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SubjectRe: [PATCHv2 net] bonding: fix missed rcu protection
From
On 5/17/22 22:18, Hangbin Liu wrote:
> On Tue, May 17, 2022 at 01:32:58PM -0400, Jonathan Toppins wrote:
>> Signed-off-by: Jonathan Toppins <jtoppins@redhat.com>
>> ---
>> RESEND, list still didn't receive my last version
>>
>> The diffstat is slightly larger but IMO a slightly more readable version.
>> When I was reading v2 I found myself jumping around.
>
> Hi Jon,
>
> Thanks for the commit. But..
>
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index 38e152548126..f9d27b63c454 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -5591,23 +5591,32 @@ static int bond_ethtool_get_ts_info(struct net_device *bond_dev,
>> const struct ethtool_ops *ops;
>> struct net_device *real_dev;
>> struct phy_device *phydev;
>> + int ret = 0;
>>
>> + rcu_read_lock();
>> real_dev = bond_option_active_slave_get_rcu(bond);
>> - if (real_dev) {
>> - ops = real_dev->ethtool_ops;
>> - phydev = real_dev->phydev;
>> -
>> - if (phy_has_tsinfo(phydev)) {
>> - return phy_ts_info(phydev, info);
>> - } else if (ops->get_ts_info) {
>> - return ops->get_ts_info(real_dev, info);
>> - }
>> - }
>> + if (real_dev)
>> + dev_hold(real_dev);
>> + rcu_read_unlock();
>> +
>> + if (!real_dev)
>> + goto software;
>>
>> + ops = real_dev->ethtool_ops;
>> + phydev = real_dev->phydev;
>> +
>> + if (phy_has_tsinfo(phydev))
>> + ret = phy_ts_info(phydev, info);
>> + else if (ops->get_ts_info)
>> + ret = ops->get_ts_info(real_dev, info);
> else {
> dev_put(real_dev);
> goto software;
> }
>
> Here we need another check and goto software if !phy_has_tsinfo() and
> no ops->get_ts_info. With this change we also have 2 goto and dev_put().

Ah yes. I cannot think of a way to make this simpler. The patch below
looks good.

>
>> +
>> + dev_put(real_dev);
>> + return ret;
>> +
>> +software:
>> info->so_timestamping = SOF_TIMESTAMPING_RX_SOFTWARE |
>> SOF_TIMESTAMPING_SOFTWARE;
>> info->phc_index = -1;
>> -
>> return 0;
>> }
>
> As Jakub remind, dev_hold() and dev_put() can take NULL now. So how about
> this new patch:
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 38e152548126..b5c5196e03ee 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -5591,16 +5591,23 @@ static int bond_ethtool_get_ts_info(struct net_device *bond_dev,
> const struct ethtool_ops *ops;
> struct net_device *real_dev;
> struct phy_device *phydev;
> + int ret = 0;
>
> + rcu_read_lock();
> real_dev = bond_option_active_slave_get_rcu(bond);
> + dev_hold(real_dev);
> + rcu_read_unlock();
> +
> if (real_dev) {
> ops = real_dev->ethtool_ops;
> phydev = real_dev->phydev;
>
> if (phy_has_tsinfo(phydev)) {
> - return phy_ts_info(phydev, info);
> + ret = phy_ts_info(phydev, info);
> + goto out;
> } else if (ops->get_ts_info) {
> - return ops->get_ts_info(real_dev, info);
> + ret = ops->get_ts_info(real_dev, info);
> + goto out;
> }
> }
>
> @@ -5608,7 +5615,9 @@ static int bond_ethtool_get_ts_info(struct net_device *bond_dev,
> SOF_TIMESTAMPING_SOFTWARE;
> info->phc_index = -1;
>
> - return 0;
> +out:
> + dev_put(real_dev);
> + return ret;
> }
>
> Thanks
> Hangbin
>

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