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ethtool: don't drop the rtnl_lock half way thru the ioctl

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devlink compat code needs to drop rtnl_lock to take
devlink->lock to ensure correct lock ordering.

This is problematic because we're not strictly guaranteed
that the netdev will not disappear after we re-lock.
It may open a possibility of nested ->begin / ->complete
calls.

Instead of calling into devlink under rtnl_lock take
a ref on the devlink instance and make the call after
we've dropped rtnl_lock.

We (continue to) assume that netdevs have an implicit
reference on the devlink returned from ndo_get_devlink_port

Note that ndo_get_devlink_port will now get called
under rtnl_lock. That should be fine since none of
the drivers seem to be taking serious locks inside
ndo_get_devlink_port.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jakub Kicinski
2021-10-30 10:18:51 -07:00
committed by David S. Miller
parent 46db1b77cd
commit 1af0a0948e
3 changed files with 43 additions and 46 deletions
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8
include/net/devlink.h
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@@ -1729,9 +1729,9 @@ devlink_trap_policers_unregister(struct devlink *devlink,
struct devlink *__must_check devlink_try_get(struct devlink *devlink);
void devlink_put(struct devlink *devlink);
void devlink_compat_running_version(struct net_device *dev,
void devlink_compat_running_version(struct devlink *devlink,
char *buf, size_t len);
int devlink_compat_flash_update(struct net_device *dev, const char *file_name);
int devlink_compat_flash_update(struct devlink *devlink, const char *file_name);
int devlink_compat_phys_port_name_get(struct net_device *dev,
char *name, size_t len);
int devlink_compat_switch_id_get(struct net_device *dev,
@@ -1749,12 +1749,12 @@ static inline void devlink_put(struct devlink *devlink)
}
static inline void
devlink_compat_running_version(struct net_device *dev, char *buf, size_t len)
devlink_compat_running_version(struct devlink *devlink, char *buf, size_t len)
{
}
static inline int
devlink_compat_flash_update(struct net_device *dev, const char *file_name)
devlink_compat_flash_update(struct devlink *devlink, const char *file_name)
{
return -EOPNOTSUPP;
}