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 <[email protected]>
---
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);
erase_timeout = timeout_us / 1000;
--
1.6.6.1
Hi,
* Chuanxiao Dong <[email protected]> [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 <[email protected]>
> ---
> 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 [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>
>
--
Marc Koschewski
> -----Original Message-----
> From: Marc Koschewski [mailto:[email protected]]
> Sent: Thursday, February 24, 2011 7:38 PM
> To: Dong, Chuanxiao
> Cc: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]
> Subject: Re: [PATCH 1/1]mmc: fix division by zero when calculate mmc erase time
>
> Hi,
>
> * Chuanxiao Dong <[email protected]> [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 <[email protected]>
> > ---
> > 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?
This is a incline function and just return host->ios.clock. Reuse mmc_host_clk_rate()'s result need to add a new variable to save the value.
Thanks
Chuanxiao
* Dong, Chuanxiao <[email protected]> [2011-02-24 20:09:59 +0800]:
>
>
> > -----Original Message-----
> > From: Marc Koschewski [mailto:[email protected]]
> > Sent: Thursday, February 24, 2011 7:38 PM
> > To: Dong, Chuanxiao
> > Cc: [email protected]; [email protected]; [email protected];
> > [email protected]; [email protected]
> > Subject: Re: [PATCH 1/1]mmc: fix division by zero when calculate mmc erase time
> >
> > Hi,
> >
> > * Chuanxiao Dong <[email protected]> [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 <[email protected]>
> > > ---
> > > 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?
> This is a incline function and just return host->ios.clock. Reuse mmc_host_clk_rate()'s result need to add a new variable to save the value.
It's not inline on trunk and it spinlocks.
drivers/mmc/core/host.c:195
194 */
195 unsigned int mmc_host_clk_rate(struct mmc_host *host)
196 {
Cheers,
Marc
>
> Thanks
> Chuanxiao
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>
>
--
Marc Koschewski
> -----Original Message-----
> From: Marc Koschewski [mailto:[email protected]]
> Sent: Thursday, February 24, 2011 8:23 PM
> To: Dong, Chuanxiao
> Cc: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]
> Subject: Re: [PATCH 1/1]mmc: fix division by zero when calculate mmc erase time
>
> * Dong, Chuanxiao <[email protected]> [2011-02-24 20:09:59 +0800]:
>
> >
> >
> > > -----Original Message-----
> > > From: Marc Koschewski [mailto:[email protected]]
> > > Sent: Thursday, February 24, 2011 7:38 PM
> > > To: Dong, Chuanxiao
> > > Cc: [email protected]; [email protected]; [email protected];
> > > [email protected]; [email protected]
> > > Subject: Re: [PATCH 1/1]mmc: fix division by zero when calculate mmc erase
> time
> > >
> > > Hi,
> > >
> > > * Chuanxiao Dong <[email protected]> [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 <[email protected]>
> > > > ---
> > > > 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?
> > This is a incline function and just return host->ios.clock. Reuse
> mmc_host_clk_rate()'s result need to add a new variable to save the value.
>
> It's not inline on trunk and it spinlocks.
>
> drivers/mmc/core/host.c:195
>
> 194 */
> 195 unsigned int mmc_host_clk_rate(struct mmc_host *host)
> 196 {
OK. With the clock gating framework enabled... I agree. So, what do you think? Add a new variable is better?
Thanks
Chuanxiao
* Dong, Chuanxiao <[email protected]> [2011-02-24 20:25:21 +0800]:
> > -----Original Message-----
> > From: Marc Koschewski [mailto:[email protected]]
> > Sent: Thursday, February 24, 2011 8:23 PM
> > To: Dong, Chuanxiao
> > Cc: [email protected]; [email protected]; [email protected];
> > [email protected]; [email protected]
> > Subject: Re: [PATCH 1/1]mmc: fix division by zero when calculate mmc erase time
> >
> > * Dong, Chuanxiao <[email protected]> [2011-02-24 20:09:59 +0800]:
> >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Marc Koschewski [mailto:[email protected]]
> > > > Sent: Thursday, February 24, 2011 7:38 PM
> > > > To: Dong, Chuanxiao
> > > > Cc: [email protected]; [email protected]; [email protected];
> > > > [email protected]; [email protected]
> > > > Subject: Re: [PATCH 1/1]mmc: fix division by zero when calculate mmc erase
> > time
> > > >
> > > > Hi,
> > > >
> > > > * Chuanxiao Dong <[email protected]> [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 <[email protected]>
> > > > > ---
> > > > > 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?
> > > This is a incline function and just return host->ios.clock. Reuse
> > mmc_host_clk_rate()'s result need to add a new variable to save the value.
> >
> > It's not inline on trunk and it spinlocks.
> >
> > drivers/mmc/core/host.c:195
> >
> > 194 */
> > 195 unsigned int mmc_host_clk_rate(struct mmc_host *host)
> > 196 {
> OK. With the clock gating framework enabled... I agree. So, what do you think? Add a new variable is better?
I personally would prefer the variable over the spinlock and function call, yes.
And calling the same method with the same parameters on a line and another
time on the next line is generally a bad idea I think. But maybe that's kind
of a 'taste', moreover. It just hit my eye when I saw it...
Cheers,
Marc
>
> Thanks
> Chuanxiao
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>
>
--
Marc Koschewski
2011/2/24 Chuanxiao Dong <[email protected]>:
> 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 <[email protected]>
Acked-by: Linus Walleij <[email protected]>
Actually I think these divide-by zero bugs were there before since clock
0 is perfectly legal, we just didn't trigger them before.
Yours,
Linus Walleij