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@xxxxxx>
---
arch/arm/mach-omap2/clockdomain.c | 15 +++++++++++----
1 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/arch/arm/mach-omap2/clockdomain.c b/arch/arm/mach-omap2/clockdomain.c
index 8664f5a..173905d 100644
--- a/arch/arm/mach-omap2/clockdomain.c
+++ b/arch/arm/mach-omap2/clockdomain.c
@@ -914,15 +914,18 @@ 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);
@@ -939,15 +942,19 @@ 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);
--
1.7.4.1
--
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