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locking/lockdep: Add a function building a chain between two classes

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Crossrelease needs to build a chain between two classes regardless of
their contexts. However, add_chain_cache() cannot be used for that
purpose since it assumes that it's called in the acquisition context
of the hlock. So this patch introduces a new function doing it.

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Cc: willy@infradead.org
Link: http://lkml.kernel.org/r/1502089981-21272-3-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Byungchul Park 2017-08-07 16:12:49 +09:00 committed by Ingo Molnar
parent 545c23f2e9
commit 49347a986a
1 changed files with 70 additions and 0 deletions
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70
kernel/locking/lockdep.c
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@ -2150,6 +2150,76 @@ 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.