Oops. Sorry, the patch is not tested well! will update it later. On Mon, 2012-03-05 at 11:20 +0800, Alex Shi wrote: > Modern x86 CPU won't hold whole memory bus when executing 'lock' > prefixed instructions unless the instruction destination is crossing 2 > cache lines. If so, it is disaster of system performance. > > Actually if the lock is not in the 'packed' structure, gcc places it > safely under x86 arch. But seems add this checking in > CONFIG_DEBUG_LOCK_ALLOC is harmless. > > btw, change SPIN_BUG_ON macro a little for style complain. > > Inspired-by: Andi Kleen <andi.kleen@xxxxxxxxx> > Signed-off-by: Alex Shi <alex.shi@xxxxxxxxx> > --- > diff --git a/arch/x86/include/asm/cache.h b/arch/x86/include/asm/cache.h > index 48f99f1..79d146e 100644 > --- a/arch/x86/include/asm/cache.h > +++ b/arch/x86/include/asm/cache.h > @@ -7,6 +7,8 @@ > #define L1_CACHE_SHIFT (CONFIG_X86_L1_CACHE_SHIFT) > #define L1_CACHE_BYTES (1 << L1_CACHE_SHIFT) > > +#define L1_CACHE_SIZE_MASK (~(L1_CACHE_BYTES - 1)UL) > + > #define __read_mostly __attribute__((__section__(".data..read_mostly"))) > > #define INTERNODE_CACHE_SHIFT CONFIG_X86_INTERNODE_CACHE_SHIFT > diff --git a/include/asm-generic/cache.h b/include/asm-generic/cache.h > index 1bfcfe5..244e528 100644 > --- a/include/asm-generic/cache.h > +++ b/include/asm-generic/cache.h > @@ -9,4 +9,6 @@ > #define L1_CACHE_SHIFT 5 > #define L1_CACHE_BYTES (1 << L1_CACHE_SHIFT) > > +#define L1_CACHE_SIZE_MASK (~(L1_CACHE_BYTES - 1)UL) > + > #endif /* __ASM_GENERIC_CACHE_H */ > diff --git a/lib/spinlock_debug.c b/lib/spinlock_debug.c > index 5f3eacd..554dcda 100644 > --- a/lib/spinlock_debug.c > +++ b/lib/spinlock_debug.c > @@ -13,6 +13,12 @@ > #include <linux/delay.h> > #include <linux/module.h> > > +#define SPIN_BUG_ON(cond, lock, msg) {if (unlikely(cond)) spin_bug(lock, msg); } > + > +#define is_cross_lines(p) \ > + (((unsigned long)(p) & L1_CACHE_SIZE_MASK) != \ > + (((unsigned long)(p) + sizeof(*p) - 1) & L1_CACHE_SIZE_MASK)) \ > + > void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name, > struct lock_class_key *key) > { > @@ -22,6 +28,8 @@ void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name, > */ > debug_check_no_locks_freed((void *)lock, sizeof(*lock)); > lockdep_init_map(&lock->dep_map, name, key, 0); > + SPIN_BUG_ON(is_cross_lines(lock->raw_lock), lock, > + "!!! the lock cross cache lines !!!"); > #endif > lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; > lock->magic = SPINLOCK_MAGIC; > @@ -40,6 +48,8 @@ void __rwlock_init(rwlock_t *lock, const char *name, > */ > debug_check_no_locks_freed((void *)lock, sizeof(*lock)); > lockdep_init_map(&lock->dep_map, name, key, 0); > + SPIN_BUG_ON(is_cross_lines(lock->raw_lock), lock, > + "!!! the lock cross cache lines !!!"); > #endif > lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED; > lock->magic = RWLOCK_MAGIC; > @@ -75,8 +85,6 @@ static void spin_bug(raw_spinlock_t *lock, const char *msg) > spin_dump(lock, msg); > } > > -#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg) > - > static inline void > debug_spin_lock_before(raw_spinlock_t *lock) > { > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/