lkml.org 
[lkml]   [2009]   [Jun]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 04/15] serial: fix off by one errors
    Date
    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);


    \
     
     \ /
      Last update: 2009-06-22 18:47    [W:0.022 / U:75.108 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site