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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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0c1f845772
In intel_wakeref_auto, we use refcount_inc_not_zero to detect the first
use and initialise the timer. On doing so, we have to avoid using
refcount_inc on that zero count as the debug code flags that as an
error:
refcount_t: increment on 0; use-after-free.
Rearrange the code so that if we know the count is 0 and we are
initialising, we explicitly set it to 1.
Fixes: b27e35ae5b ("drm/i915: Keep user GGTT alive for a minimum of 250ms")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528154053.22004-1-chris@chris-wilson.co.uk
139 lines
3.2 KiB
C
139 lines
3.2 KiB
C
/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright © 2019 Intel Corporation
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*/
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#include "intel_drv.h"
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#include "intel_wakeref.h"
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static void rpm_get(struct drm_i915_private *i915, struct intel_wakeref *wf)
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{
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wf->wakeref = intel_runtime_pm_get(i915);
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}
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static void rpm_put(struct drm_i915_private *i915, struct intel_wakeref *wf)
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{
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intel_wakeref_t wakeref = fetch_and_zero(&wf->wakeref);
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intel_runtime_pm_put(i915, wakeref);
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GEM_BUG_ON(!wakeref);
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}
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int __intel_wakeref_get_first(struct drm_i915_private *i915,
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struct intel_wakeref *wf,
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int (*fn)(struct intel_wakeref *wf))
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{
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/*
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* Treat get/put as different subclasses, as we may need to run
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* the put callback from under the shrinker and do not want to
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* cross-contanimate that callback with any extra work performed
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* upon acquiring the wakeref.
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*/
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mutex_lock_nested(&wf->mutex, SINGLE_DEPTH_NESTING);
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if (!atomic_read(&wf->count)) {
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int err;
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rpm_get(i915, wf);
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err = fn(wf);
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if (unlikely(err)) {
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rpm_put(i915, wf);
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mutex_unlock(&wf->mutex);
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return err;
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}
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smp_mb__before_atomic(); /* release wf->count */
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}
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atomic_inc(&wf->count);
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mutex_unlock(&wf->mutex);
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return 0;
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}
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int __intel_wakeref_put_last(struct drm_i915_private *i915,
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struct intel_wakeref *wf,
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int (*fn)(struct intel_wakeref *wf))
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{
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int err;
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err = fn(wf);
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if (likely(!err))
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rpm_put(i915, wf);
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else
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atomic_inc(&wf->count);
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mutex_unlock(&wf->mutex);
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return err;
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}
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void __intel_wakeref_init(struct intel_wakeref *wf, struct lock_class_key *key)
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{
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__mutex_init(&wf->mutex, "wakeref", key);
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atomic_set(&wf->count, 0);
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wf->wakeref = 0;
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}
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static void wakeref_auto_timeout(struct timer_list *t)
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{
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struct intel_wakeref_auto *wf = from_timer(wf, t, timer);
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intel_wakeref_t wakeref;
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unsigned long flags;
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if (!refcount_dec_and_lock_irqsave(&wf->count, &wf->lock, &flags))
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return;
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wakeref = fetch_and_zero(&wf->wakeref);
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spin_unlock_irqrestore(&wf->lock, flags);
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intel_runtime_pm_put(wf->i915, wakeref);
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}
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void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
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struct drm_i915_private *i915)
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{
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spin_lock_init(&wf->lock);
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timer_setup(&wf->timer, wakeref_auto_timeout, 0);
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refcount_set(&wf->count, 0);
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wf->wakeref = 0;
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wf->i915 = i915;
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}
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void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout)
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{
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unsigned long flags;
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if (!timeout) {
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if (del_timer_sync(&wf->timer))
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wakeref_auto_timeout(&wf->timer);
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return;
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}
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/* Our mission is that we only extend an already active wakeref */
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assert_rpm_wakelock_held(wf->i915);
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if (!refcount_inc_not_zero(&wf->count)) {
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spin_lock_irqsave(&wf->lock, flags);
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if (!refcount_inc_not_zero(&wf->count)) {
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GEM_BUG_ON(wf->wakeref);
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wf->wakeref = intel_runtime_pm_get_if_in_use(wf->i915);
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refcount_set(&wf->count, 1);
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}
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spin_unlock_irqrestore(&wf->lock, flags);
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}
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/*
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* If we extend a pending timer, we will only get a single timer
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* callback and so need to cancel the local inc by running the
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* elided callback to keep the wf->count balanced.
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*/
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if (mod_timer(&wf->timer, jiffies + timeout))
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wakeref_auto_timeout(&wf->timer);
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}
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void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf)
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{
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intel_wakeref_auto(wf, 0);
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GEM_BUG_ON(wf->wakeref);
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}
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