Re: [dpdk-dev] [EXT] [PATCH 1/5] examples/l2fwd-event: free resources in case of error

[Sunil Kumar Kori <skori@marvell.com>]

>-----Original Message-----
>From: Muhammad Bilal <m.bilal@emumba.com>
>Sent: Monday, June 15, 2020 5:30 PM
>To: Sunil Kumar Kori <skori@marvell.com>
>Cc: declan.doherty@intel.com; tomasz.kantecki@intel.com; Pavan Nikhilesh
>Bhagavatula <pbhagavatula@marvell.com>; dev@dpdk.org;
>jgrajcia@cisco.com; vipin.varghese@intel.com
>Subject: Re: [EXT] [PATCH 1/5] examples/l2fwd-event: free resources in case
>of error
>
>On Wed, Jun 10, 2020 at 3:01 PM Sunil Kumar Kori <skori@marvell.com>
>wrote:
>>
>> >-----Original Message-----
>> >From: Muhammad Bilal <m.bilal@emumba.com>
>> >Sent: Tuesday, June 2, 2020 5:57 PM
>> >To: Sunil Kumar Kori <skori@marvell.com>
>> >Cc: declan.doherty@intel.com; tomasz.kantecki@intel.com; Pavan
>> >Nikhilesh Bhagavatula <pbhagavatula@marvell.com>; dev@dpdk.org;
>> >jgrajcia@cisco.com; vipin.varghese@intel.com
>> >Subject: Re: [EXT] [PATCH 1/5] examples/l2fwd-event: free resources
>> >in case of error
>> >
>> >On Tue, May 19, 2020 at 2:35 PM Sunil Kumar Kori <skori@marvell.com>
>> >wrote:
>> >>
>> >> >-----Original Message-----
>> >> >From: Muhammad Bilal <m.bilal@emumba.com>
>> >> >Sent: Tuesday, May 19, 2020 2:25 PM
>> >> >To: declan.doherty@intel.com; tomasz.kantecki@intel.com; Pavan
>> >> >Nikhilesh Bhagavatula <pbhagavatula@marvell.com>; Sunil Kumar Kori
>> >> ><skori@marvell.com>
>> >> >Cc: dev@dpdk.org; Muhammad Bilal <m.bilal@emumba.com>
>> >> >Subject: [EXT] [PATCH 1/5] examples/l2fwd-event: free resources in
>> >> >case of error
>> >> >
>> >> >External Email
>> >> >
>> >> >------------------------------------------------------------------
>> >> >---
>> >> >- Freeing the resources and call rte_eal_cleanup in case of error
>> >> >exit.
>> >> >Signed-off-by: Muhammad Bilal <m.bilal@emumba.com>
>> >> >---
>> >> > examples/l2fwd-event/main.c | 43
>> >> >++++++++++++++++++++++++++++++-------
>> >> > 1 file changed, 35 insertions(+), 8 deletions(-)
>> >> >
>> >> >diff --git a/examples/l2fwd-event/main.c
>> >> >b/examples/l2fwd-event/main.c index 9593ef11e..442a664e9 100644
>> >> >--- a/examples/l2fwd-event/main.c
>> >> >+++ b/examples/l2fwd-event/main.c
>> >> >@@ -556,13 +556,26 @@ signal_handler(int signum)
>> >> >       }
>> >> > }
>> >> >
>> >> >+static void
>> >> >+stop_and_close_eth_dev(uint16_t portid) {
>> >> >+      RTE_ETH_FOREACH_DEV(portid) {
>> >> >+              printf("Closing port %d...", portid);
>> >> >+              rte_eth_dev_stop(portid);
>> >> >+              rte_eth_dev_close(portid);
>> >> >+              printf(" Done\n");
>> >> >+      }
>> >> >+      rte_eal_cleanup();
>> >> >+}
>> >> >+
>> >> > int
>> >> > main(int argc, char **argv)
>> >> > {
>> >> >       struct l2fwd_resources *rsrc;
>> >> >       uint16_t nb_ports_available = 0;
>> >> >       uint32_t nb_ports_in_mask = 0;
>> >> >-      uint16_t port_id, last_port;
>> >> >+      uint16_t port_id = 0;
>> >> >+      uint16_t last_port;
>> >> >       uint32_t nb_mbufs;
>> >> >       uint16_t nb_ports;
>> >> >       int i, ret;
>> >> >@@ -581,20 +594,26 @@ main(int argc, char **argv)
>> >> >
>> >> >       /* parse application arguments (after the EAL ones) */
>> >> >       ret = l2fwd_event_parse_args(argc, argv, rsrc);
>> >> >-      if (ret < 0)
>> >> >+      if (ret < 0) {
>> >> >+              stop_and_close_eth_dev(port_id);
>> >> >               rte_panic("Invalid L2FWD arguments\n");
>> >> >+      }
>> >> >
>> >Yes you are right we should use rte_exit instead of rte_panic, as
>> >rte_exit internally calls rte_eal_cleanup function.
>> >> IMO, up to this point only eal_init is done so rte_eal_cleanup will
>> >> be
>> >sufficient for this.
>> >> Also another way to handle this, use rte_exit instead rte_panic.
>> >> rte_exit internally calls rte_eal_cleanup. Refer l2fwd.
>> >>
>> >> Also I think, it is better to release the relevant resources on error.
>> >Here I'm solving the problem reported in bugzilla id 437. The bug was
>> >that if we use --vdev=net_memif with l2fwd application (and with its
>> >other variants) then a socket is created by memif PMD, after
>> >rte_eal_init function has run successfully. And if an error occurs
>> >then the application exits without freeing the resources (socket). On
>> >running the application 2nd time we get an error of "socket already exists".
>> >As in the previous version of patch "
>> >https://urldefense.proofpoint.com/v2/url?u=http-
>>
>>3A__patches.dpdk.org_patch_70081_&d=DwIBaQ&c=nKjWec2b6R0mOyPaz7
>x
>>
>>tfQ&r=dXeXaAMkP5COgn1zxHMyaF1_d9IIuq6vHQO6NrIPjaE&m=XKcRI2e7sM
>v
>>
>>Y0nGabnBQl_Q8meL03FXFAjeNGdCV91A&s=TKq1J0W3QbnkeuG4c63payDW
>c
>> >Pc4zTg4DumA95RVzwg&e=  " it was recommended to clean the resources
>> >when an error occurs.
>> >
>> >Here only using rte_eal_cleanup() is not solving the problem as using
>> >memif PMD is creating a socket and it's only cleaned when
>> >rte_eth_dev_close(portid) function is called. so that's why using it
>> >along with rte_exit or rte_panic.
>>
>>
>> Understood but I am only thinking from user's perspective that user
>> didn't do rte_eth_dev_configure and related APIs so closing the device
>> using rte_eth_dev_close does not look good.
>> May be other's (eal and memif PMD owners) can suggest something better.
>> Please redirect this query to them for suggestions also.
>Maintainer also recommended to call rte_eth_dev_close() for this problem in
>bug No. 437 Here : https://urldefense.proofpoint.com/v2/url?u=https-
>3A__bugs.dpdk.org_show-5Fbug.cgi-3Fid-3D437-
>23c1&d=DwIBaQ&c=nKjWec2b6R0mOyPaz7xtfQ&r=dXeXaAMkP5COgn1zxHMy
>aF1_d9IIuq6vHQO6NrIPjaE&m=C6PYaZqbOP-IfP6yK-
>nkxpSLonovGalGzl9QJ03qBmU&s=SEiTU3-
>EhOV5r16Kk9ZbW67E_dzuHvls4Fn41WyfCN0&e=

In mentioned link, I see that Vipin has also suggested to clean this resource in memif PMD
But did not found any reason to drop that idea. I am still in favor of this.
Also as a query, I see that changes are only l2fwd and its variants. 
Is this problem not applicable to other applications where memif is used ?

>>
>> >>
>> >> >       printf("MAC updating %s\n", rsrc->mac_updating ? "enabled" :
>> >> >                       "disabled");
>> >> >
>> >> >       nb_ports = rte_eth_dev_count_avail();
>> >> >-      if (nb_ports == 0)
>> >> >+      if (nb_ports == 0) {
>> >> >+              stop_and_close_eth_dev(port_id);
>> >> >               rte_panic("No Ethernet ports - bye\n");
>> >> >+      }
>> >> >
>> >> Same as above.
>> >>
>> >> >       /* check port mask to possible port mask */
>> >> >-      if (rsrc->enabled_port_mask & ~((1 << nb_ports) - 1))
>> >> >+      if (rsrc->enabled_port_mask & ~((1 << nb_ports) - 1)) {
>> >> >+              stop_and_close_eth_dev(port_id);
>> >> >               rte_panic("Invalid portmask; possible (0x%x)\n",
>> >> >                       (1 << nb_ports) - 1);
>> >> >+      }
>> >> >
>> >> Same as above.
>> >>
>> >> >       if (!rsrc->port_pairs) {
>> >> >               last_port = 0;
>> >> >@@ -621,8 +640,10 @@ main(int argc, char **argv)
>> >> >                       rsrc->dst_ports[last_port] = last_port;
>> >> >               }
>> >> >       } else {
>> >> >-              if (check_port_pair_config(rsrc) < 0)
>> >> >+              if (check_port_pair_config(rsrc) < 0) {
>> >> >+                      stop_and_close_eth_dev(port_id);
>> >> >                       rte_panic("Invalid port pair config\n");
>> >> >+              }
>> >> >       }
>> >> >
>> >> >       nb_mbufs = RTE_MAX(nb_ports * (RTE_TEST_RX_DESC_DEFAULT +
>> >@@
>> >> >-634,12 +655,16 @@ main(int argc, char **argv)
>> >> >       rsrc->pktmbuf_pool = rte_pktmbuf_pool_create("mbuf_pool",
>> >> >                       nb_mbufs, MEMPOOL_CACHE_SIZE, 0,
>> >> >                       RTE_MBUF_DEFAULT_BUF_SIZE, rte_socket_id());
>> >> >-      if (rsrc->pktmbuf_pool == NULL)
>> >> >+      if (rsrc->pktmbuf_pool == NULL) {
>> >> >+              stop_and_close_eth_dev(port_id);
>> >> >               rte_panic("Cannot init mbuf pool\n");
>> >> >+      }
>> >> >
>> >> >       nb_ports_available = l2fwd_event_init_ports(rsrc);
>> >> >-      if (!nb_ports_available)
>> >> >+      if (!nb_ports_available) {
>> >> >+              stop_and_close_eth_dev(port_id);
>> >> >               rte_panic("All available ports are disabled. Please
>> >> >set portmask.\n");
>> >> >+      }
>> >> >
>> >> >       /* Configure eventdev parameters if required */
>> >> >       if (rsrc->event_mode)
>> >> >@@ -659,9 +684,11 @@ main(int argc, char **argv)
>> >> >                       continue;
>> >> >
>> >> >               ret = rte_eth_dev_start(port_id);
>> >> >-              if (ret < 0)
>> >> >+              if (ret < 0) {
>> >> >+                      stop_and_close_eth_dev(port_id);
>> >> >                       rte_panic("rte_eth_dev_start:err=%d,
>> >> >port=%u\n", ret,
>> >> >                                 port_id);
>> >> >+              }
>> >> >       }
>> >> >
>> >> >       if (rsrc->event_mode)
>> >> >--
>> >> >2.17.1
>> >>