From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Koschewski Subject: Re: [PATCH 1/1]mmc: fix division by zero when calculate mmc erase time Date: Thu, 24 Feb 2011 12:37:56 +0100 Message-ID: <20110224113756.GB7260@marc.osknowledge.org> References: <20110224111801.GA7169@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20110224111801.GA7169@intel.com> Sender: linux-kernel-owner@vger.kernel.org To: Chuanxiao Dong Cc: linux-mmc@vger.kernel.org, cjb@laptop.org, adrian.hunter@nokia.com, linus.walleij@linaro.org, linux-kernel@vger.kernel.org List-Id: linux-mmc@vger.kernel.org Hi, * Chuanxiao Dong [2011-02-24 19:18:01 +0800]: > Since if clock gating feature is enabled, the clock frequency may be zero when > host clock is gated. In such scenario, mmc_set_mmc_erase_timeout() may have a > division by zero bug. > > So this patch used mmc_host_clk_rate() to fix this. > > Signed-off-by: Chuanxiao Dong > --- > drivers/mmc/core/core.c | 10 ++++++++-- > 1 files changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c > index 34a7e8c..12d0eb8 100644 > --- a/drivers/mmc/core/core.c > +++ b/drivers/mmc/core/core.c > @@ -1201,8 +1201,14 @@ static void mmc_set_mmc_erase_timeout(struct mmc_card *card, > * less but not that much less, so fudge it by multiplying by 2. > */ > timeout_clks <<= 1; > - timeout_us += (timeout_clks * 1000) / > - (card->host->ios.clock / 1000); > + > + /* > + * at this moment, host controller maybe clock gated, so make > + * sure we can get a correct host clock freq. > + */ > + if (mmc_host_clk_rate(card->host)) > + timeout_us += (timeout_clks * 1000) / > + (mmc_host_clk_rate(card->host) / 1000); Why don't you just reuse mmc_host_clk_rate()'s result instead of calling it twice? Cheers, Marc > > erase_timeout = timeout_us / 1000; > > -- > 1.6.6.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > > -- Marc Koschewski