linux-kernel - [PATCH v1 1/1] drm/xe: fix the ERR_PTR() returned on failure to allocate tiny pt

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Message-ID: <20241121212057.1526634-2-mtodorovac69@gmail.com>
Date: Thu, 21 Nov 2024 22:20:58 +0100
From: Mirsad Todorovac <mtodorovac69@...il.com>
To: Rodrigo Vivi <rodrigo.vivi@...el.com>,
	intel-xe@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Cc: Lucas De Marchi <lucas.demarchi@...el.com>,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Mirsad Todorovac <mtodorovac69@...il.com>,
	Matthew Brost <matthew.brost@...el.com>,
	Matthew Auld <matthew.auld@...el.com>,
	Matt Roper <matthew.d.roper@...el.com>,
	Francois Dugast <francois.dugast@...el.com>,
	Philippe Lecluse <philippe.lecluse@...el.com>,
	Nirmoy Das <nirmoy.das@...el.com>,
	Jani Nikula <jani.nikula@...el.com>,
	José Roberto de Souza <jose.souza@...el.com>,
	Faith Ekstrand <faith.ekstrand@...labora.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Akshata Jahagirdar <akshata.jahagirdar@...el.com>,
	David Kershner <david.kershner@...el.com>
Subject: [PATCH v1 1/1] drm/xe: fix the ERR_PTR() returned on failure to allocate tiny pt

Running coccinelle spatch gave the following warning:

./drivers/gpu/drm/xe/tests/xe_migrate.c:226:5-11: inconsistent IS_ERR and PTR_ERR on line 228.

The code reports PTR_ERR(pt) when IS_ERR(tiny) is checked:

→ 211         pt = xe_bo_create_pin_map(xe, tile, m->q->vm, XE_PAGE_SIZE,
  212                                   ttm_bo_type_kernel,
  213                                   XE_BO_FLAG_VRAM_IF_DGFX(tile) |
  214                                   XE_BO_FLAG_PINNED);
  215         if (IS_ERR(pt)) {
  216                 KUNIT_FAIL(test, "Failed to allocate fake pt: %li\n",
  217                            PTR_ERR(pt));
  218                 goto free_big;
  219         }
  220
  221         tiny = xe_bo_create_pin_map(xe, tile, m->q->vm,
→ 222                                     2 * SZ_4K,
  223                                     ttm_bo_type_kernel,
  224                                     XE_BO_FLAG_VRAM_IF_DGFX(tile) |
  225                                     XE_BO_FLAG_PINNED);
→ 226         if (IS_ERR(tiny)) {
→ 227                 KUNIT_FAIL(test, "Failed to allocate fake pt: %li\n",
→ 228                            PTR_ERR(pt));
  229                 goto free_pt;
  230         }

Now, the IS_ERR(tiny) and the corresponding PTR_ERR(pt) do not match.

Returning PTR_ERR(tiny), as the last failed function call, seems logical.

Fixes: dd08ebf6c3525 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Cc: Matthew Brost <matthew.brost@...el.com>
Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
Cc: Matthew Auld <matthew.auld@...el.com>
Cc: Matt Roper <matthew.d.roper@...el.com>
Cc: "Thomas Hellström" <thomas.hellstrom@...ux.intel.com>
Cc: Francois Dugast <francois.dugast@...el.com>
Cc: Lucas De Marchi <lucas.demarchi@...el.com>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Cc: Philippe Lecluse <philippe.lecluse@...el.com>
Cc: Nirmoy Das <nirmoy.das@...el.com>
Cc: Jani Nikula <jani.nikula@...el.com>
Cc: José Roberto de Souza <jose.souza@...el.com>
Cc: David Airlie <airlied@...il.com>
Cc: Maxime Ripard <mripard@...nel.org>
Cc: Faith Ekstrand <faith.ekstrand@...labora.com>
Cc: Daniel Vetter <daniel.vetter@...ll.ch>
Cc: Simona Vetter <simona@...ll.ch>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: Thomas Zimmermann <tzimmermann@...e.de>
Cc: Akshata Jahagirdar <akshata.jahagirdar@...el.com>
Cc: David Kershner <david.kershner@...el.com>
Cc: intel-xe@...ts.freedesktop.org
Cc: dri-devel@...ts.freedesktop.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Mirsad Todorovac <mtodorovac69@...il.com>
---
 v1:
	There is also the logical problem which this patch developer is not qualified to fix:
	first the fake pt tries to allocate size of (1 << (XE_PT_SHIFT=12)) = 4096 bytes,
	then "tiny pt" tries to allocate 2 * SZ_4K, twice as much. Is this what was meant
	to accomplish?

	drivers/gpu/drm/xe/xe_bo.h#L46:
	#define XE_PTE_SHIFT			12
	#define XE_PAGE_SIZE			(1 << XE_PTE_SHIFT)

	include/linux/sizes.h#L23:
	#define SZ_4K				0x00001000

 drivers/gpu/drm/xe/tests/xe_migrate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/tests/xe_migrate.c b/drivers/gpu/drm/xe/tests/xe_migrate.c
index 1a192a2a941b..3bbdb362d6f0 100644
--- a/drivers/gpu/drm/xe/tests/xe_migrate.c
+++ b/drivers/gpu/drm/xe/tests/xe_migrate.c
@@ -224,8 +224,8 @@ static void xe_migrate_sanity_test(struct xe_migrate *m, struct kunit *test)
 				    XE_BO_FLAG_VRAM_IF_DGFX(tile) |
 				    XE_BO_FLAG_PINNED);
 	if (IS_ERR(tiny)) {
-		KUNIT_FAIL(test, "Failed to allocate fake pt: %li\n",
-			   PTR_ERR(pt));
+		KUNIT_FAIL(test, "Failed to allocate tiny fake pt: %li\n",
+			   PTR_ERR(tiny));
 		goto free_pt;
 	}
 
-- 
2.43.0