Commit a6a51adc authored by Eli Cohen's avatar Eli Cohen Committed by Michael S. Tsirkin
Browse files

net/vdpa: Use readers/writers semaphore instead of cf_mutex 



Replace cf_mutex with rw_semaphore to reflect the fact that some calls
could be called concurrently but can suffice with read lock.

Suggested-by: default avatarSi-Wei Liu <si-wei.liu@oracle.com>
Signed-off-by: default avatarEli Cohen <elic@nvidia.com>
Message-Id: <20220518133804.1075129-5-elic@nvidia.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 0078ad90

drivers/vdpa/vdpa.c

+12 −13
Original line number Diff line number Diff line
@@ -23,9 +23,9 @@ static DEFINE_IDA(vdpa_index_ida); 


void vdpa_set_status(struct vdpa_device *vdev, u8 status)

{

	mutex_lock(&vdev->cf_mutex);

	down_write(&vdev->cf_lock);

	vdev->config->set_status(vdev, status);

	mutex_unlock(&vdev->cf_mutex);

	up_write(&vdev->cf_lock);

}

EXPORT_SYMBOL(vdpa_set_status);
@@ -148,7 +148,6 @@ static void vdpa_release_dev(struct device *d) 
		ops->free(vdev);



	ida_simple_remove(&vdpa_index_ida, vdev->index);

	mutex_destroy(&vdev->cf_mutex);

	kfree(vdev->driver_override);

	kfree(vdev);

}
@@ -211,7 +210,7 @@ struct vdpa_device *__vdpa_alloc_device(struct device *parent, 
	if (err)

		goto err_name;



	mutex_init(&vdev->cf_mutex);

	init_rwsem(&vdev->cf_lock);

	device_initialize(&vdev->dev);



	return vdev;
@@ -407,9 +406,9 @@ static void vdpa_get_config_unlocked(struct vdpa_device *vdev, 
void vdpa_get_config(struct vdpa_device *vdev, unsigned int offset,

		     void *buf, unsigned int len)

{

	mutex_lock(&vdev->cf_mutex);

	down_read(&vdev->cf_lock);

	vdpa_get_config_unlocked(vdev, offset, buf, len);

	mutex_unlock(&vdev->cf_mutex);

	up_read(&vdev->cf_lock);

}

EXPORT_SYMBOL_GPL(vdpa_get_config);
@@ -423,9 +422,9 @@ EXPORT_SYMBOL_GPL(vdpa_get_config); 
void vdpa_set_config(struct vdpa_device *vdev, unsigned int offset,

		     const void *buf, unsigned int length)

{

	mutex_lock(&vdev->cf_mutex);

	down_write(&vdev->cf_lock);

	vdev->config->set_config(vdev, offset, buf, length);

	mutex_unlock(&vdev->cf_mutex);

	up_write(&vdev->cf_lock);

}

EXPORT_SYMBOL_GPL(vdpa_set_config);
@@ -866,7 +865,7 @@ vdpa_dev_config_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, 
	u8 status;

	int err;



	mutex_lock(&vdev->cf_mutex);

	down_read(&vdev->cf_lock);

	status = vdev->config->get_status(vdev);

	if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {

		NL_SET_ERR_MSG_MOD(extack, "Features negotiation not completed");
@@ -903,14 +902,14 @@ vdpa_dev_config_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, 
	if (err)

		goto msg_err;



	mutex_unlock(&vdev->cf_mutex);

	up_read(&vdev->cf_lock);

	genlmsg_end(msg, hdr);

	return 0;



msg_err:

	genlmsg_cancel(msg, hdr);

out:

	mutex_unlock(&vdev->cf_mutex);

	up_read(&vdev->cf_lock);

	return err;

}
@@ -954,7 +953,7 @@ static int vendor_stats_fill(struct vdpa_device *vdev, struct sk_buff *msg, 
{

	int err;



	mutex_lock(&vdev->cf_mutex);

	down_read(&vdev->cf_lock);

	if (!vdev->config->get_vendor_vq_stats) {

		err = -EOPNOTSUPP;

		goto out;
@@ -962,7 +961,7 @@ static int vendor_stats_fill(struct vdpa_device *vdev, struct sk_buff *msg, 


	err = vdpa_fill_stats_rec(vdev, msg, info, index);

out:

	mutex_unlock(&vdev->cf_mutex);

	up_read(&vdev->cf_lock);

	return err;

}

include/linux/vdpa.h

+6 −6
Original line number Diff line number Diff line
@@ -66,7 +66,7 @@ struct vdpa_mgmt_dev; 
 * @dma_dev: the actual device that is performing DMA

 * @driver_override: driver name to force a match

 * @config: the configuration ops for this device.

 * @cf_mutex: Protects get and set access to configuration layout.

 * @cf_lock: Protects get and set access to configuration layout.

 * @index: device index

 * @features_valid: were features initialized? for legacy guests

 * @use_va: indicate whether virtual address must be used by this device
@@ -79,7 +79,7 @@ struct vdpa_device { 
	struct device *dma_dev;

	const char *driver_override;

	const struct vdpa_config_ops *config;

	struct mutex cf_mutex; /* Protects get/set config */

	struct rw_semaphore cf_lock; /* Protects get/set config */

	unsigned int index;

	bool features_valid;

	bool use_va;
@@ -398,10 +398,10 @@ static inline int vdpa_reset(struct vdpa_device *vdev) 
	const struct vdpa_config_ops *ops = vdev->config;

	int ret;



	mutex_lock(&vdev->cf_mutex);

	down_write(&vdev->cf_lock);

	vdev->features_valid = false;

	ret = ops->reset(vdev);

	mutex_unlock(&vdev->cf_mutex);

	up_write(&vdev->cf_lock);

	return ret;

}
@@ -420,9 +420,9 @@ static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features) 
{

	int ret;



	mutex_lock(&vdev->cf_mutex);

	down_write(&vdev->cf_lock);

	ret = vdpa_set_features_unlocked(vdev, features);

	mutex_unlock(&vdev->cf_mutex);

	up_write(&vdev->cf_lock);



	return ret;

}