soc: qcom: smp2p: Safely acquire spinlock without IRQs
commit5.4-rM2-2.2.x-imx-squashedfc3e62e25c
upstream. smp2p_update_bits() should disable interrupts when it acquires its spinlock. This is important because without the _irqsave, a priority inversion can occur. This function is called both with interrupts enabled in qcom_q6v5_request_stop(), and with interrupts disabled in ipa_smp2p_panic_notifier(). IRQ handling of spinlocks should be consistent to avoid the panic notifier deadlocking because it's sitting on the thread that's already got the lock via _request_stop(). Found via lockdep. Cc: stable@vger.kernel.org Fixes:50e9964141
("soc: qcom: smp2p: Qualcomm Shared Memory Point to Point") Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Signed-off-by: Evan Green <evgreen@chromium.org> Link: https://lore.kernel.org/r/20200929133040.RESEND.1.Ideabf6dcdfc577cf39ce3d95b0e4aa1ac8b38f0c@changeid Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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ddcb518dee
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b22739509d
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@ -318,15 +318,16 @@ static int qcom_smp2p_inbound_entry(struct qcom_smp2p *smp2p,
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static int smp2p_update_bits(void *data, u32 mask, u32 value)
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static int smp2p_update_bits(void *data, u32 mask, u32 value)
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{
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{
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struct smp2p_entry *entry = data;
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struct smp2p_entry *entry = data;
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unsigned long flags;
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u32 orig;
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u32 orig;
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u32 val;
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u32 val;
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spin_lock(&entry->lock);
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spin_lock_irqsave(&entry->lock, flags);
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val = orig = readl(entry->value);
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val = orig = readl(entry->value);
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val &= ~mask;
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val &= ~mask;
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val |= value;
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val |= value;
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writel(val, entry->value);
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writel(val, entry->value);
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spin_unlock(&entry->lock);
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spin_unlock_irqrestore(&entry->lock, flags);
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if (val != orig)
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if (val != orig)
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qcom_smp2p_kick(entry->smp2p);
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qcom_smp2p_kick(entry->smp2p);
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