https://github.com/torvalds/linux
Revision 4fb68f9789cf80817c16462f070a9107febc1478 authored by Linus Torvalds on 12 November 2016, 00:25:28 UTC, committed by Linus Torvalds on 12 November 2016, 00:25:28 UTC
Pull drm fixes from Dave Airlie:
 "AMD, radeon, i915, imx, msm and udl fixes:

   - amdgpu/radeon have a number of power management regressions and
     fixes along with some better error checking

   - imx has a single regression fix

   - udl has a single kmalloc instead of stack for usb control msg fix

   - msm has some fixes for modesetting bugs and regressions

   - i915 has a one fix for a Sandybridge regression along with some
     others for DP audio.

  They all seem pretty okay at this stage, we've got one MST fix I know
  going through process for i915, but I expect it'll be next week"

* tag 'drm-fixes-for-v4.9-rc5' of git://people.freedesktop.org/~airlied/linux: (30 commits)
  drm/udl: make control msg static const. (v2)
  drm/amd/powerplay: implement get_clock_by_type for iceland.
  drm/amd/powerplay/smu7: fix checks in smu7_get_evv_voltages (v2)
  drm/amd/powerplay: update phm_get_voltage_evv_on_sclk for iceland
  drm/amd/powerplay: propagate errors in phm_get_voltage_evv_on_sclk
  drm/imx: disable planes before DC
  drm/amd/powerplay: return false instead of -EINVAL
  drm/amdgpu/powerplay/smu7: fix unintialized data usage
  drm/amdgpu: fix crash in acp_hw_fini
  drm/i915: Limit Valleyview and earlier to only using mappable scanout
  drm/i915: Round tile chunks up for constructing partial VMAs
  drm/i915/dp: Extend BDW DP audio workaround to GEN9 platforms
  drm/i915/dp: BDW cdclk fix for DP audio
  drm/i915/vlv: Prevent enabling hpd polling in late suspend
  drm/i915: Respect alternate_ddc_pin for all DDI ports
  drm/msm: Fix error handling crashes seen when VRAM allocation fails
  drm/msm/mdp5: 8x16 actually has 8 mixer stages
  drm/msm/mdp5: no scaling support on RGBn pipes for 8x16
  drm/msm/mdp5: handle non-fullscreen base plane case
  drm/msm: Set CLK_IGNORE_UNUSED flag for PLL clocks
  ...
2 parent s b8b73df + 24399f4
Raw File
Tip revision: 4fb68f9789cf80817c16462f070a9107febc1478 authored by Linus Torvalds on 12 November 2016, 00:25:28 UTC
Merge tag 'drm-fixes-for-v4.9-rc5' of git://people.freedesktop.org/~airlied/linux
Tip revision: 4fb68f9
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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