linux-kernel - [PATCH 2/2] drm/imagination: avoid -Woverflow warning

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Message-Id: <20231129113825.2961913-2-arnd@kernel.org>
Date:   Wed, 29 Nov 2023 12:33:08 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Frank Binns <frank.binns@...tec.com>,
        Donald Robson <donald.robson@...tec.com>,
        Matt Coster <matt.coster@...tec.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        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>,
        Sarah Walker <sarah.walker@...tec.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] drm/imagination: avoid -Woverflow warning

From: Arnd Bergmann <arnd@...db.de>

The array size calculation in pvr_vm_mips_fini() appears to be incorrect based on
taking the size of the pointer rather than the size of the array, which manifests
as a warning about signed integer overflow:

In file included from include/linux/kernel.h:16,
                 from drivers/gpu/drm/imagination/pvr_rogue_fwif.h:10,
                 from drivers/gpu/drm/imagination/pvr_ccb.h:7,
                 from drivers/gpu/drm/imagination/pvr_device.h:7,
                 from drivers/gpu/drm/imagination/pvr_vm_mips.c:4:
drivers/gpu/drm/imagination/pvr_vm_mips.c: In function 'pvr_vm_mips_fini':
include/linux/array_size.h:11:25: error: overflow in conversion from 'long unsigned int' to 'int' changes value from '18446744073709551615' to '-1' [-Werror=overflow]
   11 | #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
      |                         ^
drivers/gpu/drm/imagination/pvr_vm_mips.c:106:24: note: in expansion of macro 'ARRAY_SIZE'
  106 |         for (page_nr = ARRAY_SIZE(mips_data->pt_pages) - 1; page_nr >= 0; page_nr--) {
      |                        ^~~~~~~~~~

Just use the number of array elements directly here, and in the corresponding
init function for consistency.

Fixes: 927f3e0253c1 ("drm/imagination: Implement MIPS firmware processor and MMU support")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/gpu/drm/imagination/pvr_vm_mips.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/imagination/pvr_vm_mips.c b/drivers/gpu/drm/imagination/pvr_vm_mips.c
index 7268cf6e630b..6c2e4cc4e6db 100644
--- a/drivers/gpu/drm/imagination/pvr_vm_mips.c
+++ b/drivers/gpu/drm/imagination/pvr_vm_mips.c
@@ -46,7 +46,7 @@ pvr_vm_mips_init(struct pvr_device *pvr_dev)
 	if (!mips_data)
 		return -ENOMEM;
 
-	for (page_nr = 0; page_nr < ARRAY_SIZE(mips_data->pt_pages); page_nr++) {
+	for (page_nr = 0; page_nr < PVR_MIPS_PT_PAGE_COUNT; page_nr++) {
 		mips_data->pt_pages[page_nr] = alloc_page(GFP_KERNEL | __GFP_ZERO);
 		if (!mips_data->pt_pages[page_nr]) {
 			err = -ENOMEM;
@@ -103,7 +103,7 @@ pvr_vm_mips_fini(struct pvr_device *pvr_dev)
 	int page_nr;
 
 	vunmap(mips_data->pt);
-	for (page_nr = ARRAY_SIZE(mips_data->pt_pages) - 1; page_nr >= 0; page_nr--) {
+	for (page_nr = PVR_MIPS_PT_PAGE_COUNT - 1; page_nr >= 0; page_nr--) {
 		dma_unmap_page(from_pvr_device(pvr_dev)->dev,
 			       mips_data->pt_dma_addr[page_nr], PAGE_SIZE, DMA_TO_DEVICE);
 
-- 
2.39.2