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authorPeter Zijlstra <peterz@infradead.org>2016-05-30 18:31:33 +0200
committerIngo Molnar <mingo@kernel.org>2016-06-08 14:22:00 +0200
commitdfaaf3fa01d65cf6e2072965bb0b7aaa7285344f (patch)
treee2b993df8b9fd932668875f3f985beadecd12f9e /kernel/locking
parented8ebd1d514126c0e54fbdbd231427dc91c877c2 (diff)
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op-kernel-dev-dfaaf3fa01d65cf6e2072965bb0b7aaa7285344f.tar.gz
locking/lockdep: Use __jhash_mix() for iterate_chain_key()
Use __jhash_mix() to mix the class_idx into the class_key. This function provides better mixing than the previously used, home grown mix function. Leave hashing to the professionals :-) Suggested-by: George Spelvin <linux@sciencehorizons.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> 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: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking')
-rw-r--r--kernel/locking/lockdep.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 81f1a71..589d763 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -46,6 +46,7 @@
#include <linux/gfp.h>
#include <linux/kmemcheck.h>
#include <linux/random.h>
+#include <linux/jhash.h>
#include <asm/sections.h>
@@ -309,10 +310,14 @@ static struct hlist_head chainhash_table[CHAINHASH_SIZE];
* It's a 64-bit hash, because it's important for the keys to be
* unique.
*/
-#define iterate_chain_key(key1, key2) \
- (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
- ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
- (key2))
+static inline u64 iterate_chain_key(u64 key, u32 idx)
+{
+ u32 k0 = key, k1 = key >> 32;
+
+ __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
+
+ return k0 | (u64)k1 << 32;
+}
void lockdep_off(void)
{
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