linux-kernel - [PATCH] xen: gntalloc.c: Convert kmap() to kmap_local

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Message-Id: <20220418061927.6833-1-eng.alaamohamedsoliman.am@gmail.com>
Date:   Mon, 18 Apr 2022 08:19:27 +0200
From:   Alaa Mohamed <eng.alaamohamedsoliman.am@...il.com>
To:     outreachy@...ts.linux.dev
Cc:     boris.ostrovsky@...cle.com, jgross@...e.com,
        sstabellini@...nel.org, xen-devel@...ts.xenproject.org,
        linux-kernel@...r.kernel.org, ira.weiny@...el.com,
        eng.alaamohamedsoliman.am@...il.com
Subject: [PATCH] xen: gntalloc.c:  Convert kmap() to kmap_local_page()

The use of kmap() is being deprecated in favor of kmap_local_page()
where it is feasible.

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

Signed-off-by: Alaa Mohamed <eng.alaamohamedsoliman.am@...il.com>
---
 drivers/xen/gntalloc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
index 4849f94372a4..55acb32842a3 100644
--- a/drivers/xen/gntalloc.c
+++ b/drivers/xen/gntalloc.c
@@ -178,9 +178,9 @@ static void __del_gref(struct gntalloc_gref *gref)
 	unsigned long addr;
 
 	if (gref->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
-		uint8_t *tmp = kmap(gref->page);
+		uint8_t *tmp = kmap_local_page(gref->page);
 		tmp[gref->notify.pgoff] = 0;
-		kunmap(gref->page);
+		kunmap_local(tmp);
 	}
 	if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
 		notify_remote_via_evtchn(gref->notify.event);
-- 
2.35.2