linux-kernel - [PATCH v2] spi: detect wrong transfer->len values

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Date:	Mon, 26 Sep 2011 10:55:18 +0200
From:	Michael Thalmeier <michael.thalmeier@...e.at>
To:	Grant Likely <grant.likely@...retlab.ca>
Cc:	spi-devel-general@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] spi: detect wrong transfer->len values

From: Helmut Raiger <helmut.raiger@...e.at>

Instead of returning an error, which could have unknown consequences for
different drivers, just use dev_WARN_ONCE to output a warning.

Signed-off-by: Michael Thalmeier <michael.thalmeier@...e.at>
---
 drivers/spi/spi.c |   15 ++++++++++++++-
 1 files changed, 14 insertions(+), 1 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 4d1b9f5..49f6666 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -760,6 +760,20 @@ EXPORT_SYMBOL_GPL(spi_setup);
 static int __spi_async(struct spi_device *spi, struct spi_message *message)
 {
 	struct spi_master *master = spi->master;
+	struct spi_transfer *xfer;
+
+	/* check if number of bytes relates to bits per word mode */
+	list_for_each_entry(xfer, &message->transfers, transfer_list) {
+		u8 bpw = xfer->bits_per_word ?
+				xfer->bits_per_word : spi->bits_per_word;
+
+		dev_WARN_ONCE(&spi->dev,
+				((bpw == 16 && (xfer->len & 1)) ||
+				(bpw == 32 && (xfer->len & 3))),
+				"incorrect number of bytes detected: "
+				"bpw=%u xfer->len=%u", bpw, xfer->len);
+
+	}
 
 	/* Half-duplex links include original MicroWire, and ones with
 	 * only one data pin like SPI_3WIRE (switches direction) or where
@@ -768,7 +782,6 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message)
 	 */
 	if ((master->flags & SPI_MASTER_HALF_DUPLEX)
 			|| (spi->mode & SPI_3WIRE)) {
-		struct spi_transfer *xfer;
 		unsigned flags = master->flags;
 
 		list_for_each_entry(xfer, &message->transfers, transfer_list) {
-- 
1.7.6.2



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