Re: [dpdk-dev] [PATCH v8 1/3] lib/lpm: integrate RCU QSBR

[Ruifeng Wang <Ruifeng.Wang@arm.com>]

> -----Original Message-----
> From: David Marchand <david.marchand@redhat.com>
> Sent: Thursday, July 9, 2020 7:50 PM
> To: Ruifeng Wang <Ruifeng.Wang@arm.com>
> Cc: Bruce Richardson <bruce.richardson@intel.com>; Vladimir Medvedkin
> <vladimir.medvedkin@intel.com>; John McNamara
> <john.mcnamara@intel.com>; Marko Kovacevic
> <marko.kovacevic@intel.com>; Ray Kinsella <mdr@ashroe.eu>; Neil Horman
> <nhorman@tuxdriver.com>; dev <dev@dpdk.org>; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>; nd <nd@arm.com>
> Subject: Re: [dpdk-dev] [PATCH v8 1/3] lib/lpm: integrate RCU QSBR
> 
> Hello Ruifeng,
> 
Hi David,

Thanks for your review and suggestions.

> On Thu, Jul 9, 2020 at 10:03 AM Ruifeng Wang <ruifeng.wang@arm.com>
> wrote:
> > diff --git a/lib/librte_lpm/rte_lpm.c b/lib/librte_lpm/rte_lpm.c index
> > 38ab512a4..4fbf5b6df 100644
> > --- a/lib/librte_lpm/rte_lpm.c
> > +++ b/lib/librte_lpm/rte_lpm.c
> > @@ -1,5 +1,6 @@
> >  /* SPDX-License-Identifier: BSD-3-Clause
> >   * Copyright(c) 2010-2014 Intel Corporation
> > + * Copyright(c) 2020 Arm Limited
> >   */
> >
> >  #include <string.h>
> > @@ -39,6 +40,17 @@ enum valid_flag {
> >         VALID
> >  };
> >
> > +/** @internal LPM structure. */
> > +struct __rte_lpm {
> > +       /* LPM metadata. */
> > +       struct rte_lpm lpm;
> > +
> > +       /* RCU config. */
> > +       struct rte_rcu_qsbr *v;         /* RCU QSBR variable. */
> > +       enum rte_lpm_qsbr_mode rcu_mode;/* Blocking, defer queue. */
> > +       struct rte_rcu_qsbr_dq *dq;     /* RCU QSBR defer queue. */
> > +};
> > +
> >  /* Macro to enable/disable run-time checks. */  #if
> > defined(RTE_LIBRTE_LPM_DEBUG)  #include <rte_debug.h> @@ -122,6
> +134,7
> > @@ rte_lpm_create(const char *name, int socket_id,
> >                 const struct rte_lpm_config *config)  {
> >         char mem_name[RTE_LPM_NAMESIZE];
> > +       struct __rte_lpm *internal_lpm = NULL;
> 
> Nit: internal_lpm does not need to be initialised to NULL.
> 
Agreed.

> 
> >         struct rte_lpm *lpm = NULL;
> >         struct rte_tailq_entry *te;
> >         uint32_t mem_size, rules_size, tbl8s_size; @@ -140,12 +153,6
> > @@ rte_lpm_create(const char *name, int socket_id,
> >
> >         snprintf(mem_name, sizeof(mem_name), "LPM_%s", name);
> >
> > -       /* Determine the amount of memory to allocate. */
> > -       mem_size = sizeof(*lpm);
> > -       rules_size = sizeof(struct rte_lpm_rule) * config->max_rules;
> > -       tbl8s_size = (sizeof(struct rte_lpm_tbl_entry) *
> > -                       RTE_LPM_TBL8_GROUP_NUM_ENTRIES * config-
> >number_tbl8s);
> > -
> >         rte_mcfg_tailq_write_lock();
> >
> >         /* guarantee there's no existing */ @@ -161,6 +168,12 @@
> > rte_lpm_create(const char *name, int socket_id,
> >                 goto exit;
> >         }
> >
> > +       /* Determine the amount of memory to allocate. */
> > +       mem_size = sizeof(*internal_lpm);
> > +       rules_size = sizeof(struct rte_lpm_rule) * config->max_rules;
> > +       tbl8s_size = (sizeof(struct rte_lpm_tbl_entry) *
> > +                       RTE_LPM_TBL8_GROUP_NUM_ENTRIES *
> > + config->number_tbl8s);
> > +
> >         /* allocate tailq entry */
> >         te = rte_zmalloc("LPM_TAILQ_ENTRY", sizeof(*te), 0);
> >         if (te == NULL) {
> > @@ -170,22 +183,23 @@ rte_lpm_create(const char *name, int socket_id,
> >         }
> >
> >         /* Allocate memory to store the LPM data structures. */
> > -       lpm = rte_zmalloc_socket(mem_name, mem_size,
> > +       internal_lpm = rte_zmalloc_socket(mem_name, mem_size,
> >                         RTE_CACHE_LINE_SIZE, socket_id);
> > -       if (lpm == NULL) {
> > +       if (internal_lpm == NULL) {
> >                 RTE_LOG(ERR, LPM, "LPM memory allocation failed\n");
> >                 rte_free(te);
> >                 rte_errno = ENOMEM;
> >                 goto exit;
> >         }
> >
> > +       lpm = &internal_lpm->lpm;
> 
> From this point...
> 
> >         lpm->rules_tbl = rte_zmalloc_socket(NULL,
> >                         (size_t)rules_size, RTE_CACHE_LINE_SIZE,
> > socket_id);
> >
> >         if (lpm->rules_tbl == NULL) {
> >                 RTE_LOG(ERR, LPM, "LPM rules_tbl memory allocation failed\n");
> > -               rte_free(lpm);
> > -               lpm = NULL;
> > +               rte_free(internal_lpm);
> > +               internal_lpm = NULL;
> 
> ... lpm is set to &internal_lpm->lpm and will be returned by jumping to the
> exit label.
> So freeing internal_lpm is necessary, but the lpm variable must be set to
> NULL too.
> 
Yes. lpm will be returned instead of internal_lpm. It must be set to NULL.
Will add this in next version.

> 
> >                 rte_free(te);
> >                 rte_errno = ENOMEM;
> >                 goto exit;
> > @@ -197,8 +211,8 @@ rte_lpm_create(const char *name, int socket_id,
> >         if (lpm->tbl8 == NULL) {
> >                 RTE_LOG(ERR, LPM, "LPM tbl8 memory allocation failed\n");
> >                 rte_free(lpm->rules_tbl);
> > -               rte_free(lpm);
> > -               lpm = NULL;
> > +               rte_free(internal_lpm);
> > +               internal_lpm = NULL;
> 
> Ditto.
> 
Will do.
Thanks.

> 
> >                 rte_free(te);
> >                 rte_errno = ENOMEM;
> >                 goto exit;
> 
> --
> David Marchand