drm/i915/shrinker: Wrap need_resched() inside preempt-disable
In order for us to successfully detect the end of a timeslice, preemption must be disabled. Otherwise, inside the loop we may be preempted many times without our noticing, and each time our timeslice will be reset, invalidating need_resched() Reported-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Reported-by: Tomi Sarvela <tomi.p.sarvela@intel.com> Fixes:290271de34
("drm/i915: Spin for struct_mutex inside shrinker") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: <drm-intel-fixes@lists.freedesktop.org> # v4.13-rc1+ Link: https://patchwork.freedesktop.org/patch/msgid/20170804104135.26805-1-chris@chris-wilson.co.uk Tested-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> (cherry picked from commit6cb0c6ad9e
) Signed-off-by: Jani Nikula <jani.nikula@intel.com>
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@ -43,16 +43,21 @@ static bool shrinker_lock(struct drm_i915_private *dev_priv, bool *unlock)
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return true;
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case MUTEX_TRYLOCK_FAILED:
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*unlock = false;
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preempt_disable();
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do {
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cpu_relax();
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if (mutex_trylock(&dev_priv->drm.struct_mutex)) {
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case MUTEX_TRYLOCK_SUCCESS:
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*unlock = true;
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return true;
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break;
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}
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} while (!need_resched());
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preempt_enable();
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return *unlock;
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return false;
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case MUTEX_TRYLOCK_SUCCESS:
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*unlock = true;
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return true;
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}
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BUG();
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