linux-kernel - [PATCH v2 1/5] locking/lockdep: Remove add_chain_cache

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Date:   Tue,  2 Oct 2018 16:19:16 -0400
From:   Waiman Long <longman@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Will Deacon <will.deacon@....com>
Cc:     linux-kernel@...r.kernel.org, Waiman Long <longman@...hat.com>
Subject: [PATCH v2 1/5] locking/lockdep: Remove add_chain_cache_classes()

The inline function add_chain_cache_classes() is defined, but has no
caller. Just remove it.

Signed-off-by: Waiman Long <longman@...hat.com>
---
 kernel/locking/lockdep.c | 70 ----------------------------------------
 1 file changed, 70 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index dd13f865ad40..8f9de7cd11ab 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2147,76 +2147,6 @@ static int check_no_collision(struct task_struct *curr,
 	return 1;
 }
 
-/*
- * This is for building a chain between just two different classes,
- * instead of adding a new hlock upon current, which is done by
- * add_chain_cache().
- *
- * This can be called in any context with two classes, while
- * add_chain_cache() must be done within the lock owener's context
- * since it uses hlock which might be racy in another context.
- */
-static inline int add_chain_cache_classes(unsigned int prev,
-					  unsigned int next,
-					  unsigned int irq_context,
-					  u64 chain_key)
-{
-	struct hlist_head *hash_head = chainhashentry(chain_key);
-	struct lock_chain *chain;
-
-	/*
-	 * 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;
-
-	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
-		if (!debug_locks_off_graph_unlock())
-			return 0;
-
-		print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
-		dump_stack();
-		return 0;
-	}
-
-	chain = lock_chains + nr_lock_chains++;
-	chain->chain_key = chain_key;
-	chain->irq_context = irq_context;
-	chain->depth = 2;
-	if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
-		chain->base = nr_chain_hlocks;
-		nr_chain_hlocks += chain->depth;
-		chain_hlocks[chain->base] = prev - 1;
-		chain_hlocks[chain->base + 1] = next -1;
-	}
-#ifdef CONFIG_DEBUG_LOCKDEP
-	/*
-	 * Important for check_no_collision().
-	 */
-	else {
-		if (!debug_locks_off_graph_unlock())
-			return 0;
-
-		print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
-		dump_stack();
-		return 0;
-	}
-#endif
-
-	hlist_add_head_rcu(&chain->entry, hash_head);
-	debug_atomic_inc(chain_lookup_misses);
-	inc_chains();
-
-	return 1;
-}
-
 /*
  * Adds a dependency chain into chain hashtable. And must be called with
  * graph_lock held.
-- 
2.18.0