linux-kernel - [PATCH 5.4 104/123] drm/i915/gvt: Fix unnecessary schedule timer when no vGPU exits

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Message-Id: <20200317103318.214680634@linuxfoundation.org>
Date:   Tue, 17 Mar 2020 11:55:31 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Colin Xu <colin.xu@...el.com>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>
Subject: [PATCH 5.4 104/123] drm/i915/gvt: Fix unnecessary schedule timer when no vGPU exits

From: Zhenyu Wang <zhenyuw@...ux.intel.com>

commit 04d6067f1f19e70a418f92fa3170cf7fe53b7fdf upstream.

>>From commit f25a49ab8ab9 ("drm/i915/gvt: Use vgpu_lock to protect per
vgpu access") the vgpu idr destroy is moved later than vgpu resource
destroy, then it would fail to stop timer for schedule policy clean
which to check vgpu idr for any left vGPU. So this trys to destroy
vgpu idr earlier.

Cc: Colin Xu <colin.xu@...el.com>
Fixes: f25a49ab8ab9 ("drm/i915/gvt: Use vgpu_lock to protect per vgpu access")
Acked-by: Colin Xu <colin.xu@...el.com>
Signed-off-by: Zhenyu Wang <zhenyuw@...ux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200229055445.31481-1-zhenyuw@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/i915/gvt/vgpu.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/i915/gvt/vgpu.c
+++ b/drivers/gpu/drm/i915/gvt/vgpu.c
@@ -272,10 +272,17 @@ void intel_gvt_destroy_vgpu(struct intel
 {
 	struct intel_gvt *gvt = vgpu->gvt;
 
-	mutex_lock(&vgpu->vgpu_lock);
-
 	WARN(vgpu->active, "vGPU is still active!\n");
 
+	/*
+	 * remove idr first so later clean can judge if need to stop
+	 * service if no active vgpu.
+	 */
+	mutex_lock(&gvt->lock);
+	idr_remove(&gvt->vgpu_idr, vgpu->id);
+	mutex_unlock(&gvt->lock);
+
+	mutex_lock(&vgpu->vgpu_lock);
 	intel_gvt_debugfs_remove_vgpu(vgpu);
 	intel_vgpu_clean_sched_policy(vgpu);
 	intel_vgpu_clean_submission(vgpu);
@@ -290,7 +297,6 @@ void intel_gvt_destroy_vgpu(struct intel
 	mutex_unlock(&vgpu->vgpu_lock);
 
 	mutex_lock(&gvt->lock);
-	idr_remove(&gvt->vgpu_idr, vgpu->id);
 	if (idr_is_empty(&gvt->vgpu_idr))
 		intel_gvt_clean_irq(gvt);
 	intel_gvt_update_vgpu_types(gvt);