From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCHv5 02/10] ARM: OMAP3+: voltage: add support for voltagedomain usecounts
Date: Tue, 25 Sep 2012 10:41:00 +0100 [thread overview]
Message-ID: <20120925094100.GK31374@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1348565565-14744-3-git-send-email-t-kristo@ti.com>
On Tue, Sep 25, 2012 at 12:32:37PM +0300, Tero Kristo wrote:
> diff --git a/arch/arm/mach-omap2/powerdomain.c b/arch/arm/mach-omap2/powerdomain.c
> index ba49029..ca54aec 100644
> --- a/arch/arm/mach-omap2/powerdomain.c
> +++ b/arch/arm/mach-omap2/powerdomain.c
> @@ -1475,10 +1477,16 @@ int pwrdm_state_switch(struct powerdomain *pwrdm)
> */
> void pwrdm_clkdm_enable(struct powerdomain *pwrdm)
> {
> + unsigned long flags;
> +
> if (!pwrdm)
> return;
>
> - atomic_inc(&pwrdm->usecount);
> + if (atomic_inc_return(&pwrdm->usecount) == 1) {
> + spin_lock_irqsave(&pwrdm->lock, flags);
> + voltdm_pwrdm_enable(pwrdm->voltdm.ptr);
> + spin_unlock_irqrestore(&pwrdm->lock, flags);
> + }
This looks like the classic "I like atomic types because they have magic
properties" brain-deadness.
What would happen to users of this if you had this sequence:
pwrdm->usecount starts off as 1.
Thread0 Thread1
atomic_inc_return() (returns 1)
atomic_inc_return() (returns 2)
starts using stuff in power domain
spin_lock_irqsave()
voltdm_pwrdm_enable()
spin_unlock_irqrestore()
?
next prev parent reply other threads:[~2012-09-25 9:41 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-25 9:32 [PATCHv5 00/10] ARM: OMAP: PM usecounting changes Tero Kristo
2012-09-25 9:32 ` [PATCHv5 01/10] ARM: OMAP3+: voltage/pwrdm/clkdm/clock add recursive usecount tracking Tero Kristo
2012-09-25 9:32 ` [PATCHv5 02/10] ARM: OMAP3+: voltage: add support for voltagedomain usecounts Tero Kristo
2012-09-25 9:41 ` Russell King - ARM Linux [this message]
2012-09-25 12:02 ` Tero Kristo
2012-09-25 9:32 ` [PATCHv5 03/10] ARM: OMAP3: add manual control for mpu / core pwrdm usecounting Tero Kristo
2012-09-25 9:32 ` [PATCHv5 04/10] ARM: OMAP3: set autoidle flag for sdrc_ick Tero Kristo
2012-09-25 9:32 ` [PATCHv5 05/10] ARM: OMAP: clockdomain: add support for preventing autodep delete Tero Kristo
2012-09-25 9:32 ` [PATCHv5 06/10] ARM: OMAP3: do not delete per_clkdm autodeps during idle Tero Kristo
2012-09-25 9:32 ` [PATCHv5 07/10] ARM: OMAP4: clock data: set autoidle flag for dss_fck Tero Kristo
2012-09-25 9:32 ` [PATCHv5 08/10] ARM: OMAP4: hwmod: add support for hwmod autoidle flag Tero Kristo
2012-09-25 9:32 ` [PATCHv5 09/10] ARM: OMAP4: hwmod data: set mpu hwmod modulemode to hwauto Tero Kristo
2012-09-25 9:32 ` [PATCHv5 10/10] ARM: OMAP4: clock data: flag hw controlled clocks as autoidle Tero Kristo
2012-09-25 10:26 ` [PATCHv5 00/10] ARM: OMAP: PM usecounting changes Rajendra Nayak
2012-09-25 11:53 ` Tero Kristo
2012-09-25 12:23 ` Rajendra Nayak
2012-09-25 14:17 ` Tero Kristo
2012-09-26 4:15 ` Rajendra Nayak
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