linux-kernel - [PATCH 1/2] drm/lima: fix shared irq handling on driver remove

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Date: Tue,  2 Apr 2024 00:43:28 +0200
From: Erico Nunes <nunes.erico@...il.com>
To: Qiang Yu <yuq825@...il.com>,
	anarsoul@...il.com,
	dri-devel@...ts.freedesktop.org,
	lima@...ts.freedesktop.org
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	linux-kernel@...r.kernel.org,
	Erico Nunes <nunes.erico@...il.com>
Subject: [PATCH 1/2] drm/lima: fix shared irq handling on driver remove

lima uses a shared interrupt, so the interrupt handlers must be prepared
to be called at any time. At driver removal time, the clocks are
disabled early and the interrupts stay registered until the very end of
the remove process due to the devm usage.
This is potentially a bug as the interrupts access device registers
which assumes clocks are enabled. A crash can be triggered by removing
the driver in a kernel with CONFIG_DEBUG_SHIRQ enabled.
This patch frees the interrupts at each lima device finishing callback
so that the handlers are already unregistered by the time we fully
disable clocks.

Signed-off-by: Erico Nunes <nunes.erico@...il.com>
---
 drivers/gpu/drm/lima/lima_gp.c  | 2 ++
 drivers/gpu/drm/lima/lima_mmu.c | 5 +++++
 drivers/gpu/drm/lima/lima_pp.c  | 4 ++++
 3 files changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/lima/lima_gp.c b/drivers/gpu/drm/lima/lima_gp.c
index 6b354e2fb61d..14c39be8da90 100644
--- a/drivers/gpu/drm/lima/lima_gp.c
+++ b/drivers/gpu/drm/lima/lima_gp.c
@@ -338,7 +338,9 @@ int lima_gp_init(struct lima_ip *ip)
 
 void lima_gp_fini(struct lima_ip *ip)
 {
+	struct lima_device *dev = ip->dev;
 
+	devm_free_irq(dev->dev, ip->irq, ip);
 }
 
 int lima_gp_pipe_init(struct lima_device *dev)
diff --git a/drivers/gpu/drm/lima/lima_mmu.c b/drivers/gpu/drm/lima/lima_mmu.c
index e18317c5ca8c..6611e2836bf0 100644
--- a/drivers/gpu/drm/lima/lima_mmu.c
+++ b/drivers/gpu/drm/lima/lima_mmu.c
@@ -118,7 +118,12 @@ int lima_mmu_init(struct lima_ip *ip)
 
 void lima_mmu_fini(struct lima_ip *ip)
 {
+	struct lima_device *dev = ip->dev;
+
+	if (ip->id == lima_ip_ppmmu_bcast)
+		return;
 
+	devm_free_irq(dev->dev, ip->irq, ip);
 }
 
 void lima_mmu_flush_tlb(struct lima_ip *ip)
diff --git a/drivers/gpu/drm/lima/lima_pp.c b/drivers/gpu/drm/lima/lima_pp.c
index d0d2db0ef1ce..84bec163c9ed 100644
--- a/drivers/gpu/drm/lima/lima_pp.c
+++ b/drivers/gpu/drm/lima/lima_pp.c
@@ -286,7 +286,9 @@ int lima_pp_init(struct lima_ip *ip)
 
 void lima_pp_fini(struct lima_ip *ip)
 {
+	struct lima_device *dev = ip->dev;
 
+	devm_free_irq(dev->dev, ip->irq, ip);
 }
 
 int lima_pp_bcast_resume(struct lima_ip *ip)
@@ -319,7 +321,9 @@ int lima_pp_bcast_init(struct lima_ip *ip)
 
 void lima_pp_bcast_fini(struct lima_ip *ip)
 {
+	struct lima_device *dev = ip->dev;
 
+	devm_free_irq(dev->dev, ip->irq, ip);
 }
 
 static int lima_pp_task_validate(struct lima_sched_pipe *pipe,
-- 
2.44.0