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From:   "Michael Kelley (LINUX)" <mikelley@microsoft.com>
To:     "Andrea Parri (Microsoft)" <parri.andrea@gmail.com>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        Wei Hu <weh@microsoft.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Rob Herring <robh@kernel.org>,
        Krzysztof Wilczynski <kw@linux.com>,
        Bjorn Helgaas <bhelgaas@google.com>
CC:     "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 5/6] Drivers: hv: vmbus: Introduce
 {lock,unlock}_requestor()
Thread-Topic: [PATCH 5/6] Drivers: hv: vmbus: Introduce
 {lock,unlock}_requestor()
Thread-Index: AQHYSjh6DFUxGtO8e0m5GrS3S88ooKzmJXDg
Date:   Fri, 8 Apr 2022 15:28:37 +0000
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References: <20220407043028.379534-1-parri.andrea@gmail.com>
 <20220407043028.379534-6-parri.andrea@gmail.com>
In-Reply-To: <20220407043028.379534-6-parri.andrea@gmail.com>
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From: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Sent: Wednesday, Ap=
ril 6, 2022 9:30 PM
>=20
> To abtract the lock and unlock operations on the requestor spin lock.
> The helpers will come in handy in hv_pci.
>=20
> No functional change.
>=20
> Suggested-by: Michael Kelley <mikelley@microsoft.com>
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
> ---
>  drivers/hv/channel.c   | 11 +++++------
>  include/linux/hyperv.h | 15 +++++++++++++++
>  2 files changed, 20 insertions(+), 6 deletions(-)
>=20
> diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
> index 49f10a603a091..56f7e06c673e4 100644
> --- a/drivers/hv/channel.c
> +++ b/drivers/hv/channel.c
> @@ -1252,12 +1252,12 @@ u64 vmbus_next_request_id(struct vmbus_channel
> *channel, u64 rqst_addr)
>  	if (!channel->rqstor_size)
>  		return VMBUS_NO_RQSTOR;
>=20
> -	spin_lock_irqsave(&rqstor->req_lock, flags);
> +	lock_requestor(channel, flags);
>  	current_id =3D rqstor->next_request_id;
>=20
>  	/* Requestor array is full */
>  	if (current_id >=3D rqstor->size) {
> -		spin_unlock_irqrestore(&rqstor->req_lock, flags);
> +		unlock_requestor(channel, flags);
>  		return VMBUS_RQST_ERROR;
>  	}
>=20
> @@ -1267,7 +1267,7 @@ u64 vmbus_next_request_id(struct vmbus_channel
> *channel, u64 rqst_addr)
>  	/* The already held spin lock provides atomicity */
>  	bitmap_set(rqstor->req_bitmap, current_id, 1);
>=20
> -	spin_unlock_irqrestore(&rqstor->req_lock, flags);
> +	unlock_requestor(channel, flags);
>=20
>  	/*
>  	 * Cannot return an ID of 0, which is reserved for an unsolicited
> @@ -1327,13 +1327,12 @@ EXPORT_SYMBOL_GPL(__vmbus_request_addr_match);
>  u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id=
,
>  			     u64 rqst_addr)
>  {
> -	struct vmbus_requestor *rqstor =3D &channel->requestor;
>  	unsigned long flags;
>  	u64 req_addr;
>=20
> -	spin_lock_irqsave(&rqstor->req_lock, flags);
> +	lock_requestor(channel, flags);
>  	req_addr =3D __vmbus_request_addr_match(channel, trans_id, rqst_addr);
> -	spin_unlock_irqrestore(&rqstor->req_lock, flags);
> +	unlock_requestor(channel, flags);
>=20
>  	return req_addr;
>  }
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index c77d78f34b96a..015e4ceb43029 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1042,6 +1042,21 @@ struct vmbus_channel {
>  	u32 max_pkt_size;
>  };
>=20
> +#define lock_requestor(channel, flags)					\
> +do {									\
> +	struct vmbus_requestor *rqstor =3D &(channel)->requestor;		\
> +									\
> +	spin_lock_irqsave(&rqstor->req_lock, flags);			\
> +} while (0)
> +
> +static __always_inline void unlock_requestor(struct vmbus_channel *chann=
el,
> +					     unsigned long flags)
> +{
> +	struct vmbus_requestor *rqstor =3D &channel->requestor;
> +
> +	spin_unlock_irqrestore(&rqstor->req_lock, flags);
> +}
> +
>  u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr);
>  u64 __vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_=
id,
>  			       u64 rqst_addr);
> --
> 2.25.1

Reviewed-by: Michael Kelley <mikelley@microsoft.com>