mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-27 13:05:10 +07:00
726328d92a
This patch updates/fixes all spin_unlock_wait() implementations. The update is in semantics; where it previously was only a control dependency, we now upgrade to a full load-acquire to match the store-release from the spin_unlock() we waited on. This ensures that when spin_unlock_wait() returns, we're guaranteed to observe the full critical section we waited on. This fixes a number of spin_unlock_wait() users that (not unreasonably) rely on this. I also fixed a number of ticket lock versions to only wait on the current lock holder, instead of for a full unlock, as this is sufficient. Furthermore; again for ticket locks; I added an smp_rmb() in between the initial ticket load and the spin loop testing the current value because I could not convince myself the address dependency is sufficient, esp. if the loads are of different sizes. I'm more than happy to remove this smp_rmb() again if people are certain the address dependency does indeed work as expected. Note: PPC32 will be fixed independently 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> Cc: chris@zankel.net Cc: cmetcalf@mellanox.com Cc: davem@davemloft.net Cc: dhowells@redhat.com Cc: james.hogan@imgtec.com Cc: jejb@parisc-linux.org Cc: linux@armlinux.org.uk Cc: mpe@ellerman.id.au Cc: ralf@linux-mips.org Cc: realmz6@gmail.com Cc: rkuo@codeaurora.org Cc: rth@twiddle.net Cc: schwidefsky@de.ibm.com Cc: tony.luck@intel.com Cc: vgupta@synopsys.com Cc: ysato@users.sourceforge.jp Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
90 lines
2.6 KiB
C
90 lines
2.6 KiB
C
#ifndef __LINUX_SPINLOCK_UP_H
|
|
#define __LINUX_SPINLOCK_UP_H
|
|
|
|
#ifndef __LINUX_SPINLOCK_H
|
|
# error "please don't include this file directly"
|
|
#endif
|
|
|
|
#include <asm/processor.h> /* for cpu_relax() */
|
|
#include <asm/barrier.h>
|
|
|
|
/*
|
|
* include/linux/spinlock_up.h - UP-debug version of spinlocks.
|
|
*
|
|
* portions Copyright 2005, Red Hat, Inc., Ingo Molnar
|
|
* Released under the General Public License (GPL).
|
|
*
|
|
* In the debug case, 1 means unlocked, 0 means locked. (the values
|
|
* are inverted, to catch initialization bugs)
|
|
*
|
|
* No atomicity anywhere, we are on UP. However, we still need
|
|
* the compiler barriers, because we do not want the compiler to
|
|
* move potentially faulting instructions (notably user accesses)
|
|
* into the locked sequence, resulting in non-atomic execution.
|
|
*/
|
|
|
|
#ifdef CONFIG_DEBUG_SPINLOCK
|
|
#define arch_spin_is_locked(x) ((x)->slock == 0)
|
|
|
|
static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
|
|
{
|
|
smp_cond_load_acquire(&lock->slock, VAL);
|
|
}
|
|
|
|
static inline void arch_spin_lock(arch_spinlock_t *lock)
|
|
{
|
|
lock->slock = 0;
|
|
barrier();
|
|
}
|
|
|
|
static inline void
|
|
arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
|
|
{
|
|
local_irq_save(flags);
|
|
lock->slock = 0;
|
|
barrier();
|
|
}
|
|
|
|
static inline int arch_spin_trylock(arch_spinlock_t *lock)
|
|
{
|
|
char oldval = lock->slock;
|
|
|
|
lock->slock = 0;
|
|
barrier();
|
|
|
|
return oldval > 0;
|
|
}
|
|
|
|
static inline void arch_spin_unlock(arch_spinlock_t *lock)
|
|
{
|
|
barrier();
|
|
lock->slock = 1;
|
|
}
|
|
|
|
/*
|
|
* Read-write spinlocks. No debug version.
|
|
*/
|
|
#define arch_read_lock(lock) do { barrier(); (void)(lock); } while (0)
|
|
#define arch_write_lock(lock) do { barrier(); (void)(lock); } while (0)
|
|
#define arch_read_trylock(lock) ({ barrier(); (void)(lock); 1; })
|
|
#define arch_write_trylock(lock) ({ barrier(); (void)(lock); 1; })
|
|
#define arch_read_unlock(lock) do { barrier(); (void)(lock); } while (0)
|
|
#define arch_write_unlock(lock) do { barrier(); (void)(lock); } while (0)
|
|
|
|
#else /* DEBUG_SPINLOCK */
|
|
#define arch_spin_is_locked(lock) ((void)(lock), 0)
|
|
#define arch_spin_unlock_wait(lock) do { barrier(); (void)(lock); } while (0)
|
|
/* for sched/core.c and kernel_lock.c: */
|
|
# define arch_spin_lock(lock) do { barrier(); (void)(lock); } while (0)
|
|
# define arch_spin_lock_flags(lock, flags) do { barrier(); (void)(lock); } while (0)
|
|
# define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0)
|
|
# define arch_spin_trylock(lock) ({ barrier(); (void)(lock); 1; })
|
|
#endif /* DEBUG_SPINLOCK */
|
|
|
|
#define arch_spin_is_contended(lock) (((void)(lock), 0))
|
|
|
|
#define arch_read_can_lock(lock) (((void)(lock), 1))
|
|
#define arch_write_can_lock(lock) (((void)(lock), 1))
|
|
|
|
#endif /* __LINUX_SPINLOCK_UP_H */
|