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net: ethtool: keep rtnl_lock for the ioctl self test

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An offline self test that brings the interface down and back up with
netif_close() / netif_open() requires rtnl_lock for both. Since the
ethtool IOCTL path became rtnl-optional for ops-locked drivers, the
ETHTOOL_TEST ioctl runs holding only the netdev instance lock, so on an
ops-locked driver the self test now tears the device down without
rtnl_lock.

With lockdep this reproduces deterministically on every offline self
test on such a driver; note the sole lock held is the instance lock, not
rtnl:

  WARNING: suspicious RCU usage
  net/core/netpoll.c:207 suspicious rcu_dereference_protected() usage!
  1 lock held by ethtool/107:
   #0: (&dev->lock){+.+.}, at: dev_ethtool
  Call Trace:
   netpoll_poll_disable
   __dev_close_many
   netif_close_many
   netif_close
   fbnic_self_test
   dev_ethtool_locked
   dev_ethtool
   dev_ioctl
   sock_ioctl
   __x64_sys_ioctl

Without lockdep the same condition trips ASSERT_RTNL() in
__dev_close_many() / __dev_open(); that check only samples the global
rtnl state, so it can be masked by a concurrent rtnl holder, but the
device is still being reconfigured without the lock it requires.

The ethtool self_test is a legacy ioctl-only command, so an ETHTOOL_TEST
case is only needed on the ioctl path. Add an opt-in bit for drivers whose
self test needs rtnl_lock and set it on the ops-locked drivers whose
offline self test tears the interface down and up:

  - fbnic (ops-locked via queue_mgmt_ops): fbnic_self_test() offline path
    uses netif_close() / netif_open().
  - bnxt (ops-locked via queue_mgmt_ops): bnxt_self_test() offline path
    goes through bnxt_close_nic() / bnxt_half_open_nic() /
    bnxt_half_close_nic() / bnxt_open_nic(), which close and reopen the
    device.

Fixes: f994752b11 ("net: ethtool: optionally skip rtnl_lock on IOCTL path")
Signed-off-by: Alexander Duyck <alexanderduyck@fb.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/178942019771.7700.338431553546884773.stgit@ahduyck-xeon-server.home.arpa
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Alexander Duyck 2026-09-14 14:09:57 -07:00 committed by Jakub Kicinski
parent 95c4d54ed0
commit 1b82958f3f
4 changed files with 8 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
View File

@ -5733,7 +5733,8 @@ const struct ethtool_ops bnxt_ethtool_ops = {
.op_needs_rtnl = ETHTOOL_OP_NEEDS_RTNL_SCHANNELS |
ETHTOOL_OP_NEEDS_RTNL_SRINGPARAM |
ETHTOOL_OP_NEEDS_RTNL_SCOALESCE |
ETHTOOL_OP_NEEDS_RTNL_RSS,
ETHTOOL_OP_NEEDS_RTNL_RSS |
ETHTOOL_OP_NEEDS_RTNL_TEST,
.supported_coalesce_params = ETHTOOL_COALESCE_USECS |
ETHTOOL_COALESCE_MAX_FRAMES |
ETHTOOL_COALESCE_USECS_IRQ |

3
drivers/net/ethernet/meta/fbnic/fbnic_ethtool.c
View File

@ -2025,7 +2025,8 @@ static const struct ethtool_ops fbnic_ethtool_ops = {
ETHTOOL_OP_NEEDS_RTNL_SPAUSEPARAM |
ETHTOOL_OP_NEEDS_RTNL_SCHANNELS |
ETHTOOL_OP_NEEDS_RTNL_SRINGPARAM |
ETHTOOL_OP_NEEDS_RTNL_GLINK,
ETHTOOL_OP_NEEDS_RTNL_GLINK |
ETHTOOL_OP_NEEDS_RTNL_TEST,
.get_drvinfo = fbnic_get_drvinfo,
.get_regs_len = fbnic_get_regs_len,
.get_regs = fbnic_get_regs,

2
include/linux/ethtool.h
View File

@ -944,6 +944,7 @@ struct kernel_ethtool_ts_info {
#define ETHTOOL_OP_NEEDS_RTNL_SPAUSEPARAM BIT(6)
#define ETHTOOL_OP_NEEDS_RTNL_RSS BIT(7)
#define ETHTOOL_OP_NEEDS_RTNL_GLINK BIT(8)
#define ETHTOOL_OP_NEEDS_RTNL_TEST BIT(9)
/**
* struct ethtool_ops - optional netdev operations
@ -981,6 +982,7 @@ struct kernel_ethtool_ts_info {
* - netdev_update_features()
* - netif_set_real_num_tx_queues()
* - ethtool_op_get_link() (syncs link watch under rtnl_lock)
* - netif_open() / netif_close() (used by @self_test)
*
* @get_drvinfo: Report driver/device information. Modern drivers no
* longer have to implement this callback. Most fields are

2
net/ethtool/common.h
View File

@ -163,6 +163,8 @@ ethtool_ioctl_needs_rtnl(const struct net_device *dev, u32 ethcmd)
return ops->op_needs_rtnl & ETHTOOL_OP_NEEDS_RTNL_RSS;
case ETHTOOL_GLINK:
return ops->op_needs_rtnl & ETHTOOL_OP_NEEDS_RTNL_GLINK;
case ETHTOOL_TEST:
return ops->op_needs_rtnl & ETHTOOL_OP_NEEDS_RTNL_TEST;
}
return false;
}