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

[Muhammad Bilal <m.bilal@emumba.com>]

On Tue, Jun 16, 2020 at 10:53 AM Sunil Kumar Kori <skori@marvell.com> wrote:
>
> >-----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.

You are right, Vipin initially recommended change in Memif PMD but
later agreed upon cleaning the resources in applications.

> 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 ?

This problem is applicable to other applications where memif is used.
We are working on other applications as time permits, Some patches
already submitted e.g:
http://patches.dpdk.org/project/dpdk/list/?series=10458

>
> >>
> >> >>
> >> >> >       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
> >> >>