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author | Bart Van Assche <bvanassche@acm.org> | 2019-02-14 15:00:46 -0800 |
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committer | Ingo Molnar <mingo@kernel.org> | 2019-02-28 07:55:43 +0100 |
commit | a0b0fd53e1e67639b303b15939b9c653dbe7a8c4 (patch) | |
tree | 2ad0c4039a0bd9ebc15e03cc6f7f3d2325a23900 /include/linux/lockdep.h | |
parent | 29fc33fb7283970701355dc89badba4ed21c7092 (diff) | |
download | linux-a0b0fd53e1e67639b303b15939b9c653dbe7a8c4.tar.gz linux-a0b0fd53e1e67639b303b15939b9c653dbe7a8c4.tar.bz2 linux-a0b0fd53e1e67639b303b15939b9c653dbe7a8c4.zip |
locking/lockdep: Free lock classes that are no longer in use
Instead of leaving lock classes that are no longer in use in the
lock_classes array, reuse entries from that array that are no longer in
use. Maintain a linked list of free lock classes with list head
'free_lock_class'. Only add freed lock classes to the free_lock_classes
list after a grace period to avoid that a lock_classes[] element would
be reused while an RCU reader is accessing it. Since the lockdep
selftests run in a context where sleeping is not allowed and since the
selftests require that lock resetting/zapping works with debug_locks
off, make the behavior of lockdep_free_key_range() and
lockdep_reset_lock() depend on whether or not these are called from
the context of the lockdep selftests.
Thanks to Peter for having shown how to modify get_pending_free()
such that that function does not have to sleep.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-12-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/lockdep.h')
-rw-r--r-- | include/linux/lockdep.h | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 66eee1ba0f2a..619ec3f26cdc 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -63,7 +63,8 @@ extern struct lock_class_key __lockdep_no_validate__; #define LOCKSTAT_POINTS 4 /* - * The lock-class itself: + * The lock-class itself. The order of the structure members matters. + * reinit_class() zeroes the key member and all subsequent members. */ struct lock_class { /* @@ -72,7 +73,9 @@ struct lock_class { struct hlist_node hash_entry; /* - * global list of all lock-classes: + * Entry in all_lock_classes when in use. Entry in free_lock_classes + * when not in use. Instances that are being freed are on one of the + * zapped_classes lists. */ struct list_head lock_entry; @@ -104,7 +107,7 @@ struct lock_class { unsigned long contention_point[LOCKSTAT_POINTS]; unsigned long contending_point[LOCKSTAT_POINTS]; #endif -}; +} __no_randomize_layout; #ifdef CONFIG_LOCK_STAT struct lock_time { |