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scsi: storvsc: Introduce the per-storvsc_device spinlock

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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: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20200617164642.37393-8-parri.andrea@gmail.com
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Andrea Parri (Microsoft) 2020-06-17 18:46:41 +02:00 committed by Wei Liu
parent 8a99e50134
commit 21d2052c7a
1 changed files with 11 additions and 5 deletions
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16
drivers/scsi/storvsc_drv.c
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@ -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;