linux-kernel - Re: [PATCH 3/7] hwspinlock: Introduce hwspin_lock

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Date: Fri, 17 May 2024 10:47:08 +0200
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Chris Lew <quic_clew@...cinc.com>, Bjorn Andersson
 <andersson@...nel.org>, Baolin Wang <baolin.wang@...ux.alibaba.com>,
 Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Will Deacon <will@...nel.org>, Waiman Long <longman@...hat.com>,
 Boqun Feng <boqun.feng@...il.com>, Jonathan Corbet <corbet@....net>,
 Mathieu Poirier <mathieu.poirier@...aro.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>,
 Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
 Konrad Dybcio <konrad.dybcio@...aro.org>
Cc: linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-doc@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 devicetree@...r.kernel.org, Richard Maina <quic_rmaina@...cinc.com>
Subject: Re: [PATCH 3/7] hwspinlock: Introduce hwspin_lock_bust()

On 17/05/2024 10:07, Bryan O'Donoghue wrote:
> On 17/05/2024 00:58, Chris Lew wrote:
>> From: Richard Maina <quic_rmaina@...cinc.com>
>>
>> When a remoteproc crashes or goes down unexpectedly this can result in
>> a state where locks held by the remoteproc will remain locked possibly
>> resulting in deadlock. This new API hwspin_lock_bust() allows
>> hwspinlock implementers to define a bust operation for freeing previously
>> acquired hwspinlocks after verifying ownership of the acquired lock.
>>
>> Signed-off-by: Richard Maina <quic_rmaina@...cinc.com>
>> Signed-off-by: Chris Lew <quic_clew@...cinc.com>
>> ---
>>   Documentation/locking/hwspinlock.rst     | 11 +++++++++++
>>   drivers/hwspinlock/hwspinlock_core.c     | 30 
>> +++++++++++++++++++++++++++++-
> 
> Shouldn't this be added to drivers/hwspinlock/qcom_hwspinlock.c ?
> 
>>   drivers/hwspinlock/hwspinlock_internal.h |  3 +++
>>   include/linux/hwspinlock.h               |  6 ++++++
>>   4 files changed, 49 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/locking/hwspinlock.rst 
>> b/Documentation/locking/hwspinlock.rst
>> index c1c2c827b575..6ee94cc6d3b7 100644
>> --- a/Documentation/locking/hwspinlock.rst
>> +++ b/Documentation/locking/hwspinlock.rst
>> @@ -85,6 +85,17 @@ is already free).
>>   Should be called from a process context (might sleep).
>> +::
>> +
>> +  int hwspin_lock_bust(struct hwspinlock *hwlock, unsigned int id);
> 
> I don't think this is a geat name "bust" looks alot like "burst" and I 
> don't think aligns well with the established namespace.
> 
> Why not simply qcom_hwspinlock_unlock_force() - which is what you are 
> doing - forcing the hw spinlock to unlock.

hmm looking again, I think _core is the right place and bust() is 
consistent with bust_spinlocks();

meh

---
bod