From f4c3bc8fe0c80baafea0ae672823f603d10e388b Mon Sep 17 00:00:00 2001 From: Evan Green Date: Thu, 7 Jan 2021 07:47:32 +0000 Subject: [PATCH] soc: qcom: smp2p: Safely acquire spinlock without IRQs stable inclusion from stable-5.10.4 commit 3bcf02208e9e5687389efa6773cdbc5d5afa3835 bugzilla: 46903 -------------------------------- 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 Reviewed-by: Stephen Boyd Signed-off-by: Evan Green Link: https://lore.kernel.org/r/20200929133040.RESEND.1.Ideabf6dcdfc577cf39ce3d95b0e4aa1ac8b38f0c@changeid Signed-off-by: Bjorn Andersson Signed-off-by: Greg Kroah-Hartman Signed-off-by: Chen Jun Acked-by: Xie XiuQi --- 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 07183d731d74..a9709aae54ab 100644 --- a/drivers/soc/qcom/smp2p.c +++ b/drivers/soc/qcom/smp2p.c @@ -318,15 +318,16 @@ 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); -- GitLab