linux-kernel - [PATCH v2] staging: rts5208: Convert kmap() to kmap_local

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Date:   Tue, 29 Mar 2022 07:55:39 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Benjamin Philip <benjamin.philip495@...il.com>,
        Bart Van Assche <bvanassche@....org>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Colin Ian King <colin.king@...el.com>,
        Samuel Sjöberg <info@...uelsjoberg.se>,
        Charlie Sands <sandsch@...thvilleschools.net>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        outreachy@...ts.linux.dev, ira.weiny@...el.com
Cc:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Subject: [PATCH v2] staging: rts5208: 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 rtsx_stor_access_xfer_buf() 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
helpers memcpy_to_page() and memcpy_from_page().

Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
---

v1 -> v2: Rework the commit message and use the appropriate helpers
instead of open coding the use of kmap_local_page()/kunmap_local_page().
(Many thanks to Ira Weiny <ira.weiny@...el.com>).

 drivers/staging/rts5208/rtsx_transport.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/rts5208/rtsx_transport.c b/drivers/staging/rts5208/rtsx_transport.c
index 805dc18fac0a..56b6cc845619 100644
--- a/drivers/staging/rts5208/rtsx_transport.c
+++ b/drivers/staging/rts5208/rtsx_transport.c
@@ -92,13 +92,11 @@ unsigned int rtsx_stor_access_xfer_buf(unsigned char *buffer,
 			while (sglen > 0) {
 				unsigned int plen = min(sglen, (unsigned int)
 						PAGE_SIZE - poff);
-				unsigned char *ptr = kmap(page);
 
 				if (dir == TO_XFER_BUF)
-					memcpy(ptr + poff, buffer + cnt, plen);
+					memcpy_to_page(page + poff, 0, buffer + cnt, plen);
 				else
-					memcpy(buffer + cnt, ptr + poff, plen);
-				kunmap(page);
+					memcpy_from_page(buffer + cnt, page + poff, 0, plen);
 
 				/* Start at the beginning of the next page */
 				poff = 0;
-- 
2.34.1