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

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
View File

@ -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;
}

45
net/core/devlink.c
View File

@ -11283,55 +11283,28 @@ static struct devlink_port *netdev_to_devlink_port(struct net_device *dev)
return dev->netdev_ops->ndo_get_devlink_port(dev);
}
static struct devlink *netdev_to_devlink(struct net_device *dev)
{
struct devlink_port *devlink_port = netdev_to_devlink_port(dev);
if (!devlink_port)
return NULL;
return devlink_port->devlink;
}
void devlink_compat_running_version(struct net_device *dev,
void devlink_compat_running_version(struct devlink *devlink,
char *buf, size_t len)
{
struct devlink *devlink;
dev_hold(dev);
rtnl_unlock();
devlink = netdev_to_devlink(dev);
if (!devlink || !devlink->ops->info_get)
goto out;
if (!devlink->ops->info_get)
return;
mutex_lock(&devlink->lock);
__devlink_compat_running_version(devlink, buf, len);
mutex_unlock(&devlink->lock);
out:
rtnl_lock();
dev_put(dev);
}
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)
{
struct devlink_flash_update_params params = {};
struct devlink *devlink;
int ret;
dev_hold(dev);
rtnl_unlock();
devlink = netdev_to_devlink(dev);
if (!devlink || !devlink->ops->flash_update) {
ret = -EOPNOTSUPP;
goto out;
}
if (!devlink->ops->flash_update)
return -EOPNOTSUPP;
ret = request_firmware(&params.fw, file_name, devlink->dev);
if (ret)
goto out;
return ret;
mutex_lock(&devlink->lock);
devlink_flash_update_begin_notify(devlink);
@ -11341,10 +11314,6 @@ int devlink_compat_flash_update(struct net_device *dev, const char *file_name)
release_firmware(params.fw);
out:
rtnl_lock();
dev_put(dev);
return ret;
}

36
net/ethtool/ioctl.c
View File

@ -34,12 +34,27 @@
/* State held across locks and calls for commands which have devlink fallback */
struct ethtool_devlink_compat {
struct devlink *devlink;
union {
struct ethtool_flash efl;
struct ethtool_drvinfo info;
};
};
static struct devlink *netdev_to_devlink_get(struct net_device *dev)
{
struct devlink_port *devlink_port;
if (!dev->netdev_ops->ndo_get_devlink_port)
return NULL;
devlink_port = dev->netdev_ops->ndo_get_devlink_port(dev);
if (!devlink_port)
return NULL;
return devlink_try_get(devlink_port->devlink);
}
/*
* Some useful ethtool_ops methods that're device independent.
* If we find that all drivers want to do the same thing here,
@ -751,8 +766,8 @@ ethtool_get_drvinfo(struct net_device *dev, struct ethtool_devlink_compat *rsp)
rsp->info.eedump_len = ops->get_eeprom_len(dev);
if (!rsp->info.fw_version[0])
devlink_compat_running_version(dev, rsp->info.fw_version,
sizeof(rsp->info.fw_version));
rsp->devlink = netdev_to_devlink_get(dev);
return 0;
}
@ -2184,8 +2199,10 @@ static int ethtool_set_value(struct net_device *dev, char __user *useraddr,
static int
ethtool_flash_device(struct net_device *dev, struct ethtool_devlink_compat *req)
{
if (!dev->ethtool_ops->flash_device)
return devlink_compat_flash_update(dev, req->efl.data);
if (!dev->ethtool_ops->flash_device) {
req->devlink = netdev_to_devlink_get(dev);
return 0;
}
return dev->ethtool_ops->flash_device(dev, &req->efl);
}
@ -3027,7 +3044,16 @@ int dev_ethtool(struct net *net, struct ifreq *ifr, void __user *useraddr)
goto exit_free;
switch (ethcmd) {
case ETHTOOL_FLASHDEV:
if (state->devlink)
rc = devlink_compat_flash_update(state->devlink,
state->efl.data);
break;
case ETHTOOL_GDRVINFO:
if (state->devlink)
devlink_compat_running_version(state->devlink,
state->info.fw_version,
sizeof(state->info.fw_version));
if (copy_to_user(useraddr, &state->info, sizeof(state->info))) {
rc = -EFAULT;
goto exit_free;
@ -3036,6 +3062,8 @@ int dev_ethtool(struct net *net, struct ifreq *ifr, void __user *useraddr)
}
exit_free:
if (state->devlink)
devlink_put(state->devlink);
kfree(state);
return rc;
}