Revision 9822393d23ba9129396ab9308dbb8ce10ae74751 authored by Dave Airlie on 26 March 2015, 21:39:45 UTC, committed by Dave Airlie on 26 March 2015, 21:39:45 UTC
This should cover the final warnings in -rc5 with two more backports from our development branch (drm-intel-next-queued). They're the ones from Daniel and Damien, with references to the reports. This is on top of drm-fixes because of the dependency on the two earlier fixes not yet in Linus' tree. There's an additional regression fix from Chris. * tag 'drm-intel-fixes-2015-03-26' of git://anongit.freedesktop.org/drm-intel: drm/i915: Fixup legacy plane->crtc link for initial fb config drm/i915: Fix atomic state when reusing the firmware fb drm/i915: Keep ring->active_list and ring->requests_list consistent
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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