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

[Chaoyong He <chaoyong.he@corigine.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()'?

Sorry, I'm not understanding this.
The 'dev_private' is a 'struct nfp_flower_representor *', and it will be freed in 'rte_eth_dev_release_port()'.
What I freed in 'nfp_pf_uninit()' is a 'struct nfp_pf_dev *', so I'm not catch your point about this.

> Won't removing 'rte_free(pf_dev);' from 'nfp_pf_uninit()' will have the same
> effect, instead of setting it NULL in advance?
> 

If I remove the 'rte_free(pf_dev);' from 'nfp_pf_uninit()', there will be a memory leak as no one will free it, and actually I'm not 'setting it NULL in advance'.

359             repr = dev->data->dev_private;
360             app_fw_flower = repr->app_fw_flower;
361             hw = app_fw_flower->pf_hw;
362             pf_dev = hw->pf_dev;

Maybe you just confuse the 'pf_repr' and 'pf_dev'? Just a guess.