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05 April 2024, 19:05:47 UTC
Revision 04e36857d6747e4525e68c4292c081b795b48366 authored by Linus Torvalds on 19 November 2016, 00:45:21 UTC, committed by Linus Torvalds on 19 November 2016, 00:45:21 UTC 
Merge branch 'rc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild
 
Pull kbuild fixes from Michal Marek:
 "Here are some regression fixes for kbuild:

   - modversion support for exported asm symbols (Nick Piggin). The
     affected architectures need separate patches adding
     asm-prototypes.h.

   - fix rebuilds of lib-ksyms.o (Nick Piggin)

   - -fno-PIE builds (Sebastian Siewior and Borislav Petkov). This is
     not a kernel regression, but one of the Debian gcc package.
     Nevertheless, it's quite annoying, so I think it should go into
     mainline and stable now"

* 'rc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
  kbuild: Steal gcc's pie from the very beginning
  kbuild: be more careful about matching preprocessed asm ___EXPORT_SYMBOL
  x86/kexec: add -fno-PIE
  scripts/has-stack-protector: add -fno-PIE
  kbuild: add -fno-PIE
  kbuild: modversions for EXPORT_SYMBOL() for asm
  kbuild: prevent lib-ksyms.o rebuilds
2 parent s aad931a + c6a3855
Raw File
Tip revision: 04e36857d6747e4525e68c4292c081b795b48366 authored by Linus Torvalds on 19 November 2016, 00:45:21 UTC
Merge branch 'rc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild
Tip revision: 04e3685
dec_and_lock.c 
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>

/*
 * This is an implementation of the notion of "decrement a
 * reference count, and return locked if it decremented to zero".
 *
 * NOTE NOTE NOTE! This is _not_ equivalent to
 *
 *	if (atomic_dec_and_test(&atomic)) {
 *		spin_lock(&lock);
 *		return 1;
 *	}
 *	return 0;
 *
 * because the spin-lock and the decrement must be
 * "atomic".
 */
int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
{
	/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
	if (atomic_add_unless(atomic, -1, 1))
		return 0;

	/* Otherwise do it the slow way */
	spin_lock(lock);
	if (atomic_dec_and_test(atomic))
		return 1;
	spin_unlock(lock);
	return 0;
}

EXPORT_SYMBOL(_atomic_dec_and_lock);
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