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lockdep: Fix lock_chain::base size

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lock_chain::base is used to store an index into the chain_hlocks[]
array, however that array contains more elements than can be indexed
using the u16.

Change the lock_chain structure to use a bitfield to encode the data
it needs and add BUILD_BUG_ON() assertions to check the fields are
wide enough.

Also, for DEBUG_LOCKDEP, assert that we don't run out of elements of
that array; as that would wreck the collision detectoring.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alfredo Alvarez Fernandez <alfredoalvarezfernandez@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160330093659.GS3408@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-03-30 11:36:59 +02:00 • committed by Ingo Molnar
parent c246975662
commit 75dd602a51
3 changed files with 30 additions and 4 deletions
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8
include/linux/lockdep.h
View file

@ -196,9 +196,11 @@ struct lock_list {
* We record lock dependency chains, so that we can cache them:
*/
struct lock_chain {
u8 irq_context;
u8 depth;
u16 base;
/* see BUILD_BUG_ON()s in lookup_chain_cache() */
unsigned int irq_context : 2,
depth : 6,
base : 24;
/* 4 byte hole */
struct hlist_node entry;
u64 chain_key;
};