linux-kernel - Re: [PATCH v16 07/34] gunyah: rsc_mgr: Add resource manager RPC core

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Date: Wed, 10 Jan 2024 09:48:16 -0800
From: Elliot Berman <quic_eberman@...cinc.com>
To: Hillf Danton <hdanton@...a.com>
CC: Will Deacon <will@...nel.org>, Sean Christopherson <seanjc@...gle.com>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v16 07/34] gunyah: rsc_mgr: Add resource manager RPC core



On 1/10/2024 3:41 AM, Hillf Danton wrote:
> On Tue, 9 Jan 2024 11:37:45 -0800 Elliot Berman <quic_eberman@...cinc.com>
>> +
>> +static irqreturn_t gunyah_rm_tx(int irq, void *data)
>> +{
>> +	struct gunyah_rm *rm = data;
>> +
>> +	complete_all(&rm->send_ready);
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static int gunyah_rm_msgq_send(struct gunyah_rm *rm, size_t size, bool push)
>> +	__must_hold(&rm->send_lock)
>> +{
>> +	const u64 tx_flags = push ? GUNYAH_HYPERCALL_MSGQ_TX_FLAGS_PUSH : 0;
>> +	enum gunyah_error gunyah_error;
>> +	void *data = &rm->send_msg[0];
>> +	bool ready;
> 
> 	lockdep_assert_held(&rm->send_lock); instead of __must_hold
>> +
>> +again:
>> +	wait_for_completion(&rm->send_ready);
>> +	/* reinit completion before hypercall. As soon as hypercall returns, we could get the
>> +	 * ready interrupt. This might be before we have time to reinit the completion
>> +	 */
>> +	reinit_completion(&rm->send_ready);
> 
> Given wait_for_completion(&rm->send_ready) with rm->send_lock held,
> complete(&rm->send_ready) works for you with the bonus of cutting this
> reinit off.
> 

Good point, thanks! Applied both suggestions

- Elliot