linux-kernel - [PATCH 08/10] staging: gasket: cleanup if dma_map_page fails in gasket_perform

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Message-Id: <20180917123905.213639-9-toddpoynor@gmail.com>
Date:   Mon, 17 Sep 2018 05:39:03 -0700
From:   Todd Poynor <toddpoynor@...il.com>
To:     Rob Springer <rspringer@...gle.com>,
        Ben Chan <benchan@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Nick Ewalt <nicholasewalt@...gle.com>,
        Todd Poynor <toddpoynor@...gle.com>
Subject: [PATCH 08/10] staging: gasket: cleanup if dma_map_page fails in gasket_perform_mapping

From: Nick Ewalt <nicholasewalt@...gle.com>

Previously pages would have never been unmapped in this case.

Signed-off-by: Nick Ewalt <nicholasewalt@...gle.com>
Signed-off-by: Todd Poynor <toddpoynor@...gle.com>
---
 drivers/staging/gasket/gasket_page_table.c | 33 +++++++++++++---------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/staging/gasket/gasket_page_table.c b/drivers/staging/gasket/gasket_page_table.c
index c1ce8f984f8e0..779ad2f23ef9b 100644
--- a/drivers/staging/gasket/gasket_page_table.c
+++ b/drivers/staging/gasket/gasket_page_table.c
@@ -433,6 +433,19 @@ static int is_coherent(struct gasket_page_table *pg_tbl, ulong host_addr)
 	return min <= host_addr && host_addr < max;
 }
 
+/* Safely return a page to the OS. */
+static bool gasket_release_page(struct page *page)
+{
+	if (!page)
+		return false;
+
+	if (!PageReserved(page))
+		SetPageDirty(page);
+	put_page(page);
+
+	return true;
+}
+
 /*
  * Get and map last level page table buffers.
  *
@@ -500,6 +513,13 @@ static int gasket_perform_mapping(struct gasket_page_table *pg_tbl,
 					(unsigned long long)ptes[i].dma_addr,
 					(void *)page_to_pfn(page),
 					(void *)page_to_phys(page));
+
+				/* clean up */
+				if (gasket_release_page(ptes[i].page))
+					--pg_tbl->num_active_pages;
+
+				memset(&ptes[i], 0,
+				       sizeof(struct gasket_page_table_entry));
 				return -1;
 			}
 		}
@@ -571,19 +591,6 @@ static int gasket_alloc_simple_entries(struct gasket_page_table *pg_tbl,
 	return 0;
 }
 
-/* Safely return a page to the OS. */
-static bool gasket_release_page(struct page *page)
-{
-	if (!page)
-		return false;
-
-	if (!PageReserved(page))
-		SetPageDirty(page);
-	put_page(page);
-
-	return true;
-}
-
 /*
  * Unmap and release mapped pages.
  * The page table mutex must be held by the caller.
-- 
2.19.0.397.gdd90340f6a-goog