lkml.org 
[lkml]   [2012]   [May]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH] MMC: core: cap MMC card timeouts at 2 seconds.
    Date
    From: "Torne (Richard Coles)" <torne@google.com>

    MMC CSD info can specify very large, ridiculous timeouts, big enough to
    overflow timeout_ns on 32-bit machines. This can result in the card
    timing out on every operation because the wrapped timeout value is far
    too small.

    Fix the overflow by capping the result at 2 seconds. Cards specifying
    longer timeouts are almost certainly insane, and host controllers
    generally cannot support timeouts that long in any case.

    2 seconds should be plenty of time for any card to actually function;
    the timeout calculation code is already using 1 second as a "worst case"
    timeout for cards running in SPI mode.

    Signed-off-by: Torne (Richard Coles) <torne@google.com>
    ---
    drivers/mmc/core/core.c | 11 ++++++++++-
    1 files changed, 10 insertions(+), 1 deletions(-)

    diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
    index 0b6141d..3b4a9fc 100644
    --- a/drivers/mmc/core/core.c
    +++ b/drivers/mmc/core/core.c
    @@ -512,7 +512,16 @@ void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card)
    if (data->flags & MMC_DATA_WRITE)
    mult <<= card->csd.r2w_factor;

    - data->timeout_ns = card->csd.tacc_ns * mult;
    + /*
    + * The timeout in nanoseconds may overflow with some cards. Cap it at
    + * two seconds both to avoid the overflow and also because host
    + * controllers cannot generally generate timeouts that long anyway.
    + */
    + if (card->csd.tacc_ns <= (2 * NSEC_PER_SEC) / mult)
    + data->timeout_ns = card->csd.tacc_ns * mult;
    + else
    + data->timeout_ns = 2 * NSEC_PER_SEC;
    +
    data->timeout_clks = card->csd.tacc_clks * mult;

    /*
    --
    1.7.7.3


    \
     
     \ /
      Last update: 2012-05-29 11:41    [W:0.024 / U:59.540 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site