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clk: fix reentrancy of clk_enable() on UP systems
Reentrant calls to clk_enable() are not working on UP systems. This is caused by the fact spin_trylock_irqsave() always returns true when CONFIG_SMP=n (and CONFIG_DEBUG_SPINLOCK=n) which causes the reference counting to not work correctly when clk_enable_lock() is called twice before clk_enable_unlock() is called (this happens when clk_enable() is called from within another clk_enable()). This fixes the problem by skipping the call to spin_trylock_irqsave() on UP systems and relying solely on reference counting. We also make sure to set flags in this case so that we are not returning an uninitialized value. Suggested-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: David Lechner <david@lechnology.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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@ -141,10 +141,18 @@ static unsigned long clk_enable_lock(void)
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{
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unsigned long flags;
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if (!spin_trylock_irqsave(&enable_lock, flags)) {
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/*
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* On UP systems, spin_trylock_irqsave() always returns true, even if
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* we already hold the lock. So, in that case, we rely only on
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* reference counting.
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*/
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if (!IS_ENABLED(CONFIG_SMP) ||
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!spin_trylock_irqsave(&enable_lock, flags)) {
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if (enable_owner == current) {
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enable_refcnt++;
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__acquire(enable_lock);
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if (!IS_ENABLED(CONFIG_SMP))
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local_save_flags(flags);
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return flags;
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}
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spin_lock_irqsave(&enable_lock, flags);
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