Re: [PATCH 2/3] net/nfp: fix free resource problem

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 1/9/2024 7:56 AM, Chaoyong He wrote:
>> On 12/18/2023 1:50 AM, Chaoyong He wrote:
>>>> On 12/14/2023 10:24 AM, Chaoyong He wrote:
>>>>> From: Long Wu <long.wu@corigine.com>
>>>>>
>>>>> Set the representor array to NULL to avoid that close interface does
>>>>> not free some resource.
>>>>>
>>>>> Fixes: a135bc1644d6 ("net/nfp: fix resource leak for flower
>>>>> firmware")
>>>>> Cc: chaoyong.he@corigine.com
>>>>> Cc: stable@dpdk.org
>>>>>
>>>>> Signed-off-by: Long Wu <long.wu@corigine.com>
>>>>> Reviewed-by: Chaoyong He <chaoyong.he@corigine.com>
>>>>> Reviewed-by: Peng Zhang <peng.zhang@corigine.com>
>>>>> ---
>>>>>  drivers/net/nfp/flower/nfp_flower_representor.c | 15
>>>>> ++++++++++++++-
>>>>>  1 file changed, 14 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/net/nfp/flower/nfp_flower_representor.c
>>>>> b/drivers/net/nfp/flower/nfp_flower_representor.c
>>>>> index 27ea3891bd..5f7c1fa737 100644
>>>>> --- a/drivers/net/nfp/flower/nfp_flower_representor.c
>>>>> +++ b/drivers/net/nfp/flower/nfp_flower_representor.c
>>>>> @@ -294,17 +294,30 @@ nfp_flower_repr_tx_burst(void *tx_queue,
>>>>> static int  nfp_flower_repr_uninit(struct rte_eth_dev *eth_dev)  {
>>>>> +	uint16_t index;
>>>>>  	struct nfp_flower_representor *repr;
>>>>>
>>>>>  	repr = eth_dev->data->dev_private;
>>>>>  	rte_ring_free(repr->ring);
>>>>>
>>>>> +	if (repr->repr_type == NFP_REPR_TYPE_PHYS_PORT) {
>>>>> +		index = NFP_FLOWER_CMSG_PORT_PHYS_PORT_NUM(repr-
>>>>> port_id);
>>>>> +		repr->app_fw_flower->phy_reprs[index] = NULL;
>>>>> +	} else {
>>>>> +		index = repr->vf_id;
>>>>> +		repr->app_fw_flower->vf_reprs[index] = NULL;
>>>>> +	}
>>>>> +
>>>>>  	return 0;
>>>>>  }
>>>>>
>>>>>  static int
>>>>> -nfp_flower_pf_repr_uninit(__rte_unused struct rte_eth_dev *eth_dev)
>>>>> +nfp_flower_pf_repr_uninit(struct rte_eth_dev *eth_dev)
>>>>>  {
>>>>> +	struct nfp_flower_representor *repr = eth_dev->data->dev_private;
>>>>> +
>>>>> +	repr->app_fw_flower->pf_repr = NULL;
>>>>>
>>>>
>>>> Here it is assigned to NULL but is it freed? If freed, why not set to
>>>> NULL where it is freed?
>>>>
>>>> Same for above phy_reprs & vf_reprs.
>>>
>>> The whole invoke view:
>>> rte_eth_dev_close()
>>>     --> nfp_flower_repr_dev_close()
>>>         --> nfp_flower_repr_free()
>>>             --> nfp_flower_pf_repr_uninit()
>>>             --> nfp_flower_repr_uninit()
>>>            // In these two functions, we just assigned to NULL but not freed yet.
>>>            // It is still refer by the `eth_dev->data->dev_private`.
>>>     --> rte_eth_dev_release_port()
>>>         --> rte_free(eth_dev->data->dev_private);
>>>         // And here it is really freed (by the rte framework).
>>>
>>
>> 'rte_eth_dev_release_port()' frees the device private data, but not all pointers,
>> like 'repr->app_fw_flower->pf_repr', in the struct are freed, it is dev_close() or
>> unint() functions responsibility.
>>
>> Can you please double check if
>> 'eth_dev->data->dev_private->app_fw_flower->pf_repr' freed or not?
> 
> (gdb) b nfp_flower_repr_dev_close
> Breakpoint 1 at 0x7f839a4ad37f: file ../drivers/net/nfp/flower/nfp_flower_representor.c, line 356.
> (gdb) c
> Continuing.
> 
> Thread 1 "dpdk-testpmd" hit Breakpoint 1, nfp_flower_repr_dev_close (dev=0x7f839aed2340 <rte_eth_devices>)
>     at ../drivers/net/nfp/flower/nfp_flower_representor.c:356
> 356             if (rte_eal_process_type() != RTE_PROC_PRIMARY)
> (gdb) n
> 359             repr = dev->data->dev_private;
> (gdb)
> 360             app_fw_flower = repr->app_fw_flower;
> (gdb)
> 361             hw = app_fw_flower->pf_hw;
> (gdb)
> 362             pf_dev = hw->pf_dev;
> (gdb)
> 368             nfp_net_disable_queues(dev);
> (gdb) p repr
> $1 = (struct nfp_flower_representor *) 0x17c49c800
> (gdb) p dev->data->dev_private
> $2 = (void *) 0x17c49c800
> (gdb) p repr->app_fw_flower->pf_repr
> $3 = (struct nfp_flower_representor *) 0x17c49c800
> 
> As we can see, these three pointers point the same block of memory.
> 

Ahh, I missed that 'repr->app_fw_flower->pf_repr' points to
'dev_private', so your code makes sense.

But if it is 'dev_private', why free it in 'nfp_pf_uninit()' as it will
be freed by 'rte_eth_dev_release_port()'?
Won't removing 'rte_free(pf_dev);' from 'nfp_pf_uninit()' will have the
same effect, instead of setting it NULL in advance?