[RFC PATCH v2 12/22] devlink: convert snapshot id getter to return an error

Jacob Keller
2020-02-14T23:23:11Z

Modify the devlink_snapshot_id_get function to return a signed value,
enabling reporting an error on failure.

This enables easily refactoring how IDs are generated and kept track of
in the future. For now, just report ENOSPC once INT_MAX snapshot ids
have been returned.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
---
drivers/net/ethernet/mellanox/mlx4/crdump.c | 10 +++++++---
drivers/net/netdevsim/dev.c | 7 +++++--
include/net/devlink.h | 2 +-
net/core/devlink.c | 16 +++++++++++-----
4 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/crdump.c b/drivers/net/ethernet/mellanox/mlx4/crdump.c
index c3f90c0f9554..723a66efdf32 100644
--- a/drivers/net/ethernet/mellanox/mlx4/crdump.c
+++ b/drivers/net/ethernet/mellanox/mlx4/crdump.c
@@ -169,7 +169,7 @@ int mlx4_crdump_collect(struct mlx4_dev *dev)
struct pci_dev *pdev = dev->persist->pdev;
unsigned long cr_res_size;
u8 __iomem *cr_space;
- u32 id;
+ int id;

if (!dev->caps.health_buffer_addrs) {
mlx4_info(dev, "crdump: FW doesn't support health buffer access, skipping\n");
@@ -189,10 +189,14 @@ int mlx4_crdump_collect(struct mlx4_dev *dev)
return -ENODEV;
}

- crdump_enable_crspace_access(dev, cr_space);
-
/* Get the available snapshot ID for the dumps */
id = devlink_region_snapshot_id_get(devlink);
+ if (id < 0) {
+ mlx4_err(dev, "crdump: devlink get snapshot id err %d\n", id);
+ return id;
+ }
+
+ crdump_enable_crspace_access(dev, cr_space);

/* Try to capture dumps */
mlx4_crdump_collect_crspace(dev, cr_space, id);
diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
index 5b1ba67fd4a0..e30bd94c3d52 100644
--- a/drivers/net/netdevsim/dev.c
+++ b/drivers/net/netdevsim/dev.c
@@ -44,8 +44,7 @@ static ssize_t nsim_dev_take_snapshot_write(struct file *file,
{
struct nsim_dev *nsim_dev = file->private_data;
void *dummy_data;
- int err;
- u32 id;
+ int err, id;

dummy_data = kmalloc(NSIM_DEV_DUMMY_REGION_SIZE, GFP_KERNEL);
if (!dummy_data)
@@ -54,6 +53,10 @@ static ssize_t nsim_dev_take_snapshot_write(struct file *file,
get_random_bytes(dummy_data, NSIM_DEV_DUMMY_REGION_SIZE);

id = devlink_region_snapshot_id_get(priv_to_devlink(nsim_dev));
+ if (id < 0) {
+ pr_err("Failed to get snapshot id\n");
+ return id;
+ }
err = devlink_region_snapshot_create(nsim_dev->dummy_region,
dummy_data, id);
if (err) {
diff --git a/include/net/devlink.h b/include/net/devlink.h
index 437d3f51a5ab..3a7759355434 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -962,7 +962,7 @@ devlink_region_create(struct devlink *devlink,
const struct devlink_region_ops *ops,
u32 region_max_snapshots, u64 region_size);
void devlink_region_destroy(struct devlink_region *region);
-u32 devlink_region_snapshot_id_get(struct devlink *devlink);
+int devlink_region_snapshot_id_get(struct devlink *devlink);
int devlink_region_snapshot_create(struct devlink_region *region,
u8 *data, u32 snapshot_id);
int devlink_info_serial_number_put(struct devlink_info_req *req,
diff --git a/net/core/devlink.c b/net/core/devlink.c
index 0e94887713f4..da4e669f425b 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -3764,12 +3764,16 @@ static void devlink_nl_region_notify(struct devlink_region *region,
* __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.
+ * Returns a new snapshot id or a negative error code on failure. Must be
+ * called while holding the devlink instance lock.
*/
-static u32 __devlink_region_snapshot_id_get(struct devlink *devlink)
+static int __devlink_region_snapshot_id_get(struct devlink *devlink)
{
lockdep_assert_held(&devlink->lock);
+
+ if (devlink->snapshot_id >= INT_MAX)
+ return -ENOSPC;
+
return ++devlink->snapshot_id;
}

@@ -7670,11 +7674,13 @@ EXPORT_SYMBOL_GPL(devlink_region_destroy);
* Driver should use the same id for multiple snapshots taken
* on multiple regions at the same time/by the same trigger.
*
+ * Returns a positive id or a negative error code on failure.
+ *
* @devlink: devlink
*/
-u32 devlink_region_snapshot_id_get(struct devlink *devlink)
+int devlink_region_snapshot_id_get(struct devlink *devlink)
{
- u32 id;
+ int id;

mutex_lock(&devlink->lock);
id = __devlink_region_snapshot_id_get(devlink);
--
2.25.0.368.g28a2d05eebfb