linux-kernel - [PATCH v1 1/6] drm/mediatek: put "event" in critical section

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Message-ID: <20191128024238.9399-2-bibby.hsieh@mediatek.com>
Date:   Thu, 28 Nov 2019 10:42:33 +0800
From:   Bibby Hsieh <bibby.hsieh@...iatek.com>
To:     David Airlie <airlied@...ux.ie>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-mediatek@...ts.infradead.org>
CC:     Philipp Zabel <p.zabel@...gutronix.de>,
        YT Shen <yt.shen@...iatek.com>,
        Thierry Reding <thierry.reding@...il.com>,
        CK Hu <ck.hu@...iatek.com>,
        <linux-arm-kernel@...ts.infradead.org>, <tfiga@...omium.org>,
        <drinkcat@...omium.org>, <linux-kernel@...r.kernel.org>,
        <srv_heupstream@...iatek.com>,
        Bibby Hsieh <bibby.hsieh@...iatek.com>
Subject: [PATCH v1 1/6] drm/mediatek: put "event" in critical section

The state->base.event variable would be access by thread context
in mtk_drm_crtc_atomic_begin() or by interrupt context in
mtk_drm_crtc_finish_page_flip(), so each part should be a critical
section. Fix it.

Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.")

Signed-off-by: Bibby Hsieh <bibby.hsieh@...iatek.com>
---
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
index 29d0582e90e9..71f4089a8117 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
@@ -483,12 +483,15 @@ static void mtk_drm_crtc_atomic_begin(struct drm_crtc *crtc,
 	if (mtk_crtc->event && state->base.event)
 		DRM_ERROR("new event while there is still a pending event\n");
 
+	spin_lock_irq(&crtc->dev->event_lock);
 	if (state->base.event) {
 		state->base.event->pipe = drm_crtc_index(crtc);
 		WARN_ON(drm_crtc_vblank_get(crtc) != 0);
+		WARN_ON(mtk_crtc->event);
 		mtk_crtc->event = state->base.event;
 		state->base.event = NULL;
 	}
+	spin_unlock_irq(&crtc->dev->event_lock);
 }
 
 static void mtk_drm_crtc_atomic_flush(struct drm_crtc *crtc,
-- 
2.18.0