evie/android_kernel_oneplus_msm8998
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Staging: hv: Introduce a function to wait to drain outgoing I/O

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Rather than busy loop waiting to drain I/O, introduce a function
that does not burn CPU cycles waiting.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Abhishek Kane <v-abkane@microsoft.com>
Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
K. Y. Srinivasan 2011-05-10 07:54:07 -07:00 • committed by Greg Kroah-Hartman
parent 43c51f7dd1
commit 604df37dc3
2 changed files with 17 additions and 1 deletions
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6
drivers/staging/hv/storvsc.c
View file

@ -47,6 +47,7 @@ static inline struct storvsc_device *alloc_stor_device(struct hv_device *device)
/* (ie get_stor_device() and must_get_stor_device()) to proceed. */
atomic_cmpxchg(&stor_device->ref_count, 0, 2);
init_waitqueue_head(&stor_device->waiting_to_drain);
stor_device->device = device;
device->ext = stor_device;
@ -332,7 +333,10 @@ static void stor_vsc_on_io_completion(struct hv_device *device,
request->on_io_completion(request);
atomic_dec(&stor_device->num_outstanding_req);
if (atomic_dec_and_test(&stor_device->num_outstanding_req) &&
stor_device->drain_notify)
wake_up(&stor_device->waiting_to_drain);
put_stor_device(device);
}

12
drivers/staging/hv/storvsc_api.h
View file

@ -26,6 +26,7 @@
#define _STORVSC_API_H_
#include <linux/kernel.h>
#include <linux/wait.h>
#include "vstorage.h"
#include "vmbus_api.h"
#include "vmbus.h"
@ -108,8 +109,11 @@ struct storvsc_device {
/* 0 indicates the device is being destroyed */
atomic_t ref_count;
bool drain_notify;
atomic_t num_outstanding_req;
wait_queue_head_t waiting_to_drain;
/*
* Each unique Port/Path/Target represents 1 channel ie scsi
* controller. In reality, the pathid, targetid is always 0
@ -161,6 +165,14 @@ struct storvsc_driver *drv_to_stordrv(struct device_driver *d)
return hvdr_to_stordr(hvdrv);
}
static inline void storvsc_wait_to_drain(struct storvsc_device *dev)
{
dev->drain_notify = true;
wait_event(dev->waiting_to_drain,
atomic_read(&dev->num_outstanding_req) == 0);
dev->drain_notify = false;
}
/* Interface */
int storvsc_dev_add(struct hv_device *device,