linux-kernel - [PATCH 4.2.y-ckt 206/268] mtd: nand: denali: add missing nand_release() call in denali

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Message-Id: <1453926929-17663-207-git-send-email-kamal@canonical.com>
Date:	Wed, 27 Jan 2016 12:34:27 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	Brian Norris <computersforpeace@...il.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 206/268] mtd: nand: denali: add missing nand_release() call in denali_remove()

4.2.8-ckt3 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Boris BREZILLON <boris.brezillon@...e-electrons.com>

commit 320092a05dab2f44819c42f33d6b51efb6c474f2 upstream.

Unregister the NAND device from the NAND subsystem when removing a denali
NAND controller, otherwise the MTD attached to the NAND device is still
exposed by the MTD layer, and accesses to this device will likely crash
the system.

Fixes: 2a0a288ec258 ("mtd: denali: split the generic driver and PCI layer")
Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
Acked-by: Dinh Nguyen <dinguyen@...nsource.altera.com>
Signed-off-by: Brian Norris <computersforpeace@...il.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/mtd/nand/denali.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index 870c7fc..f229554 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -1613,9 +1613,16 @@ EXPORT_SYMBOL(denali_init);
 /* driver exit point */
 void denali_remove(struct denali_nand_info *denali)
 {
+	/*
+	 * Pre-compute DMA buffer size to avoid any problems in case
+	 * nand_release() ever changes in a way that mtd->writesize and
+	 * mtd->oobsize are not reliable after this call.
+	 */
+	int bufsize = denali->mtd.writesize + denali->mtd.oobsize;
+
+	nand_release(&denali->mtd);
 	denali_irq_cleanup(denali->irq, denali);
-	dma_unmap_single(denali->dev, denali->buf.dma_buf,
-			 denali->mtd.writesize + denali->mtd.oobsize,
+	dma_unmap_single(denali->dev, denali->buf.dma_buf, bufsize,
 			 DMA_BIDIRECTIONAL);
 }
 EXPORT_SYMBOL(denali_remove);
-- 
1.9.1