[PATCH 18/19] drm/amd/display: Move dml2_destroy to non-FPU compilation unit

[Chenyu Chen <chen-yu.chen@amd.com>]

From: Rafal Ostrowski <rafal.ostrowski@amd.com>

On PREEMPT_RT kernels, vfree() can sleep because spin_lock is
converted to rt_mutex. dml2_destroy() calls vfree() while inside
an FPU-guarded region (preempt_count=2), which is illegal.

dml2_wrapper_fpu.c is compiled with CC_FLAGS_FPU which defines
_LINUX_FPU_COMPILATION_UNIT, making DC_RUN_WITH_PREEMPTION_ENABLED()
resolve to a no-op. This prevents the macro from cycling FPU
context off/on around vfree().

Move dml2_destroy() to dml2_wrapper.c (non-FPU compilation unit)
where DC_RUN_WITH_PREEMPTION_ENABLED() properly cycles DC_FP_END/
DC_FP_START around vfree(). This pairs it with dml2_allocate_memory()
which already lives there.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Rafal Ostrowski <rafal.ostrowski@amd.com>
Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com>
---
 .../drm/amd/display/dc/dml2_0/dml21/dml21_wrapper.c   |  4 ++--
 drivers/gpu/drm/amd/display/dc/dml2_0/dml2_wrapper.c  | 11 +++++++++++
 .../gpu/drm/amd/display/dc/dml2_0/dml2_wrapper_fpu.c  | 10 ----------
 3 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dml2_0/dml21/dml21_wrapper.c b/drivers/gpu/drm/amd/display/dc/dml2_0/dml21/dml21_wrapper.c
index 7398f8b69adb..8bed59e976d1 100644
--- a/drivers/gpu/drm/amd/display/dc/dml2_0/dml21/dml21_wrapper.c
+++ b/drivers/gpu/drm/amd/display/dc/dml2_0/dml21/dml21_wrapper.c
@@ -58,8 +58,8 @@ bool dml21_create(const struct dc *in_dc, struct dml2_context **dml_ctx, const s
 
 void dml21_destroy(struct dml2_context *dml2)
 {
-	vfree(dml2->v21.dml_init.dml2_instance);
-	vfree(dml2->v21.mode_programming.programming);
+	DC_RUN_WITH_PREEMPTION_ENABLED(vfree(dml2->v21.dml_init.dml2_instance));
+	DC_RUN_WITH_PREEMPTION_ENABLED(vfree(dml2->v21.mode_programming.programming));
 }
 
 void dml21_copy(struct dml2_context *dst_dml_ctx,
diff --git a/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_wrapper.c b/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_wrapper.c
index 93b7613fc4f2..1772e74349c7 100644
--- a/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_wrapper.c
+++ b/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_wrapper.c
@@ -108,6 +108,17 @@ bool dml2_create(const struct dc *in_dc, const struct dml2_configuration_options
 	return true;
 }
 
+void dml2_destroy(struct dml2_context *dml2)
+{
+	if (!dml2)
+		return;
+
+	if (dml2->architecture == dml2_architecture_21)
+		dml21_destroy(dml2);
+
+	DC_RUN_WITH_PREEMPTION_ENABLED(vfree(dml2));
+}
+
 void dml2_reinit(const struct dc *in_dc,
 				 const struct dml2_configuration_options *config,
 				 struct dml2_context **dml2)
diff --git a/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_wrapper_fpu.c b/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_wrapper_fpu.c
index 66624cfc27b1..a14e3004a7b7 100644
--- a/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_wrapper_fpu.c
+++ b/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_wrapper_fpu.c
@@ -548,16 +548,6 @@ void dml2_apply_debug_options(const struct dc *dc, struct dml2_context *dml2)
 	}
 }
 
-void dml2_destroy(struct dml2_context *dml2)
-{
-	if (!dml2)
-		return;
-
-	if (dml2->architecture == dml2_architecture_21)
-		dml21_destroy(dml2);
-	vfree(dml2);
-}
-
 void dml2_extract_dram_and_fclk_change_support(struct dml2_context *dml2,
 	unsigned int *fclk_change_support, unsigned int *dram_clk_change_support)
 {
-- 
2.43.0