linux-kernel - [PATCH 3/8] serial: tegra: check the count and read if any from dma

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 5 May 2015 15:17:54 +0100
From:	Jon Hunter <jonathanh@...dia.com>
To:	Laxman Dewangan <ldewangan@...dia.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>
CC:	<linux-serial@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	Shardar Shariff Md <smohammed@...dia.com>,
	Jon Hunter <jonathanh@...dia.com>
Subject: [PATCH 3/8] serial: tegra: check the count and read if any from dma

From: Shardar Shariff Md <smohammed@...dia.com>

It is only necessary to read data from the dma buffer when the count
value is non-zero and hence, tegra_uart_copy_rx_to_tty() so only be
called when this is the case.

Although, this was being tested for in two places, there is a third
place where this was not tested. However, instead of adding another
if-statement prior to calling tegra_uart_copy_rx_to_tty(), move the test
inside the function.

Signed-off-by: Shardar Shariff Md <smohammed@...dia.com>
[jonathanh@...dia.com: Re-worked patch to move the check for the count
 value inside the function tegra_uart_copy_rx_to_tty(). Updated
 changelog with more commentary.]
Signed-off-by: Jon Hunter <jonathanh@...dia.com>
---
 drivers/tty/serial/serial-tegra.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index 0d9d7ceb1dbb..a53899c47e60 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -554,6 +554,10 @@ static void tegra_uart_copy_rx_to_tty(struct tegra_uart_port *tup,
 {
 	int copied;
 
+	/* If count is zero, then there is no data to be copied */
+	if (!count)
+		return;
+
 	tup->uport.icount.rx += count;
 	if (!tty) {
 		dev_err(tup->uport.dev, "No tty port\n");
@@ -588,8 +592,7 @@ static void tegra_uart_rx_dma_complete(void *args)
 		set_rts(tup, false);
 
 	/* If we are here, DMA is stopped */
-	if (count)
-		tegra_uart_copy_rx_to_tty(tup, port, count);
+	tegra_uart_copy_rx_to_tty(tup, port, count);
 
 	tegra_uart_handle_rx_pio(tup, port);
 	if (tty) {
@@ -626,8 +629,7 @@ static void tegra_uart_handle_rx_dma(struct tegra_uart_port *tup,
 	count = tup->rx_bytes_requested - state.residue;
 
 	/* If we are here, DMA is stopped */
-	if (count)
-		tegra_uart_copy_rx_to_tty(tup, port, count);
+	tegra_uart_copy_rx_to_tty(tup, port, count);
 
 	tegra_uart_handle_rx_pio(tup, port);
 	if (tty) {
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/