[ammarfaizi2-block:netdev/net-next/main 20/29] net/core/devlink.c:6392 devlink_nl_cmd_region_new() warn: inconsistent returns '&region->snapshot_lock'.

From: Dan Carpenter
Date: Mon Aug 01 2022 - 07:31:31 EST

tree: https://github.com/ammarfaizi2/linux-block netdev/net-next/main
head: 63757225a93353bc2ce4499af5501eabdbbf23f9
commit: 2dec18ad826f52658f7781ee995d236cc449b678 [20/29] net: devlink: remove region snapshots list dependency on devlink->lock
config: arc-randconfig-m041-20220731 (https://download.01.org/0day-ci/archive/20220731/202207311503.QBFSGqiL-lkp@xxxxxxxxx/config)
compiler: arceb-elf-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

New smatch warnings:
net/core/devlink.c:6392 devlink_nl_cmd_region_new() warn: inconsistent returns '&region->snapshot_lock'.

Old smatch warnings:
net/core/devlink.c:7284 devlink_fmsg_prepare_skb() error: uninitialized symbol 'err'.
arch/arc/include/asm/thread_info.h:62 current_thread_info() error: uninitialized symbol 'sp'.

vim +6392 net/core/devlink.c

b9a17abfde842b Jacob Keller 2020-03-26 6271 static int
b9a17abfde842b Jacob Keller 2020-03-26 6272 devlink_nl_cmd_region_new(struct sk_buff *skb, struct genl_info *info)
b9a17abfde842b Jacob Keller 2020-03-26 6273 {
b9a17abfde842b Jacob Keller 2020-03-26 6274 struct devlink *devlink = info->user_ptr[0];
043b3e22768d5d Jakub Kicinski 2020-05-01 6275 struct devlink_snapshot *snapshot;
544e7c33ec2f80 Andrew Lunn 2020-10-04 6276 struct devlink_port *port = NULL;
043b3e22768d5d Jakub Kicinski 2020-05-01 6277 struct nlattr *snapshot_id_attr;
b9a17abfde842b Jacob Keller 2020-03-26 6278 struct devlink_region *region;
b9a17abfde842b Jacob Keller 2020-03-26 6279 const char *region_name;
544e7c33ec2f80 Andrew Lunn 2020-10-04 6280 unsigned int index;
b9a17abfde842b Jacob Keller 2020-03-26 6281 u32 snapshot_id;
b9a17abfde842b Jacob Keller 2020-03-26 6282 u8 *data;
b9a17abfde842b Jacob Keller 2020-03-26 6283 int err;
b9a17abfde842b Jacob Keller 2020-03-26 6284
b9a17abfde842b Jacob Keller 2020-03-26 6285 if (!info->attrs[DEVLINK_ATTR_REGION_NAME]) {
b9a17abfde842b Jacob Keller 2020-03-26 6286 NL_SET_ERR_MSG_MOD(info->extack, "No region name provided");
b9a17abfde842b Jacob Keller 2020-03-26 6287 return -EINVAL;
b9a17abfde842b Jacob Keller 2020-03-26 6288 }
b9a17abfde842b Jacob Keller 2020-03-26 6289
b9a17abfde842b Jacob Keller 2020-03-26 6290 region_name = nla_data(info->attrs[DEVLINK_ATTR_REGION_NAME]);
544e7c33ec2f80 Andrew Lunn 2020-10-04 6291
544e7c33ec2f80 Andrew Lunn 2020-10-04 6292 if (info->attrs[DEVLINK_ATTR_PORT_INDEX]) {
544e7c33ec2f80 Andrew Lunn 2020-10-04 6293 index = nla_get_u32(info->attrs[DEVLINK_ATTR_PORT_INDEX]);
544e7c33ec2f80 Andrew Lunn 2020-10-04 6294
544e7c33ec2f80 Andrew Lunn 2020-10-04 6295 port = devlink_port_get_by_index(devlink, index);
544e7c33ec2f80 Andrew Lunn 2020-10-04 6296 if (!port)
544e7c33ec2f80 Andrew Lunn 2020-10-04 6297 return -ENODEV;
544e7c33ec2f80 Andrew Lunn 2020-10-04 6298 }
544e7c33ec2f80 Andrew Lunn 2020-10-04 6299
544e7c33ec2f80 Andrew Lunn 2020-10-04 6300 if (port)
544e7c33ec2f80 Andrew Lunn 2020-10-04 6301 region = devlink_port_region_get_by_name(port, region_name);
544e7c33ec2f80 Andrew Lunn 2020-10-04 6302 else
b9a17abfde842b Jacob Keller 2020-03-26 6303 region = devlink_region_get_by_name(devlink, region_name);
544e7c33ec2f80 Andrew Lunn 2020-10-04 6304
b9a17abfde842b Jacob Keller 2020-03-26 6305 if (!region) {
b9a17abfde842b Jacob Keller 2020-03-26 6306 NL_SET_ERR_MSG_MOD(info->extack, "The requested region does not exist");
b9a17abfde842b Jacob Keller 2020-03-26 6307 return -EINVAL;
b9a17abfde842b Jacob Keller 2020-03-26 6308 }
b9a17abfde842b Jacob Keller 2020-03-26 6309
b9a17abfde842b Jacob Keller 2020-03-26 6310 if (!region->ops->snapshot) {
b9a17abfde842b Jacob Keller 2020-03-26 6311 NL_SET_ERR_MSG_MOD(info->extack, "The requested region does not support taking an immediate snapshot");
b9a17abfde842b Jacob Keller 2020-03-26 6312 return -EOPNOTSUPP;
b9a17abfde842b Jacob Keller 2020-03-26 6313 }
b9a17abfde842b Jacob Keller 2020-03-26 6314
2dec18ad826f52 Jiri Pirko 2022-07-28 6315 mutex_lock(&region->snapshot_lock);

New locking

2dec18ad826f52 Jiri Pirko 2022-07-28 6316
b9a17abfde842b Jacob Keller 2020-03-26 6317 if (region->cur_snapshots == region->max_snapshots) {
b9a17abfde842b Jacob Keller 2020-03-26 6318 NL_SET_ERR_MSG_MOD(info->extack, "The region has reached the maximum number of stored snapshots");
2dec18ad826f52 Jiri Pirko 2022-07-28 6319 err = -ENOSPC;
2dec18ad826f52 Jiri Pirko 2022-07-28 6320 goto unlock;
b9a17abfde842b Jacob Keller 2020-03-26 6321 }
b9a17abfde842b Jacob Keller 2020-03-26 6322
043b3e22768d5d Jakub Kicinski 2020-05-01 6323 snapshot_id_attr = info->attrs[DEVLINK_ATTR_REGION_SNAPSHOT_ID];
043b3e22768d5d Jakub Kicinski 2020-05-01 6324 if (snapshot_id_attr) {
043b3e22768d5d Jakub Kicinski 2020-05-01 6325 snapshot_id = nla_get_u32(snapshot_id_attr);
b9a17abfde842b Jacob Keller 2020-03-26 6326
b9a17abfde842b Jacob Keller 2020-03-26 6327 if (devlink_region_snapshot_get_by_id(region, snapshot_id)) {
b9a17abfde842b Jacob Keller 2020-03-26 6328 NL_SET_ERR_MSG_MOD(info->extack, "The requested snapshot id is already in use");
2dec18ad826f52 Jiri Pirko 2022-07-28 6329 err = -EEXIST;
2dec18ad826f52 Jiri Pirko 2022-07-28 6330 goto unlock;
b9a17abfde842b Jacob Keller 2020-03-26 6331 }
b9a17abfde842b Jacob Keller 2020-03-26 6332
b9a17abfde842b Jacob Keller 2020-03-26 6333 err = __devlink_snapshot_id_insert(devlink, snapshot_id);
b9a17abfde842b Jacob Keller 2020-03-26 6334 if (err)
2dec18ad826f52 Jiri Pirko 2022-07-28 6335 goto unlock;
043b3e22768d5d Jakub Kicinski 2020-05-01 6336 } else {
043b3e22768d5d Jakub Kicinski 2020-05-01 6337 err = __devlink_region_snapshot_id_get(devlink, &snapshot_id);
043b3e22768d5d Jakub Kicinski 2020-05-01 6338 if (err) {
043b3e22768d5d Jakub Kicinski 2020-05-01 6339 NL_SET_ERR_MSG_MOD(info->extack, "Failed to allocate a new snapshot id");
2dec18ad826f52 Jiri Pirko 2022-07-28 6340 goto unlock;
043b3e22768d5d Jakub Kicinski 2020-05-01 6341 }
043b3e22768d5d Jakub Kicinski 2020-05-01 6342 }
b9a17abfde842b Jacob Keller 2020-03-26 6343
544e7c33ec2f80 Andrew Lunn 2020-10-04 6344 if (port)
544e7c33ec2f80 Andrew Lunn 2020-10-04 6345 err = region->port_ops->snapshot(port, region->port_ops,
544e7c33ec2f80 Andrew Lunn 2020-10-04 6346 info->extack, &data);
544e7c33ec2f80 Andrew Lunn 2020-10-04 6347 else
544e7c33ec2f80 Andrew Lunn 2020-10-04 6348 err = region->ops->snapshot(devlink, region->ops,
544e7c33ec2f80 Andrew Lunn 2020-10-04 6349 info->extack, &data);
b9a17abfde842b Jacob Keller 2020-03-26 6350 if (err)
b9a17abfde842b Jacob Keller 2020-03-26 6351 goto err_snapshot_capture;
b9a17abfde842b Jacob Keller 2020-03-26 6352
b9a17abfde842b Jacob Keller 2020-03-26 6353 err = __devlink_region_snapshot_create(region, data, snapshot_id);
b9a17abfde842b Jacob Keller 2020-03-26 6354 if (err)
b9a17abfde842b Jacob Keller 2020-03-26 6355 goto err_snapshot_create;
b9a17abfde842b Jacob Keller 2020-03-26 6356
043b3e22768d5d Jakub Kicinski 2020-05-01 6357 if (!snapshot_id_attr) {
043b3e22768d5d Jakub Kicinski 2020-05-01 6358 struct sk_buff *msg;
043b3e22768d5d Jakub Kicinski 2020-05-01 6359
043b3e22768d5d Jakub Kicinski 2020-05-01 6360 snapshot = devlink_region_snapshot_get_by_id(region,
043b3e22768d5d Jakub Kicinski 2020-05-01 6361 snapshot_id);
043b3e22768d5d Jakub Kicinski 2020-05-01 6362 if (WARN_ON(!snapshot))
043b3e22768d5d Jakub Kicinski 2020-05-01 6363 return -EINVAL;

unlock before returning?

043b3e22768d5d Jakub Kicinski 2020-05-01 6364
043b3e22768d5d Jakub Kicinski 2020-05-01 6365 msg = devlink_nl_region_notify_build(region, snapshot,
043b3e22768d5d Jakub Kicinski 2020-05-01 6366 DEVLINK_CMD_REGION_NEW,
043b3e22768d5d Jakub Kicinski 2020-05-01 6367 info->snd_portid,
043b3e22768d5d Jakub Kicinski 2020-05-01 6368 info->snd_seq);
043b3e22768d5d Jakub Kicinski 2020-05-01 6369 err = PTR_ERR_OR_ZERO(msg);
043b3e22768d5d Jakub Kicinski 2020-05-01 6370 if (err)
043b3e22768d5d Jakub Kicinski 2020-05-01 6371 goto err_notify;
043b3e22768d5d Jakub Kicinski 2020-05-01 6372
043b3e22768d5d Jakub Kicinski 2020-05-01 6373 err = genlmsg_reply(msg, info);
043b3e22768d5d Jakub Kicinski 2020-05-01 6374 if (err)
043b3e22768d5d Jakub Kicinski 2020-05-01 6375 goto err_notify;
043b3e22768d5d Jakub Kicinski 2020-05-01 6376 }
043b3e22768d5d Jakub Kicinski 2020-05-01 6377
2dec18ad826f52 Jiri Pirko 2022-07-28 6378 mutex_unlock(&region->snapshot_lock);
b9a17abfde842b Jacob Keller 2020-03-26 6379 return 0;
b9a17abfde842b Jacob Keller 2020-03-26 6380
b9a17abfde842b Jacob Keller 2020-03-26 6381 err_snapshot_create:
b9a17abfde842b Jacob Keller 2020-03-26 6382 region->ops->destructor(data);
b9a17abfde842b Jacob Keller 2020-03-26 6383 err_snapshot_capture:
b9a17abfde842b Jacob Keller 2020-03-26 6384 __devlink_snapshot_id_decrement(devlink, snapshot_id);
2dec18ad826f52 Jiri Pirko 2022-07-28 6385 mutex_unlock(&region->snapshot_lock);
b9a17abfde842b Jacob Keller 2020-03-26 6386 return err;
043b3e22768d5d Jakub Kicinski 2020-05-01 6387
043b3e22768d5d Jakub Kicinski 2020-05-01 6388 err_notify:
043b3e22768d5d Jakub Kicinski 2020-05-01 6389 devlink_region_snapshot_del(region, snapshot);
2dec18ad826f52 Jiri Pirko 2022-07-28 6390 unlock:
2dec18ad826f52 Jiri Pirko 2022-07-28 6391 mutex_unlock(&region->snapshot_lock);
043b3e22768d5d Jakub Kicinski 2020-05-01 @6392 return err;
b9a17abfde842b Jacob Keller 2020-03-26 6393 }

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