Re: [PATCH V2 10/12] Drivers: hv: vmbus: channge vmbus_connection.channel_lock to mutex

[Vitaly Kuznetsov]

"K. Y. Srinivasan" <kys@xxxxxxxxxxxxx> writes:

> From: Dexuan Cui <decui@xxxxxxxxxxxxx>
>
> spinlock is unnecessary here.
> mutex is enough.

Hm, mutex is usually required when we need to sleep and a spinlock is
enough otherwise :-)

Or are you trying to say we don't need to disable interrupts here? In
that can maybe we can just switch to spin_lock()/spin_unlock()?

>
> Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> ---
>  drivers/hv/channel_mgmt.c |   12 ++++++------
>  drivers/hv/connection.c   |    7 +++----
>  drivers/hv/hyperv_vmbus.h |    2 +-
>  3 files changed, 10 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
> index 9c9da3a..d013171 100644
> --- a/drivers/hv/channel_mgmt.c
> +++ b/drivers/hv/channel_mgmt.c
> @@ -206,9 +206,9 @@ void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid)
>  	}
>
>  	if (channel->primary_channel == NULL) {
> -		spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
> +		mutex_lock(&vmbus_connection.channel_mutex);
>  		list_del(&channel->listentry);
> -		spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
> +		mutex_unlock(&vmbus_connection.channel_mutex);
>
>  		primary_channel = channel;
>  	} else {
> @@ -253,7 +253,7 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
>  	unsigned long flags;
>
>  	/* Make sure this is a new offer */
> -	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
> +	mutex_lock(&vmbus_connection.channel_mutex);
>
>  	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
>  		if (!uuid_le_cmp(channel->offermsg.offer.if_type,
> @@ -269,7 +269,7 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
>  		list_add_tail(&newchannel->listentry,
>  			      &vmbus_connection.chn_list);
>
> -	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
> +	mutex_unlock(&vmbus_connection.channel_mutex);
>
>  	if (!fnew) {
>  		/*
> @@ -341,9 +341,9 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
>  err_deq_chan:
>  	vmbus_release_relid(newchannel->offermsg.child_relid);
>
> -	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
> +	mutex_lock(&vmbus_connection.channel_mutex);
>  	list_del(&newchannel->listentry);
> -	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
> +	mutex_unlock(&vmbus_connection.channel_mutex);
>
>  	if (newchannel->target_cpu != get_cpu()) {
>  		put_cpu();
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index 4fc2e88..521f48e 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -146,7 +146,7 @@ int vmbus_connect(void)
>  	spin_lock_init(&vmbus_connection.channelmsg_lock);
>
>  	INIT_LIST_HEAD(&vmbus_connection.chn_list);
> -	spin_lock_init(&vmbus_connection.channel_lock);
> +	mutex_init(&vmbus_connection.channel_mutex);
>
>  	/*
>  	 * Setup the vmbus event connection for channel interrupt
> @@ -282,11 +282,10 @@ struct vmbus_channel *relid2channel(u32 relid)
>  {
>  	struct vmbus_channel *channel;
>  	struct vmbus_channel *found_channel  = NULL;
> -	unsigned long flags;
>  	struct list_head *cur, *tmp;
>  	struct vmbus_channel *cur_sc;
>
> -	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
> +	mutex_lock(&vmbus_connection.channel_mutex);
>  	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
>  		if (channel->offermsg.child_relid == relid) {
>  			found_channel = channel;
> @@ -305,7 +304,7 @@ struct vmbus_channel *relid2channel(u32 relid)
>  			}
>  		}
>  	}
> -	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
> +	mutex_unlock(&vmbus_connection.channel_mutex);
>
>  	return found_channel;
>  }
> diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
> index 64950d8..0af6dce 100644
> --- a/drivers/hv/hyperv_vmbus.h
> +++ b/drivers/hv/hyperv_vmbus.h
> @@ -688,7 +688,7 @@ struct vmbus_connection {
>
>  	/* List of channels */
>  	struct list_head chn_list;
> -	spinlock_t channel_lock;
> +	struct mutex channel_mutex;
>
>  	struct workqueue_struct *work_queue;
>  };

-- 
  Vitaly
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