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(-)
--- a/drivers/soc/qcom/smp2p.c +++ b/drivers/soc/qcom/smp2p.c @@ -318,15 +318,16 @@ static int qcom_smp2p_inbound_entry(stru 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);