[PATCH v2] staging: rts5208: Convert kmap() to kmap_local_page()

[PATCH v2] staging: rts5208: Convert kmap() to kmap_local_page()

[Fabio M. De Francesco]

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@gmail.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@intel.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

Re: [PATCH v2] staging: rts5208: Convert kmap() to kmap_local_page()

[Dan Carpenter]

On Tue, Mar 29, 2022 at 07:55:39AM +0200, Fabio M. De Francesco wrote:
> 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);

You meant:

	memcpy_to_page(page, poff, buffer + cnt, plen);

>  				else
> -					memcpy(buffer + cnt, ptr + poff, plen);
> -				kunmap(page);
> +					memcpy_from_page(buffer + cnt, page + poff, 0, plen);

Same.

regards,
dan carpenter

Re: [PATCH v2] staging: rts5208: Convert kmap() to kmap_local_page()

[Fabio M. De Francesco]

On marted? 29 marzo 2022 11:18:27 CEST Dan Carpenter wrote:
> On Tue, Mar 29, 2022 at 07:55:39AM +0200, Fabio M. De Francesco wrote:
> > 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);
> 
> You meant:
> 
> 	memcpy_to_page(page, poff, buffer + cnt, plen);
> 

Yes, correct. I meant exactly what you wrote.

It's the first time that I use these API and, after 30 seconds look at their 
prototypes, I thought that either have the same semantics.

I don't yet know if I'm wrong. However, even if either were correct, yours 
would be more consistent and elegant. Therefore, I am going to change these
calls and submit a v3.

Thanks for your review,

Fabio M. De Francesco

> >  				else
> > -					memcpy(buffer + cnt, ptr + poff, plen);
> > -				kunmap(page);
> > +					memcpy_from_page(buffer + cnt, page + poff, 0, plen);
> 
> Same.
> 
> regards,
> dan carpenter
> 
>