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, akpm@linux-foundation.org,
willy@infradead.org, npiggin@gmail.com, kernel-team@lge.com
Subject: [PATCH v7 01/16] lockdep: Refactor lookup_chain_cache()
Date: Wed, 24 May 2017 17:59:34 +0900 [thread overview]
Message-ID: <1495616389-29772-2-git-send-email-byungchul.park@lge.com> (raw)
In-Reply-To: <1495616389-29772-1-git-send-email-byungchul.park@lge.com>
Currently, lookup_chain_cache() provides both 'lookup' and 'add'
functionalities in a function. However, each 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 before.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
---
kernel/locking/lockdep.c | 132 ++++++++++++++++++++++++++++++-----------------
1 file changed, 86 insertions(+), 46 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 4d7ffc0..0c6e6b7 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2110,14 +2110,15 @@ static int check_no_collision(struct task_struct *curr,
}
/*
- * 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.)
+ * Adds a dependency chain into chain hashtable. And must be called with
+ * graph_lock held.
+ *
+ * Return 0 if fail, and graph_lock is released.
+ * Return 1 if succeed, with graph_lock 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);
@@ -2125,49 +2126,18 @@ 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;
@@ -2219,6 +2189,75 @@ static inline int lookup_chain_cache(struct task_struct *curr,
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)
{
@@ -2229,11 +2268,11 @@ 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:
*
@@ -2264,9 +2303,10 @@ 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
--
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next prev parent reply other threads:[~2017-05-24 9:00 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-24 8:59 [PATCH v7 00/16] lockdep: Implement crossrelease feature Byungchul Park
2017-05-24 8:59 ` Byungchul Park [this message]
2017-05-24 8:59 ` [PATCH v7 02/16] lockdep: Add a function building a chain between two classes Byungchul Park
2017-05-24 8:59 ` [PATCH v7 03/16] lockdep: Change the meaning of check_prev_add()'s return value Byungchul Park
2017-05-24 8:59 ` [PATCH v7 04/16] lockdep: Make check_prev_add() able to handle external stack_trace Byungchul Park
2017-05-24 8:59 ` [PATCH v7 05/16] lockdep: Implement crossrelease feature Byungchul Park
2017-06-13 0:33 ` Byungchul Park
2017-06-22 23:27 ` Byungchul Park
2017-07-11 16:04 ` Peter Zijlstra
2017-07-12 2:24 ` Byungchul Park
2017-05-24 8:59 ` [PATCH v7 06/16] lockdep: Detect and handle hist_lock ring buffer overwrite Byungchul Park
2017-07-11 16:12 ` Peter Zijlstra
2017-07-12 2:00 ` Byungchul Park
2017-07-12 7:56 ` Peter Zijlstra
2017-07-13 2:07 ` Byungchul Park
2017-07-13 8:14 ` Peter Zijlstra
2017-07-13 8:57 ` Byungchul Park
2017-07-13 9:50 ` Peter Zijlstra
2017-07-13 10:09 ` Byungchul Park
2017-07-13 10:29 ` Peter Zijlstra
2017-07-13 11:12 ` Peter Zijlstra
2017-07-13 11:23 ` Byungchul Park
2017-07-14 1:41 ` Byungchul Park
2017-07-14 6:42 ` Byungchul Park
2017-07-21 13:54 ` Peter Zijlstra
2017-07-25 6:29 ` Byungchul Park
2017-07-25 8:45 ` Peter Zijlstra
2017-07-13 11:19 ` Byungchul Park
2017-07-18 1:25 ` Byungchul Park
2017-05-24 8:59 ` [PATCH v7 07/16] lockdep: Handle non(or multi)-acquisition of a crosslock Byungchul Park
2017-05-24 8:59 ` [PATCH v7 08/16] lockdep: Avoid adding redundant direct links of crosslocks Byungchul Park
2017-07-25 15:41 ` Peter Zijlstra
2017-07-26 7:16 ` Byungchul Park
2017-05-24 8:59 ` [PATCH v7 09/16] lockdep: Fix incorrect condition to print bug msgs for MAX_LOCKDEP_CHAIN_HLOCKS Byungchul Park
2017-05-24 8:59 ` [PATCH v7 10/16] lockdep: Make print_circular_bug() aware of crossrelease Byungchul Park
2017-05-24 8:59 ` [PATCH v7 11/16] lockdep: Apply crossrelease to completions Byungchul Park
2017-05-24 8:59 ` [PATCH v7 12/16] pagemap.h: Remove trailing white space Byungchul Park
2017-05-24 8:59 ` [PATCH v7 13/16] lockdep: Apply crossrelease to PG_locked locks Byungchul Park
2017-05-24 8:59 ` [PATCH v7 14/16] lockdep: Apply lock_acquire(release) on __Set(__Clear)PageLocked Byungchul Park
2017-05-24 8:59 ` [PATCH v7 15/16] lockdep: Move data of CONFIG_LOCKDEP_PAGELOCK from page to page_ext Byungchul Park
2017-05-24 8:59 ` [PATCH v7 16/16] lockdep: Crossrelease feature documentation Byungchul Park
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