Commit 21d2052c authored by Andrea Parri (Microsoft)'s avatar Andrea Parri (Microsoft) Committed by Wei Liu
Browse files

scsi: storvsc: Introduce the per-storvsc_device spinlock 



storvsc uses the spinlock of the hv_device's primary channel to
serialize modifications of stor_chns[] performed by storvsc_do_io()
and storvsc_change_target_cpu(), when it could/should use a (per-)
storvsc_device spinlock: this change untangles the synchronization
mechanism for the (storvsc-specific) stor_chns[] array from the
"generic" VMBus code and data structures, clarifying the scope of
this synchronization mechanism.

Signed-off-by: default avatarAndrea Parri (Microsoft) <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20200617164642.37393-8-parri.andrea@gmail.com


Acked-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent 8a99e501

drivers/scsi/storvsc_drv.c

+11 −5
Original line number Diff line number Diff line
@@ -462,6 +462,11 @@ struct storvsc_device { 
	 * Mask of CPUs bound to subchannels.

	 */

	struct cpumask alloced_cpus;

	/*

	 * Serializes modifications of stor_chns[] from storvsc_do_io()

	 * and storvsc_change_target_cpu().

	 */

	spinlock_t lock;

	/* Used for vsc/vsp channel reset process */

	struct storvsc_cmd_request init_request;

	struct storvsc_cmd_request reset_request;
@@ -639,7 +644,7 @@ static void storvsc_change_target_cpu(struct vmbus_channel *channel, u32 old, 
		return;



	/* See storvsc_do_io() -> get_og_chn(). */

	spin_lock_irqsave(&device->channel->lock, flags);

	spin_lock_irqsave(&stor_device->lock, flags);



	/*

	 * Determines if the storvsc device has other channels assigned to
@@ -676,7 +681,7 @@ old_is_alloced: 
	WRITE_ONCE(stor_device->stor_chns[new], channel);

	cpumask_set_cpu(new, &stor_device->alloced_cpus);



	spin_unlock_irqrestore(&device->channel->lock, flags);

	spin_unlock_irqrestore(&stor_device->lock, flags);

}



static void handle_sc_creation(struct vmbus_channel *new_sc)
@@ -1433,14 +1438,14 @@ static int storvsc_do_io(struct hv_device *device, 
			}

		}

	} else {

		spin_lock_irqsave(&device->channel->lock, flags);

		spin_lock_irqsave(&stor_device->lock, flags);

		outgoing_channel = stor_device->stor_chns[q_num];

		if (outgoing_channel != NULL) {

			spin_unlock_irqrestore(&device->channel->lock, flags);

			spin_unlock_irqrestore(&stor_device->lock, flags);

			goto found_channel;

		}

		outgoing_channel = get_og_chn(stor_device, q_num);

		spin_unlock_irqrestore(&device->channel->lock, flags);

		spin_unlock_irqrestore(&stor_device->lock, flags);

	}



found_channel:
@@ -1881,6 +1886,7 @@ static int storvsc_probe(struct hv_device *device, 
	init_waitqueue_head(&stor_device->waiting_to_drain);

	stor_device->device = device;

	stor_device->host = host;

	spin_lock_init(&stor_device->lock);

	hv_set_drvdata(device, stor_device);



	stor_device->port_number = host->host_no;

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