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: 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=nKjWec2b6R0mOyPaz7x
>tfQ&r=dXeXaAMkP5COgn1zxHMyaF1_d9IIuq6vHQO6NrIPjaE&m=XKcRI2e7sMv
>Y0nGabnBQl_Q8meL03FXFAjeNGdCV91A&s=TKq1J0W3QbnkeuG4c63payDWc
>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.

>>
>> >       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
>>