The problem is that I can't see how the API can ever provide accurate
information. By the time you have the information it is potentially
stale. There really isn't a way to control if a slave is active since
that is protocol dependent.
rte_eth_bond_slaves_get() is safer in the sense that you control when
the slaves are added and removed from the bonding group. You can ensure
that you get a consistent answer.
Hopefully your protocol doesn't especially care if the slave is active
or not. You are sending the packets via rte_eth_bond_8023ad_ext_slow()?
On 11/30/18 12:50 AM, Linhaifeng wrote:
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:3ch...@gmail.com]
发送时间: 2018年11月30日 11:27
收件人: Linhaifeng <haifeng....@huawei.com>; dev@dpdk.org
抄送: ch...@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....@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
