[dpdk-dev] 答复: [PATCH] net/bonding: fix double fetch for active_slave_count
Linhaifeng
haifeng.lin at huawei.com
Fri Nov 30 06:50:13 CET 2018
Hi, Chars
Thank you.
I use it for send pkts to the dedicated queue of slaves.
Maybe i should not use it. I would though another way.
-----邮件原件-----
发件人: Chas Williams [mailto:3chas3 at gmail.com]
发送时间: 2018年11月30日 11:27
收件人: Linhaifeng <haifeng.lin at huawei.com>; dev at dpdk.org
抄送: chas3 at att.com
主题: Re: [dpdk-dev] [PATCH] net/bonding: fix double fetch for active_slave_count
I guess this is slightly more correct. There is still a race here though.
After you make your copy of active_slave_count, the number of active slaves could go to 0 and the memcpy() would copy an invalid element, acitve_slaves[0]. There is no simple fix to this problem. Your patch reduces the opportunity for a race but doesn't eliminate it.
What you are using this API for?
On 11/29/18 12:32 AM, Haifeng Lin wrote:
> 1. when memcpy slaves the internals->active_slave_count 1 2. return
> internals->active_slave_count is 2 3. the slaves[1] would be a random
> invalid value
>
> Signed-off-by: Haifeng Lin <haifeng.lin at huawei.com>
> ---
> drivers/net/bonding/rte_eth_bond_api.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/bonding/rte_eth_bond_api.c
> b/drivers/net/bonding/rte_eth_bond_api.c
> index 21bcd50..ed7b02e 100644
> --- a/drivers/net/bonding/rte_eth_bond_api.c
> +++ b/drivers/net/bonding/rte_eth_bond_api.c
> @@ -815,6 +815,7 @@
> uint16_t len)
> {
> struct bond_dev_private *internals;
> + uint16_t active_slave_count;
>
> if (valid_bonded_port_id(bonded_port_id) != 0)
> return -1;
> @@ -824,13 +825,14 @@
>
> internals = rte_eth_devices[bonded_port_id].data->dev_private;
>
> - if (internals->active_slave_count > len)
> + active_slave_count = internals->active_slave_count;
> + if (active_slave_count > len)
> return -1;
>
> memcpy(slaves, internals->active_slaves,
> - internals->active_slave_count * sizeof(internals->active_slaves[0]));
> + active_slave_count * sizeof(internals->active_slaves[0]));
>
> - return internals->active_slave_count;
> + return active_slave_count;
> }
>
> int
>
More information about the dev
mailing list