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ARM: OMAP: clockdomain: Fix locking on _clkdm_clk_hwmod_enable / disable 

Previously the code only acquired spinlock after increasing / decreasing
the usecount value, which is wrong. This leaves a small window where
a task switch may occur between the check of the usecount and the actual
wakeup / sleep of the domain. Fixed by moving the spinlock locking before
the usecount access. Left the usecount as atomic_t if someone wants an
easy access to the parameter through atomic_read.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Acked-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
This commit is contained in:
Tero Kristo 2012-09-25 19:05:32 +03:00 committed by Tony Lindgren
parent 49c58e8202
commit 64e29fd5ed
1 changed files with 11 additions and 4 deletions
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15
arch/arm/mach-omap2/clockdomain.c
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@ -925,15 +925,18 @@ static int _clkdm_clk_hwmod_enable(struct clockdomain *clkdm)
if (!clkdm || !arch_clkdm || !arch_clkdm->clkdm_clk_enable)
return -EINVAL;
spin_lock_irqsave(&clkdm->lock, flags);
/*
* For arch's with no autodeps, clkcm_clk_enable
* should be called for every clock instance or hwmod that is
* enabled, so the clkdm can be force woken up.
*/
if ((atomic_inc_return(&clkdm->usecount) > 1) && autodeps)
if ((atomic_inc_return(&clkdm->usecount) > 1) && autodeps) {
spin_unlock_irqrestore(&clkdm->lock, flags);
return 0;
}
spin_lock_irqsave(&clkdm->lock, flags);
arch_clkdm->clkdm_clk_enable(clkdm);
pwrdm_state_switch(clkdm->pwrdm.ptr);
spin_unlock_irqrestore(&clkdm->lock, flags);
@ -950,15 +953,19 @@ static int _clkdm_clk_hwmod_disable(struct clockdomain *clkdm)
if (!clkdm || !arch_clkdm || !arch_clkdm->clkdm_clk_disable)
return -EINVAL;
spin_lock_irqsave(&clkdm->lock, flags);
if (atomic_read(&clkdm->usecount) == 0) {
spin_unlock_irqrestore(&clkdm->lock, flags);
WARN_ON(1); /* underflow */
return -ERANGE;
}
if (atomic_dec_return(&clkdm->usecount) > 0)
if (atomic_dec_return(&clkdm->usecount) > 0) {
spin_unlock_irqrestore(&clkdm->lock, flags);
return 0;
}
spin_lock_irqsave(&clkdm->lock, flags);
arch_clkdm->clkdm_clk_disable(clkdm);
pwrdm_state_switch(clkdm->pwrdm.ptr);
spin_unlock_irqrestore(&clkdm->lock, flags);