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Commit 2da2ca24 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull locking fixes from Thomas Gleixner:
 "A set of fixes and updates for the locking code:

   - Prevent lockdep from updating irq state within its own code and
     thereby confusing itself.

   - Buid fix for older GCCs which mistreat anonymous unions

   - Add a missing lockdep annotation in down_read_non_onwer() which
     causes up_read_non_owner() to emit a lockdep splat

   - Remove the custom alpha dec_and_lock() implementation which is
     incorrect in terms of ordering and use the generic one.

  The remaining two commits are not strictly fixes. They provide irqsave
  variants of atomic_dec_and_lock() and refcount_dec_and_lock(). These
  are required to merge the relevant updates and cleanups into different
  maintainer trees for 4.19, so routing them into mainline without
  actual users is the sanest approach.

  They should have been in -rc1, but last weekend I took the liberty to
  just avoid computers in order to regain some mental sanity"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/qspinlock: Fix build for anonymous union in older GCC compilers
  locking/lockdep: Do not record IRQ state within lockdep code
  locking/rwsem: Fix up_read_non_owner() warning with DEBUG_RWSEMS
  locking/refcounts: Implement refcount_dec_and_lock_irqsave()
  atomic: Add irqsave variant of atomic_dec_and_lock()
  alpha: Remove custom dec_and_lock() implementation
parents a43de489 6cc65be4

arch/alpha/Kconfig

+0 −5
Original line number Diff line number Diff line
@@ -555,11 +555,6 @@ config SMP 


	  If you don't know what to do here, say N.



config HAVE_DEC_LOCK

	bool

	depends on SMP

	default y



config NR_CPUS

	int "Maximum number of CPUs (2-32)"

	range 2 32

arch/alpha/lib/Makefile

+0 −2
Original line number Diff line number Diff line
@@ -35,8 +35,6 @@ lib-y = __divqu.o __remqu.o __divlu.o __remlu.o \ 
	callback_srm.o srm_puts.o srm_printk.o \

	fls.o



lib-$(CONFIG_SMP) += dec_and_lock.o



# The division routines are built from single source, with different defines.

AFLAGS___divqu.o = -DDIV

AFLAGS___remqu.o =       -DREM

arch/alpha/lib/dec_and_lock.c

deleted100644 → 0
+0 −44
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * arch/alpha/lib/dec_and_lock.c

 *

 * ll/sc version of atomic_dec_and_lock()

 * 

 */



#include <linux/spinlock.h>

#include <linux/atomic.h>

#include <linux/export.h>



  asm (".text					\n\

	.global _atomic_dec_and_lock		\n\

	.ent _atomic_dec_and_lock		\n\

	.align	4				\n\

_atomic_dec_and_lock:				\n\

	.prologue 0				\n\

1:	ldl_l	$1, 0($16)			\n\

	subl	$1, 1, $1			\n\

	beq	$1, 2f				\n\

	stl_c	$1, 0($16)			\n\

	beq	$1, 4f				\n\

	mb					\n\

	clr	$0				\n\

	ret					\n\

2:	br	$29, 3f				\n\

3:	ldgp	$29, 0($29)			\n\

	br	$atomic_dec_and_lock_1..ng	\n\

	.subsection 2				\n\

4:	br	1b				\n\

	.previous				\n\

	.end _atomic_dec_and_lock");



static int __used atomic_dec_and_lock_1(atomic_t *atomic, spinlock_t *lock)

{

	/* Slow path */

	spin_lock(lock);

	if (atomic_dec_and_test(atomic))

		return 1;

	spin_unlock(lock);

	return 0;

}

EXPORT_SYMBOL(_atomic_dec_and_lock);

include/asm-generic/qspinlock_types.h

+1 −1
Original line number Diff line number Diff line
@@ -63,7 +63,7 @@ typedef struct qspinlock { 
/*

 * Initializier

 */

#define	__ARCH_SPIN_LOCK_UNLOCKED	{ .val = ATOMIC_INIT(0) }

#define	__ARCH_SPIN_LOCK_UNLOCKED	{ { .val = ATOMIC_INIT(0) } }



/*

 * Bitfields in the atomic value:

include/linux/refcount.h

+3 −1
Original line number Diff line number Diff line
@@ -98,5 +98,7 @@ extern __must_check bool refcount_dec_if_one(refcount_t *r); 
extern __must_check bool refcount_dec_not_one(refcount_t *r);

extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock);

extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock);



extern __must_check bool refcount_dec_and_lock_irqsave(refcount_t *r,

						       spinlock_t *lock,

						       unsigned long *flags);

#endif /* _LINUX_REFCOUNT_H */