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

[Chaoyong He]

> 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 at 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 at corigine.com
> >>> Cc: stable at dpdk.org
> >>>
> >>> Signed-off-by: Long Wu <long.wu at corigine.com>
> >>> Reviewed-by: Chaoyong He <chaoyong.he at corigine.com>
> >>> Reviewed-by: Peng Zhang <peng.zhang at 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.

(gdb) until 384
nfp_flower_repr_dev_close (dev=0x7f839aed2340 <rte_eth_devices>)
    at ../drivers/net/nfp/flower/nfp_flower_representor.c:384
384             nfp_flower_repr_free(repr, repr->repr_type);
(gdb) s
nfp_flower_repr_free (repr=0x17c49c800, repr_type=NFP_REPR_TYPE_PF)
    at ../drivers/net/nfp/flower/nfp_flower_representor.c:328
328             switch (repr_type) {
(gdb) n
333                     nfp_flower_pf_repr_uninit(repr->eth_dev);
(gdb) s
nfp_flower_pf_repr_uninit (eth_dev=0x7f839aed2340 <rte_eth_devices>)
    at ../drivers/net/nfp/flower/nfp_flower_representor.c:317
317             struct nfp_flower_representor *repr = eth_dev->data->dev_private;
(gdb) n
319             repr->app_fw_flower->pf_repr = NULL;
(gdb) p eth_dev->data->dev_private
$4 = (void *) 0x17c49c800
(gdb) p repr
$5 = (struct nfp_flower_representor *) 0x17c49c800
(gdb) p repr->app_fw_flower->pf_repr
$6 = (struct nfp_flower_representor *) 0x17c49c800

As what I said, although I assign NULL to one of the pointers `repr->app_fw_flower->pf_repr`, it still can be access by the other one `eth_dev->data->dev_private`.

(gdb) fin
Run till exit from #0  nfp_flower_pf_repr_uninit (eth_dev=0x7f839aed2340 <rte_eth_devices>)
    at ../drivers/net/nfp/flower/nfp_flower_representor.c:319
nfp_flower_repr_free (repr=0x17c49c800, repr_type=NFP_REPR_TYPE_PF)
    at ../drivers/net/nfp/flower/nfp_flower_representor.c:334
334                     break;
Value returned is $7 = 0
(gdb) fin
Run till exit from #0  nfp_flower_repr_free (repr=0x17c49c800, repr_type=NFP_REPR_TYPE_PF)
    at ../drivers/net/nfp/flower/nfp_flower_representor.c:334
nfp_flower_repr_dev_close (dev=0x7f839aed2340 <rte_eth_devices>)
    at ../drivers/net/nfp/flower/nfp_flower_representor.c:386
386             for (i = 0; i < MAX_FLOWER_VFS; i++) {
(gdb) b rte_eth_dev_release_port
Breakpoint 2 at 0x7f839ae0d0d5: file ../lib/ethdev/ethdev_driver.c, line 230.
(gdb) c
Continuing.

Thread 1 "dpdk-testpmd" hit Breakpoint 2, rte_eth_dev_release_port (eth_dev=0x7f839aed2340 <rte_eth_devices>)
    at ../lib/ethdev/ethdev_driver.c:230
230             if (eth_dev == NULL)
(gdb) p eth_dev
$8 = (struct rte_eth_dev *) 0x7f839aed2340 <rte_eth_devices>
(gdb) until 267
rte_eth_dev_release_port (eth_dev=0x7f839aed2340 <rte_eth_devices>) at ../lib/ethdev/ethdev_driver.c:267
267                     rte_free(eth_dev->data->dev_private);
(gdb) p eth_dev->data->dev_private
$9 = (void *) 0x17c49c800
(gdb)

And here, we free this block of memory, and no memory leak happens, I think.