linux-kernel - [PATCH] staging: vc04_services: Convert kmap() to kmap_local

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Message-Id: <20220330191414.23141-1-fmdefrancesco@gmail.com>
Date:   Wed, 30 Mar 2022 21:14:14 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        bcm-kernel-feedback-list@...adcom.com,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        ira.weiny@...el.com, outreachy@...ts.linux.dev
Cc:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Subject: [PATCH] staging: vc04_services: Convert kmap() to kmap_local_page()

The use of kmap() is being deprecated in favor of kmap_local_page()
where it is feasible. In file interface/vchiq_arm/vchiq_arm.c,
function free_pagelist() calls kmap() / kunmap() from two places.

With kmap_local_page(), the mapping is per thread, CPU local and not
globally visible. Therefore, free_pagelist() is a function where the
use of kmap_local_page() in place of kmap() is correctly suited.

Convert to kmap_local_page() but, instead of open coding it, use the
memcpy_to_page() helper.

Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
---
 .../vc04_services/interface/vchiq_arm/vchiq_arm.c   | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index f0bfacfdea80..efb1383b5218 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -431,21 +431,18 @@ free_pagelist(struct vchiq_pagelist_info *pagelistinfo,
 			if (head_bytes > actual)
 				head_bytes = actual;
 
-			memcpy((char *)kmap(pages[0]) +
+			memcpy_to_page(pages[0],
 				pagelist->offset,
 				fragments,
 				head_bytes);
-			kunmap(pages[0]);
 		}
 		if ((actual >= 0) && (head_bytes < actual) &&
-		    (tail_bytes != 0)) {
-			memcpy((char *)kmap(pages[num_pages - 1]) +
-				((pagelist->offset + actual) &
-				(PAGE_SIZE - 1) & ~(g_cache_line_size - 1)),
+		    (tail_bytes != 0))
+			memcpy_to_page(pages[num_pages - 1],
+				(pagelist->offset + actual) &
+				(PAGE_SIZE - 1) & ~(g_cache_line_size - 1),
 				fragments + g_cache_line_size,
 				tail_bytes);
-			kunmap(pages[num_pages - 1]);
-		}
 
 		down(&g_free_fragments_mutex);
 		*(char **)fragments = g_free_fragments;
-- 
2.34.1