在 2021/2/26 23:25, Ferruh Yigit 写道:

On 2/24/2021 1:28 AM, Lijun Ou wrote:

quoted

From: Chengchang Tang <tangchengchang@huawei.com>

After MTU changed, the buffer used to store packets in HW should be
reallocated. And buffer size is allocated based on the maximum frame
size in the PF struct. However, the value of maximum frame size  is
not updated in time when MTU is changed. This would lead to a packet
loss for not enough buffer.

This patch update the maximum frame size before reallocating the HW
buffer. And a rollback operation is added to avoid the side effects
of buffer reallocation failures.

Fixes: 1f5ca0b460cd ("net/hns3: support some device operations")
Fixes: d51867db65c1 ("net/hns3: add initialization")
Cc: stable@dpdk.org

Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Lijun Ou <redacted>

Isn't the patch title should say 'before', like:
net/hns3: fix maximum frame size update _before_ buffer alloc

Or perhaps I get the patch wrong...
.

The expression here may vary from different perspectives. From a 
hardware standpoint, the problem is that the maximum frame size update 
buffer allocation. From a software standpoint, the the buffer size that 
should be allocted depends on the maximum frame size kept in the driver, 
and the problem is caused by the late value update in the driver.