From: Chris Wilson Date: Tue, 11 Apr 2017 10:13:38 +0000 (+0100) Subject: drm/i915: Acquire uncore.lock over intel_uncore_wait_for_register() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=0564654340e2776843ade007c1aaa8e8f30dd147;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git drm/i915: Acquire uncore.lock over intel_uncore_wait_for_register() We acquire the forcewake and use I915_READ_FW instead for the atomic wait within intel_uncore_wait_for_register. However, this still leaves us vulnerable to concurrent mmio access to the register, which can cause system hangs on gen7. The protection is to acquire uncore.lock around each register, so lets add it back. v2: Wrap __intel_wait_for_register_fw() to re-use its atomic wait_for loop and spare adding another for ourselves. v3: Add might_sleep() annotation Signed-off-by: Chris Wilson Cc: Michal Wajdeczko Cc: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/20170411101340.31994-3-chris@chris-wilson.co.uk Reviewed-by: Tvrtko Ursulin --- diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c index dded42db880b..fb38c7692fc2 100644 --- a/drivers/gpu/drm/i915/intel_uncore.c +++ b/drivers/gpu/drm/i915/intel_uncore.c @@ -1662,14 +1662,22 @@ int intel_wait_for_register(struct drm_i915_private *dev_priv, u32 value, unsigned int timeout_ms) { - unsigned fw = intel_uncore_forcewake_for_reg(dev_priv, reg, FW_REG_READ); int ret; - intel_uncore_forcewake_get(dev_priv, fw); - ret = wait_for_us((I915_READ_FW(reg) & mask) == value, 2); - intel_uncore_forcewake_put(dev_priv, fw); + might_sleep(); + + spin_lock_irq(&dev_priv->uncore.lock); + intel_uncore_forcewake_get__locked(dev_priv, fw); + + ret = __intel_wait_for_register_fw(dev_priv, + reg, mask, value, + 2, 0, NULL); + + intel_uncore_forcewake_put__locked(dev_priv, fw); + spin_unlock_irq(&dev_priv->uncore.lock); + if (ret) ret = wait_for((I915_READ_NOTRACE(reg) & mask) == value, timeout_ms);