From: Evan Green <evgreen@chromium.org> commit fc3e62e25c3896855b7c3d72df19ca6be3459c9f 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: 50e99641413e7 ("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.Ideabf6dcdfc577cf39ce3d95b... Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/soc/qcom/smp2p.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/soc/qcom/smp2p.c b/drivers/soc/qcom/smp2p.c index c22503cd1edf..7908e7f2850f 100644 --- a/drivers/soc/qcom/smp2p.c +++ b/drivers/soc/qcom/smp2p.c @@ -326,15 +326,16 @@ static int qcom_smp2p_inbound_entry(struct qcom_smp2p *smp2p, static int smp2p_update_bits(void *data, u32 mask, u32 value) { struct smp2p_entry *entry = data; + unsigned long flags; u32 orig; u32 val; - spin_lock(&entry->lock); + spin_lock_irqsave(&entry->lock, flags); val = orig = readl(entry->value); val &= ~mask; val |= value; writel(val, entry->value); - spin_unlock(&entry->lock); + spin_unlock_irqrestore(&entry->lock, flags); if (val != orig) qcom_smp2p_kick(entry->smp2p); -- 2.25.1