linux-kernel - RE: [PATCH 5/6] Drivers: hv: vmbus: Introduce {lock,unlock}

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Date:   Fri, 8 Apr 2022 15:28:37 +0000
From:   "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
To:     "Andrea Parri (Microsoft)" <parri.andrea@...il.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Wei Hu <weh@...rosoft.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczynski <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
CC:     "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 5/6] Drivers: hv: vmbus: Introduce
 {lock,unlock}_requestor()

From: Andrea Parri (Microsoft) <parri.andrea@...il.com> Sent: Wednesday, April 6, 2022 9:30 PM
> 
> To abtract the lock and unlock operations on the requestor spin lock.
> The helpers will come in handy in hv_pci.
> 
> No functional change.
> 
> Suggested-by: Michael Kelley <mikelley@...rosoft.com>
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@...il.com>
> ---
>  drivers/hv/channel.c   | 11 +++++------
>  include/linux/hyperv.h | 15 +++++++++++++++
>  2 files changed, 20 insertions(+), 6 deletions(-)
> 
> 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;
> 
> -	spin_lock_irqsave(&rqstor->req_lock, flags);
> +	lock_requestor(channel, flags);
>  	current_id = rqstor->next_request_id;
> 
>  	/* Requestor array is full */
>  	if (current_id >= rqstor->size) {
> -		spin_unlock_irqrestore(&rqstor->req_lock, flags);
> +		unlock_requestor(channel, flags);
>  		return VMBUS_RQST_ERROR;
>  	}
> 
> @@ -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);
> 
> -	spin_unlock_irqrestore(&rqstor->req_lock, flags);
> +	unlock_requestor(channel, flags);
> 
>  	/*
>  	 * 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 = &channel->requestor;
>  	unsigned long flags;
>  	u64 req_addr;
> 
> -	spin_lock_irqsave(&rqstor->req_lock, flags);
> +	lock_requestor(channel, flags);
>  	req_addr = __vmbus_request_addr_match(channel, trans_id, rqst_addr);
> -	spin_unlock_irqrestore(&rqstor->req_lock, flags);
> +	unlock_requestor(channel, flags);
> 
>  	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;
>  };
> 
> +#define lock_requestor(channel, flags)					\
> +do {									\
> +	struct vmbus_requestor *rqstor = &(channel)->requestor;		\
> +									\
> +	spin_lock_irqsave(&rqstor->req_lock, flags);			\
> +} while (0)
> +
> +static __always_inline void unlock_requestor(struct vmbus_channel *channel,
> +					     unsigned long flags)
> +{
> +	struct vmbus_requestor *rqstor = &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@...rosoft.com>