linux-kernel - [PATCH 17/18] staging: gasket: don't release coherent mappings

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Message-Id: <20180714055816.223754-18-toddpoynor@gmail.com>
Date:   Fri, 13 Jul 2018 22:58:15 -0700
From:   Todd Poynor <toddpoynor@...il.com>
To:     Rob Springer <rspringer@...gle.com>,
        John Joseph <jnjoseph@...gle.com>,
        Ben Chan <benchan@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Zhongze Hu <frankhu@...omium.org>, Simon Que <sque@...omium.org>,
        Dmitry Torokhov <dtor@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Todd Poynor <toddpoynor@...gle.com>
Subject: [PATCH 17/18] staging: gasket: don't release coherent mappings

From: Todd Poynor <toddpoynor@...gle.com>

coherent address mappings aren't backed by a struct page, don't need to
be released, and don't count as an active page in the page table
bookkeeping.

Signed-off-by: Simon Que <sque@...omium.org>
Signed-off-by: Todd Poynor <toddpoynor@...gle.com>
---
 drivers/staging/gasket/gasket_page_table.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/gasket/gasket_page_table.c b/drivers/staging/gasket/gasket_page_table.c
index d7600d8e385f..9a4a81c010f9 100644
--- a/drivers/staging/gasket/gasket_page_table.c
+++ b/drivers/staging/gasket/gasket_page_table.c
@@ -1248,7 +1248,7 @@ static void gasket_perform_unmapping(
 				dma_unmap_page(pg_tbl->device, ptes[i].dma_addr,
 					       PAGE_SIZE, DMA_FROM_DEVICE);
 			}
-			if (gasket_release_page(ptes[i].page))
+			if (ptes[i].page && gasket_release_page(ptes[i].page))
 				--pg_tbl->num_active_pages;
 		}
 		ptes[i].status = PTE_FREE;
-- 
2.18.0.203.gfac676dfb9-goog