linux-kernel - [PATCH] drm/i915/gt: Avoid redundant pointer validity check

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Date:   Sat, 4 Feb 2023 01:00:27 +0530
From:   Deepak R Varma <drv@...lo.com>
To:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Cc:     Saurabh Singh Sengar <ssengar@...rosoft.com>,
        Praveen Kumar <kumarpraveen@...ux.microsoft.com>,
        Deepak R Varma <drv@...lo.com>
Subject: [PATCH] drm/i915/gt: Avoid redundant pointer validity check

The macro definition of gen6_for_all_pdes() expands to a for loop such
that it breaks when the page table is null. Hence there is no need to
again test validity of the page table entry pointers in the pde list.
This change is identified using itnull.cocci semantic patch.

Signed-off-by: Deepak R Varma <drv@...lo.com>
---
Please note: Proposed change is compile tested only.

 drivers/gpu/drm/i915/gt/gen6_ppgtt.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
index 5aaacc53fa4c..787b9e6d9f59 100644
--- a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
+++ b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
@@ -258,8 +258,7 @@ static void gen6_ppgtt_free_pd(struct gen6_ppgtt *ppgtt)
 	u32 pde;
 
 	gen6_for_all_pdes(pt, pd, pde)
-		if (pt)
-			free_pt(&ppgtt->base.vm, pt);
+		free_pt(&ppgtt->base.vm, pt);
 }
 
 static void gen6_ppgtt_cleanup(struct i915_address_space *vm)
@@ -304,7 +303,7 @@ static void pd_vma_unbind(struct i915_address_space *vm,
 
 	/* Free all no longer used page tables */
 	gen6_for_all_pdes(pt, ppgtt->base.pd, pde) {
-		if (!pt || atomic_read(&pt->used))
+		if (atomic_read(&pt->used))
 			continue;
 
 		free_pt(&ppgtt->base.vm, pt);
-- 
2.34.1