linux-kernel - [PATCH] staging: vc04_services: Convert get_user_pages*() --> pin_user

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Date:   Wed,  3 Jun 2020 00:24:17 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     gregkh@...uxfoundation.org, jamal.k.shareef@...il.com,
        dan.carpenter@...cle.com, marcgonzalez@...gle.com,
        hariprasad.kelam@...il.com, tasman@...flabs.com,
        nachukannan@...il.com
Cc:     bcm-kernel-feedback-list@...adcom.com,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org,
        Souptick Joarder <jrdr.linux@...il.com>,
        John Hubbard <jhubbard@...dia.com>
Subject: [PATCH] staging: vc04_services: Convert get_user_pages*() --> pin_user_pages*()

In 2019, we introduced pin_user_pages*() and now we are converting
get_user_pages*() to the new API as appropriate. [1] & [2] could
be referred for more information.

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
        https://lwn.net/Articles/807108/

Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
Cc: John Hubbard <jhubbard@...dia.com>
---
Hi,

I'm compile tested this, but unable to run-time test, so any testing
help is much appriciated.

 .../vc04_services/interface/vchiq_arm/vchiq_2835_arm.c   | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
index 38a13e4..4616013 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
@@ -287,12 +287,8 @@ int vchiq_dump_platform_state(void *dump_context)
 			     pagelistinfo->num_pages, pagelistinfo->dma_dir);
 	}
 
-	if (pagelistinfo->pages_need_release) {
-		unsigned int i;
-
-		for (i = 0; i < pagelistinfo->num_pages; i++)
-			put_page(pagelistinfo->pages[i]);
-	}
+	if (pagelistinfo->pages_need_release)
+		unpin_user_pages(pagelistinfo->pages, pagelistinfo->num_pages);
 
 	dma_free_coherent(g_dev, pagelistinfo->pagelist_buffer_size,
 			  pagelistinfo->pagelist, pagelistinfo->dma_addr);
@@ -395,7 +391,7 @@ int vchiq_dump_platform_state(void *dump_context)
 		}
 		/* do not try and release vmalloc pages */
 	} else {
-		actual_pages = get_user_pages_fast(
+		actual_pages = pin_user_pages_fast(
 					  (unsigned long)buf & PAGE_MASK,
 					  num_pages,
 					  type == PAGELIST_READ,
@@ -407,10 +403,8 @@ int vchiq_dump_platform_state(void *dump_context)
 				       __func__, actual_pages, num_pages);
 
 			/* This is probably due to the process being killed */
-			while (actual_pages > 0) {
-				actual_pages--;
-				put_page(pages[actual_pages]);
-			}
+			if (actual_pages > 0)
+				unpin_user_pages(pages, actual_pages);
 			cleanup_pagelistinfo(pagelistinfo);
 			return NULL;
 		}
-- 
1.9.1