linux-kernel - [PATCH 4.2 083/258] spi: bcm2835: BUG: fix wrong use of PAGE

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Message-Id: <20151018014734.156493442@linuxfoundation.org>
Date:	Sat, 17 Oct 2015 18:56:36 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, robert@...um.co.nz,
	Martin Sperl <kernel@...tin.sperl.org>,
	Mark Brown <broonie@...nel.org>
Subject: [PATCH 4.2 083/258] spi: bcm2835: BUG: fix wrong use of PAGE_MASK

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

------------------

From: Martin Sperl <kernel@...tin.sperl.org>

commit 2a3fffd45822070309bcf0b1e1dae624d633824a upstream.

There is a bug in the alignment checking of transfers,
that results in DMA not being used for un-aligned
transfers that do not cross page-boundries, which is valid.

This is due to a missconception of the meaning PAGE_MASK
when implementing that check originally - (PAGE_SIZE - 1)
should have been used instead.

Also fixes a copy/paste error.

Reported-by: <robert@...um.co.nz>
Signed-off-by: Martin Sperl <kernel@...tin.sperl.org>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/spi/spi-bcm2835.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -386,14 +386,14 @@ static bool bcm2835_spi_can_dma(struct s
 	/* otherwise we only allow transfers within the same page
 	 * to avoid wasting time on dma_mapping when it is not practical
 	 */
-	if (((size_t)tfr->tx_buf & PAGE_MASK) + tfr->len > PAGE_SIZE) {
+	if (((size_t)tfr->tx_buf & (PAGE_SIZE - 1)) + tfr->len > PAGE_SIZE) {
 		dev_warn_once(&spi->dev,
 			      "Unaligned spi tx-transfer bridging page\n");
 		return false;
 	}
-	if (((size_t)tfr->rx_buf & PAGE_MASK) + tfr->len > PAGE_SIZE) {
+	if (((size_t)tfr->rx_buf & (PAGE_SIZE - 1)) + tfr->len > PAGE_SIZE) {
 		dev_warn_once(&spi->dev,
-			      "Unaligned spi tx-transfer bridging page\n");
+			      "Unaligned spi rx-transfer bridging page\n");
 		return false;
 	}
 


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