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devlink: add function to take snapshot while locked
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A future change is going to add a new devlink command to request
a snapshot on demand. This function will want to call the
devlink_region_snapshot_create function while already holding the
devlink instance lock.

Extract the logic of this function into a static function prefixed by
`__` to indicate that it is an internal helper function. Modify the
original function to be implemented in terms of the new locked
function.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Jacob Keller authored and David S. Miller committed Mar 27, 2020
1 parent 6d82f67 commit cf80fae
Showing 1 changed file with 47 additions and 31 deletions.
78 changes: 47 additions & 31 deletions net/core/devlink.c
Original file line number Diff line number Diff line change
Expand Up @@ -3768,6 +3768,52 @@ static void devlink_nl_region_notify(struct devlink_region *region,
nlmsg_free(msg);
}

/**
* __devlink_region_snapshot_create - create a new snapshot
* This will add a new snapshot of a region. The snapshot
* will be stored on the region struct and can be accessed
* from devlink. This is useful for future analyses of snapshots.
* Multiple snapshots can be created on a region.
* The @snapshot_id should be obtained using the getter function.
*
* Must be called only while holding the devlink instance lock.
*
* @region: devlink region of the snapshot
* @data: snapshot data
* @snapshot_id: snapshot id to be created
*/
static int
__devlink_region_snapshot_create(struct devlink_region *region,
u8 *data, u32 snapshot_id)
{
struct devlink *devlink = region->devlink;
struct devlink_snapshot *snapshot;

lockdep_assert_held(&devlink->lock);

/* check if region can hold one more snapshot */
if (region->cur_snapshots == region->max_snapshots)
return -ENOMEM;

if (devlink_region_snapshot_get_by_id(region, snapshot_id))
return -EEXIST;

snapshot = kzalloc(sizeof(*snapshot), GFP_KERNEL);
if (!snapshot)
return -ENOMEM;

snapshot->id = snapshot_id;
snapshot->region = region;
snapshot->data = data;

list_add_tail(&snapshot->list, &region->snapshot_list);

region->cur_snapshots++;

devlink_nl_region_notify(region, snapshot, DEVLINK_CMD_REGION_NEW);
return 0;
}

static void devlink_region_snapshot_del(struct devlink_region *region,
struct devlink_snapshot *snapshot)
{
Expand Down Expand Up @@ -7753,42 +7799,12 @@ int devlink_region_snapshot_create(struct devlink_region *region,
u8 *data, u32 snapshot_id)
{
struct devlink *devlink = region->devlink;
struct devlink_snapshot *snapshot;
int err;

mutex_lock(&devlink->lock);

/* check if region can hold one more snapshot */
if (region->cur_snapshots == region->max_snapshots) {
err = -ENOMEM;
goto unlock;
}

if (devlink_region_snapshot_get_by_id(region, snapshot_id)) {
err = -EEXIST;
goto unlock;
}

snapshot = kzalloc(sizeof(*snapshot), GFP_KERNEL);
if (!snapshot) {
err = -ENOMEM;
goto unlock;
}

snapshot->id = snapshot_id;
snapshot->region = region;
snapshot->data = data;

list_add_tail(&snapshot->list, &region->snapshot_list);

region->cur_snapshots++;

devlink_nl_region_notify(region, snapshot, DEVLINK_CMD_REGION_NEW);
err = __devlink_region_snapshot_create(region, data, snapshot_id);
mutex_unlock(&devlink->lock);
return 0;

unlock:
mutex_unlock(&devlink->lock);
return err;
}
EXPORT_SYMBOL_GPL(devlink_region_snapshot_create);
Expand Down

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