[RFC PATCH v2 11/22] devlink: add functions to take snapshot while locked

Jacob Keller
2020-02-14T23:22:34Z

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_id_get and devlink_region_snapshot_create
functions while already holding the devlink instance lock.

Extract the logic of these two functions into static functions prefixed
by `__` to indicate they are internal helper functions. Modify the
original functions to be implemented in terms of the new locked
functions.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
---
net/core/devlink.c | 93 ++++++++++++++++++++++++++++++----------------
1 file changed, 61 insertions(+), 32 deletions(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index fef93f48028c..0e94887713f4 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -3760,6 +3760,65 @@ static void devlink_nl_region_notify(struct devlink_region *region,
nlmsg_free(msg);
}

+/**
+ * __devlink_region_snapshot_id_get - get snapshot ID
+ * @devlink: devlink instance
+ *
+ * Returns a new snapshot id. Must be called while holding the
+ * devlink instance lock.
+ */
+static u32 __devlink_region_snapshot_id_get(struct devlink *devlink)
+{
+ lockdep_assert_held(&devlink->lock);
+ return ++devlink->snapshot_id;
+}
+
+/**
+ * __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)
{
@@ -7618,7 +7677,7 @@ u32 devlink_region_snapshot_id_get(struct devlink *devlink)
u32 id;

mutex_lock(&devlink->lock);
- id = ++devlink->snapshot_id;
+ id = __devlink_region_snapshot_id_get(devlink);
mutex_unlock(&devlink->lock);

return id;
@@ -7641,42 +7700,12 @@ 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);
--
2.25.0.368.g28a2d05eebfb