-09-19 8:50 ` Peter Zijlstra
2016-09-20 5:50 ` Byungchul Park
2016-09-20 6:26 ` Byungchul Park
2016-09-21 1:37 ` Byungchul Park
2016-09-22 2:57 ` Byungchul Park
2016-09-13 9:45 ` [PATCH v3 08/15] lockdep: Make crossrelease use save_stack_trace_fast() Byungchul Park
2016-09-13 9:45 ` [PATCH v3 09/15] lockdep: Make print_circular_bug() crosslock-aware Byungchul Park
2016-09-13 9:45 ` [PATCH v3 10/15] lockdep: Apply crossrelease to completion operation Byungchul Park
2016-09-13 9:45 ` [PATCH v3 11/15] pagemap.h: Remove trailing white space Byungchul Park
2016-09-13 9:45 ` [PATCH v3 12/15] lockdep: Apply crossrelease to PG_locked lock Byungchul Park
2016-09-13 9:45 ` [PATCH v3 13/15] lockdep: Apply lock_acquire(release) on __Set(__Clear)PageLocked Byungchul Park
2016-09-13 9:45 ` [PATCH v3 14/15] lockdep: Move data used in CONFIG_LOCKDEP_PAGELOCK from page to page_ext Byungchul Park
2016-09-13 9:45 ` [PATCH v3 15/15] lockdep: Crossrelease feature documentation Byungchul Park
2016-09-15 17:25 ` Nilay Vaish
2016-09-19 2:59 ` Byungchul Park
2016-09-16 15:47 ` Nilay Vaish
2016-09-19 3:00 ` Byungchul Park
2016-09-20 5:00 ` Byungchul Park
2016-09-13 9:58 ` [FYI] Output of 'cat /proc/lockdep' after applying crossrelease Byungchul Park
2016-11-02 5:42 ` [REVISED DOC on v3] Crossrelease Lockdep Byungchul Park
2016-11-03 8:18 ` Byungchul Park
2016-11-08 2:54 ` Byungchul Park
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