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().

Make a minor change to a comment related to scatter-gather.

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20220330143331.8306-1-fmdefrancesco@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/rts5208/rtsx_transport.c b/drivers/staging/rts5208/rtsx_transport.c
index 805dc18fac0aa65b67b5c44de10bc241835e875a..d5ad49de4c568544f96026574597f081d5564248 100644 (file)
--- a/drivers/staging/rts5208/rtsx_transport.c
+++ b/drivers/staging/rts5208/rtsx_transport.c
@@ -55,9 +55,9 @@ unsigned int rtsx_stor_access_xfer_buf(unsigned char *buffer,
                *offset += cnt;
 
        /*
-        * Using scatter-gather.  We have to go through the list one entry
-        * at a time.  Each s-g entry contains some number of pages, and
-        * each page has to be kmap()'ed separately.
+        * Using scatter-gather. We have to go through the list one entry
+        * at a time. Each s-g entry contains some number of pages which
+        * have to be copied one at a time.
         */
        } else {
                struct scatterlist *sg =
@@ -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, buffer + cnt, plen);
                                else
-                                       memcpy(buffer + cnt, ptr + poff, plen);
-                               kunmap(page);
+                                       memcpy_from_page(buffer + cnt, page, poff, plen);
 
                                /* Start at the beginning of the next page */
                                poff = 0;