From: Stephen Boyd <swboyd@chromium.org>
To: Bjorn Andersson <bjorn.andersson@linaro.org>,
Evan Green <evgreen@chromium.org>
Cc: Markus Elfring <elfring@users.sourceforge.net>,
Evan Green <evgreen@chromium.org>, Andy Gross <agross@kernel.org>,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH] soc: qcom: smp2p: Safely acquire spinlock without IRQs
Date: Fri, 16 Oct 2020 09:48:29 -0700 [thread overview]
Message-ID: <160286690900.884498.13659438662199129460@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <20200929133040.RESEND.1.Ideabf6dcdfc577cf39ce3d95b0e4aa1ac8b38f0c@changeid>
Quoting Evan Green (2020-09-29 13:30:57)
> 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.
>
> Fixes: 50e99641413e7 ("soc: qcom: smp2p: Qualcomm Shared Memory Point to Point")
> Signed-off-by: Evan Green <evgreen@chromium.org>
> ---
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
next prev parent reply other threads:[~2020-10-16 16:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-29 20:30 [RESEND PATCH] soc: qcom: smp2p: Safely acquire spinlock without IRQs Evan Green
2020-10-16 16:48 ` Stephen Boyd [this message]
2020-10-16 17:13 ` Bjorn Andersson
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