From 52e3632ea603ef92757d5d0dedcd9fc8643445e3 Mon Sep 17 00:00:00 2001 From: Roel Kluin Date: Mon, 22 Jun 2009 18:41:56 +0100 Subject: [PATCH] serial: fix off by one errors 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 Acked-by: David S. Miller Acked-by: Maciej W. Rozycki Signed-off-by: Andrew Morton Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- 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 a4fb343a08d..319e8b83f6b 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 a94a2ab4b57..1df5325faab 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 9e6a873f820..d8c2809b1ab 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); -- 2.41.0