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Message-ID: <tip-64f29d1bc9fb8196df3d0f1df694245230e208c0@git.kernel.org>
Date: Thu, 18 Jan 2018 03:00:52 -0800
From: tip-bot for Matthew Wilcox <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: peterz@...radead.org, davem@...emloft.net, hpa@...or.com,
tglx@...utronix.de, mawilcox@...rosoft.com, mingo@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip:locking/core] lockdep: Assign lock keys on registration
Commit-ID: 64f29d1bc9fb8196df3d0f1df694245230e208c0
Gitweb: https://git.kernel.org/tip/64f29d1bc9fb8196df3d0f1df694245230e208c0
Author: Matthew Wilcox <mawilcox@...rosoft.com>
AuthorDate: Wed, 17 Jan 2018 07:14:12 -0800
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 18 Jan 2018 11:56:48 +0100
lockdep: Assign lock keys on registration
Lockdep is assigning lock keys when a lock was looked up. This is
unnecessary; if the lock has never been registered then it is known that it
is not locked. It also complicates the calling convention. Switch to
assigning the lock key in register_lock_class().
Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: "David S. Miller" <davem@...emloft.net>
Link: https://lkml.kernel.org/r/20180117151414.23686-2-willy@infradead.org
---
kernel/locking/lockdep.c | 76 +++++++++++++++++++++++++-----------------------
1 file changed, 40 insertions(+), 36 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 5fa1324..472547d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -647,18 +647,12 @@ static int count_matching_names(struct lock_class *new_class)
return count + 1;
}
-/*
- * Register a lock's class in the hash-table, if the class is not present
- * yet. Otherwise we look it up. We cache the result in the lock object
- * itself, so actual lookup of the hash should be once per lock object.
- */
static inline struct lock_class *
look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
{
struct lockdep_subclass_key *key;
struct hlist_head *hash_head;
struct lock_class *class;
- bool is_static = false;
if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
debug_locks_off();
@@ -671,24 +665,11 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
}
/*
- * Static locks do not have their class-keys yet - for them the key
- * is the lock object itself. If the lock is in the per cpu area,
- * the canonical address of the lock (per cpu offset removed) is
- * used.
+ * If it is not initialised then it has never been locked,
+ * so it won't be present in the hash table.
*/
- if (unlikely(!lock->key)) {
- unsigned long can_addr, addr = (unsigned long)lock;
-
- if (__is_kernel_percpu_address(addr, &can_addr))
- lock->key = (void *)can_addr;
- else if (__is_module_percpu_address(addr, &can_addr))
- lock->key = (void *)can_addr;
- else if (static_obj(lock))
- lock->key = (void *)lock;
- else
- return ERR_PTR(-EINVAL);
- is_static = true;
- }
+ if (unlikely(!lock->key))
+ return NULL;
/*
* NOTE: the class-key must be unique. For dynamic locks, a static
@@ -720,7 +701,35 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
}
}
- return is_static || static_obj(lock->key) ? NULL : ERR_PTR(-EINVAL);
+ return NULL;
+}
+
+/*
+ * Static locks do not have their class-keys yet - for them the key is
+ * the lock object itself. If the lock is in the per cpu area, the
+ * canonical address of the lock (per cpu offset removed) is used.
+ */
+static bool assign_lock_key(struct lockdep_map *lock)
+{
+ unsigned long can_addr, addr = (unsigned long)lock;
+
+ if (__is_kernel_percpu_address(addr, &can_addr))
+ lock->key = (void *)can_addr;
+ else if (__is_module_percpu_address(addr, &can_addr))
+ lock->key = (void *)can_addr;
+ else if (static_obj(lock))
+ lock->key = (void *)lock;
+ else {
+ /* Debug-check: all keys must be persistent! */
+ debug_locks_off();
+ pr_err("INFO: trying to register non-static key.\n");
+ pr_err("the code is fine but needs lockdep annotation.\n");
+ pr_err("turning off the locking correctness validator.\n");
+ dump_stack();
+ return false;
+ }
+
+ return true;
}
/*
@@ -738,18 +747,13 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
DEBUG_LOCKS_WARN_ON(!irqs_disabled());
class = look_up_lock_class(lock, subclass);
- if (likely(!IS_ERR_OR_NULL(class)))
+ if (likely(class))
goto out_set_class_cache;
- /*
- * Debug-check: all keys must be persistent!
- */
- if (IS_ERR(class)) {
- debug_locks_off();
- printk("INFO: trying to register non-static key.\n");
- printk("the code is fine but needs lockdep annotation.\n");
- printk("turning off the locking correctness validator.\n");
- dump_stack();
+ if (!lock->key) {
+ if (!assign_lock_key(lock))
+ return NULL;
+ } else if (!static_obj(lock->key)) {
return NULL;
}
@@ -3498,7 +3502,7 @@ static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
* Clearly if the lock hasn't been acquired _ever_, we're not
* holding it either, so report failure.
*/
- if (IS_ERR_OR_NULL(class))
+ if (!class)
return 0;
/*
@@ -4294,7 +4298,7 @@ void lockdep_reset_lock(struct lockdep_map *lock)
* If the class exists we look it up and zap it:
*/
class = look_up_lock_class(lock, j);
- if (!IS_ERR_OR_NULL(class))
+ if (class)
zap_class(class);
}
/*
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