From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: torvalds@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: [PATCH 04/15] serial: fix off by one errors
Date: Mon, 22 Jun 2009 18:41:56 +0100 [thread overview]
Message-ID: <20090622174152.25341.62978.stgit@t61.ukuu.org.uk> (raw)
In-Reply-To: <20090622172929.25341.31151.stgit@t61.ukuu.org.uk>
From: Roel Kluin <roel.kluin@gmail.com>
In zs_console_putchar() occurs:
if (zs_transmit_drain(zport, irq))
write_zsdata(zport, ch);
However if in zs_transmit_drain() no empty Tx Buffer occurs, limit reaches
-1 => true, and the write still occurs.
This patch changes postfix to prefix decrements in this and similar
functions to prevent similar mistakes in the future. This decreases the
iterations with one but the chosen loop count was arbitrary anyway.
In sunhv limit reaches -1, not 0, so the test is off by one.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alan Cox <alan@linux.intel.com>
---
drivers/serial/sb1250-duart.c | 6 +++---
drivers/serial/sunhv.c | 2 +-
drivers/serial/zs.c | 6 +++---
3 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/serial/sb1250-duart.c b/drivers/serial/sb1250-duart.c
index a4fb343..319e8b8 100644
--- a/drivers/serial/sb1250-duart.c
+++ b/drivers/serial/sb1250-duart.c
@@ -204,7 +204,7 @@ static int sbd_receive_drain(struct sbd_port *sport)
{
int loops = 10000;
- while (sbd_receive_ready(sport) && loops--)
+ while (sbd_receive_ready(sport) && --loops)
read_sbdchn(sport, R_DUART_RX_HOLD);
return loops;
}
@@ -218,7 +218,7 @@ static int __maybe_unused sbd_transmit_drain(struct sbd_port *sport)
{
int loops = 10000;
- while (!sbd_transmit_ready(sport) && loops--)
+ while (!sbd_transmit_ready(sport) && --loops)
udelay(2);
return loops;
}
@@ -232,7 +232,7 @@ static int sbd_line_drain(struct sbd_port *sport)
{
int loops = 10000;
- while (!sbd_transmit_empty(sport) && loops--)
+ while (!sbd_transmit_empty(sport) && --loops)
udelay(2);
return loops;
}
diff --git a/drivers/serial/sunhv.c b/drivers/serial/sunhv.c
index a94a2ab..1df5325 100644
--- a/drivers/serial/sunhv.c
+++ b/drivers/serial/sunhv.c
@@ -461,7 +461,7 @@ static void sunhv_console_write_paged(struct console *con, const char *s, unsign
break;
udelay(1);
}
- if (limit <= 0)
+ if (limit < 0)
break;
page_bytes -= written;
ra += written;
diff --git a/drivers/serial/zs.c b/drivers/serial/zs.c
index 9e6a873..d8c2809 100644
--- a/drivers/serial/zs.c
+++ b/drivers/serial/zs.c
@@ -231,7 +231,7 @@ static int zs_receive_drain(struct zs_port *zport)
{
int loops = 10000;
- while ((read_zsreg(zport, R0) & Rx_CH_AV) && loops--)
+ while ((read_zsreg(zport, R0) & Rx_CH_AV) && --loops)
read_zsdata(zport);
return loops;
}
@@ -241,7 +241,7 @@ static int zs_transmit_drain(struct zs_port *zport, int irq)
struct zs_scc *scc = zport->scc;
int loops = 10000;
- while (!(read_zsreg(zport, R0) & Tx_BUF_EMP) && loops--) {
+ while (!(read_zsreg(zport, R0) & Tx_BUF_EMP) && --loops) {
zs_spin_unlock_cond_irq(&scc->zlock, irq);
udelay(2);
zs_spin_lock_cond_irq(&scc->zlock, irq);
@@ -254,7 +254,7 @@ static int zs_line_drain(struct zs_port *zport, int irq)
struct zs_scc *scc = zport->scc;
int loops = 10000;
- while (!(read_zsreg(zport, R1) & ALL_SNT) && loops--) {
+ while (!(read_zsreg(zport, R1) & ALL_SNT) && --loops) {
zs_spin_unlock_cond_irq(&scc->zlock, irq);
udelay(2);
zs_spin_lock_cond_irq(&scc->zlock, irq);
next prev parent reply other threads:[~2009-06-22 16:44 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-22 17:30 [PATCH 00/15] Serial/tty follow up fixes for 2.6,31 Alan Cox
2009-06-22 17:31 ` [PATCH 01/15] bfin_jtag_comm: clean up printk usage Alan Cox
2009-06-22 17:37 ` [PATCH 02/15] serial: bfin_5xx: add missing spin_lock init Alan Cox
2009-06-22 17:41 ` [PATCH 03/15] serial: bfin_5xx: fix building as module when early printk is enabled Alan Cox
2009-06-22 17:41 ` Alan Cox [this message]
2009-06-22 17:42 ` [PATCH 05/15] n_r3964: fix lock imbalance Alan Cox
2009-06-22 17:42 ` [PATCH 06/15] pcmcia/cm4000: " Alan Cox
2009-06-22 17:42 ` [PATCH 07/15] vt_ioctl: " Alan Cox
2009-06-22 17:42 ` [PATCH 08/15] ppp: Fix throttling bugs Alan Cox
2009-06-22 17:42 ` [PATCH 09/15] tty: fix some bogns in the serqt_usb2 driver Alan Cox
2009-06-22 17:42 ` [PATCH 10/15] serial@ add OMAP wakeup-enable register Alan Cox
2009-06-22 17:42 ` [PATCH 11/15] serial: samsung.c: mark s3c24xx_serial_remove as __devexit Alan Cox
2009-06-22 17:42 ` [PATCH 12/15] tty: n_hdlc add buffer flushing Alan Cox
2009-06-22 17:43 ` [PATCH 13/15] timbuart: Fix for tx_empty Alan Cox
2009-06-22 17:43 ` [PATCH 14/15] msm_serial: serial driver for MSM7K onboard serial peripheral Alan Cox
2009-06-22 17:43 ` [PATCH 15/15] msm: fixups to match current code Alan Cox
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