[ovs-dev] [PATCH 1/2] dpif-netdev: Purge all ukeys when reconfigure pmd.

Alex Wang alexw at nicira.com
Tue Aug 11 18:06:06 UTC 2015


Thx, IIya for the review, please see my reply below,



On Tue, Aug 11, 2015 at 4:41 AM, Ilya Maximets <i.maximets at samsung.com>
wrote:

> On 11.08.2015 05:47, Alex Wang wrote:
> > When dpdk configuration changes, all pmd threads are recreated
> > and rx queues of each port are reloaded.  After this process,
> > rx queue could be mapped to a different pmd thread other than
> > the one before reconfiguration.  However, this is totally
> > transparent to ofproto layer modules.  So, if the ofproto-dpif-upcall
> > module still holds ukeys generated before pmd thread recreation,
> > this old ukey will collide with the ukey for the new upcalls
> > from same traffic flow, causing flow installation failure.
> >
> > To fix the bug, this commit adds a new call-back function
> > in dpif layer for notifying upper layer the purging of datapath
> > (e.g. pmd threads recreation in dpif-netdev).  So, the
> > ofproto-dpif-upcall module can react properly with deleting
> > all the ukeys and with collecting all flows' last stats.
> >
> > Reported-by: Ilya Maximets <i.maximets at samsung.com>
> > Signed-off-by: Alex Wang <alexw at nicira.com>
> > ---
> >  lib/dpif-netdev.c             |   25 +++++++++++++++++++++++++
> >  lib/dpif-netlink.c            |    1 +
> >  lib/dpif-provider.h           |   11 ++++++++++-
> >  lib/dpif.c                    |    8 ++++++++
> >  lib/dpif.h                    |   12 ++++++++++++
> >  ofproto/ofproto-dpif-upcall.c |   16 ++++++++++++++++
> >  6 files changed, 72 insertions(+), 1 deletion(-)
> >
> > diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> > index c144352..a54853f 100644
> > --- a/lib/dpif-netdev.c
> > +++ b/lib/dpif-netdev.c
> > @@ -203,6 +203,11 @@ struct dp_netdev {
> >      upcall_callback *upcall_cb;  /* Callback function for executing
> upcalls. */
> >      void *upcall_aux;
> >
> > +    /* Callback function for notifying the purging of dp flows (during
> > +     * reseting pmd threads). */
> > +    dp_purge_callback *dp_purge_cb;
> > +    void *dp_purge_aux;
> > +
> >      /* Stores all 'struct dp_netdev_pmd_thread's. */
> >      struct cmap poll_threads;
> >
> > @@ -223,6 +228,8 @@ struct dp_netdev {
> >
> >  static struct dp_netdev_port *dp_netdev_lookup_port(const struct
> dp_netdev *dp,
> >                                                      odp_port_t);
> > +static void dp_netdev_disable_upcall(struct dp_netdev *);
> > +static void dp_netdev_enable_upcall(struct dp_netdev *);
> >
> >  enum dp_stat_type {
> >      DP_STAT_EXACT_HIT,          /* Packets that had an exact match
> (emc). */
> > @@ -2440,10 +2447,18 @@ dpif_netdev_pmd_set(struct dpif *dpif, unsigned
> int n_rxqs, const char *cmask)
> >          free(dp->pmd_cmask);
> >          dp->pmd_cmask = cmask ? xstrdup(cmask) : NULL;
> >
> > +        /* Disables upcall and notifies higher layer about the incoming
> > +         * datapath purging. */
> > +        dp_netdev_disable_upcall(dp);
> > +        dp->dp_purge_cb(dp->dp_purge_aux);
> > +
> >          /* Restores the non-pmd. */
> >          dp_netdev_set_nonpmd(dp);
> >          /* Restores all pmd threads. */
> >          dp_netdev_reset_pmd_threads(dp);
> > +
> > +        /* Enables upcall after pmd reconfiguration. */
> > +        dp_netdev_enable_upcall(dp);
> >      }
>
> It is better to enable upcalls before restoring PMD threads to prevent
> dropping of packets.
>
>

Sorry, the comments are misleading, the "dp_netdev_reset_pmd_threads()"
is for recreating all pmd threads (not exactly restoring).  If we move the
"dp_netdev_enable_upcall()" before the function, then upcall will be enabled
before destroying all existing pmd threads, and we will have the same issue
again (the existing pmd threads will try installing flows/creating ukeys
before
getting destroyed).

Also, since recreating pmd threads is considered a major configuration
change and is disruptive, I think it should be okay to resume upcall
handling
right after all new pmd threads are created.


>
> >      return 0;
> > @@ -3419,6 +3434,15 @@ struct dp_netdev_execute_aux {
> >  };
> >
> >  static void
> > +dpif_netdev_register_dp_purge_cb(struct dpif *dpif, dp_purge_callback
> *cb,
> > +                                 void *aux)
> > +{
> > +    struct dp_netdev *dp = get_dp_netdev(dpif);
> > +    dp->dp_purge_aux = aux;
> > +    dp->dp_purge_cb = cb;
> > +}
> > +
> > +static void
> >  dpif_netdev_register_upcall_cb(struct dpif *dpif, upcall_callback *cb,
> >                                 void *aux)
> >  {
> > @@ -3665,6 +3689,7 @@ const struct dpif_class dpif_netdev_class = {
> >      NULL,                       /* recv */
> >      NULL,                       /* recv_wait */
> >      NULL,                       /* recv_purge */
> > +    dpif_netdev_register_dp_purge_cb,
> >      dpif_netdev_register_upcall_cb,
> >      dpif_netdev_enable_upcall,
> >      dpif_netdev_disable_upcall,
> > diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c
> > index 8884a9f..f8f3092 100644
> > --- a/lib/dpif-netlink.c
> > +++ b/lib/dpif-netlink.c
> > @@ -2314,6 +2314,7 @@ const struct dpif_class dpif_netlink_class = {
> >      dpif_netlink_recv,
> >      dpif_netlink_recv_wait,
> >      dpif_netlink_recv_purge,
> > +    NULL,                       /* register_dp_purge_cb */
> >      NULL,                       /* register_upcall_cb */
> >      NULL,                       /* enable_upcall */
> >      NULL,                       /* disable_upcall */
> > diff --git a/lib/dpif-provider.h b/lib/dpif-provider.h
> > index 28ea86f..8f2690f 100644
> > --- a/lib/dpif-provider.h
> > +++ b/lib/dpif-provider.h
> > @@ -361,13 +361,22 @@ struct dpif_class {
> >       * return. */
> >      void (*recv_purge)(struct dpif *dpif);
> >
> > +    /* When 'dpif' is about to purge the datapath, the higher layer may
> want
> > +     * to be notified so that it could try reacting accordingly (e.g.
> grabbing
> > +     * all flow stats before they are gone).
> > +     *
> > +     * Registers an upcall callback function with 'dpif'.  This is only
> used if
>
> double 'if' here too.
>
>
Thx, fixed it,



> > +     * if 'dpif' needs to notify the purging of datapath.  'aux' is
> passed to
> > +     * the callback on invocation. */
> > +    void (*register_dp_purge_cb)(struct dpif *, dp_purge_callback *,
> void *aux);
> > +
> >      /* For datapaths that run in userspace (i.e. dpif-netdev), threads
> polling
> >       * for incoming packets can directly call upcall functions instead
> of
> >       * offloading packet processing to separate handler threads.
> Datapaths
> >       * that directly call upcall functions should use the functions
> below to
> >       * to register an upcall function and enable / disable upcalls.
> >       *
> > -     * Registers an upcall callback function with 'dpif'. This is only
> used if
> > +     * Registers an upcall callback function with 'dpif'. This is only
> used
> >       * if 'dpif' directly executes upcall functions. 'aux' is passed to
> the
> >       * callback on invocation. */
> >      void (*register_upcall_cb)(struct dpif *, upcall_callback *, void
> *aux);
> > diff --git a/lib/dpif.c b/lib/dpif.c
> > index 6e26f30..9a67a24 100644
> > --- a/lib/dpif.c
> > +++ b/lib/dpif.c
> > @@ -1346,6 +1346,14 @@ dpif_handlers_set(struct dpif *dpif, uint32_t
> n_handlers)
> >  }
> >
> >  void
> > +dpif_register_dp_purge_cb(struct dpif *dpif, dp_purge_callback *cb,
> void *aux)
> > +{
> > +    if (dpif->dpif_class->register_dp_purge_cb) {
> > +        dpif->dpif_class->register_dp_purge_cb(dpif, cb, aux);
> > +    }
> > +}
> > +
> > +void
> >  dpif_register_upcall_cb(struct dpif *dpif, upcall_callback *cb, void
> *aux)
> >  {
> >      if (dpif->dpif_class->register_upcall_cb) {
> > diff --git a/lib/dpif.h b/lib/dpif.h
> > index ea9caf8..dca5d00 100644
> > --- a/lib/dpif.h
> > +++ b/lib/dpif.h
> > @@ -787,6 +787,18 @@ struct dpif_upcall {
> >      struct nlattr *actions;    /* Argument to
> OVS_ACTION_ATTR_USERSPACE. */
> >  };
> >
> > +/* A callback to notify higher layer of dpif about to be purged, so that
> > + * higher layer could try reacting to this (e.g. grabbing all flow stats
> > + * before they are gone).  This function is currently implemented only
> by
> > + * dpif-netdev.
> > + *
> > + * The caller only needs to provide the 'aux' pointer passed down by
> higher
> > + * layer from the dpif_register_notify_cb() function.
> > + */
> > +typedef void dp_purge_callback(void *aux);
> > +
> > +void dpif_register_dp_purge_cb(struct dpif *, dp_purge_callback *, void
> *aux);
> > +
> >  /* A callback to process an upcall, currently implemented only by
> dpif-netdev.
> >   *
> >   * The caller provides the 'packet' and 'flow' to process, the
> corresponding
> > diff --git a/ofproto/ofproto-dpif-upcall.c
> b/ofproto/ofproto-dpif-upcall.c
> > index 0f2e186..6385abc 100644
> > --- a/ofproto/ofproto-dpif-upcall.c
> > +++ b/ofproto/ofproto-dpif-upcall.c
> > @@ -306,6 +306,7 @@ static int upcall_receive(struct upcall *, const
> struct dpif_backer *,
> >  static void upcall_uninit(struct upcall *);
> >
> >  static upcall_callback upcall_cb;
> > +static dp_purge_callback dp_purge_cb;
> >
> >  static atomic_bool enable_megaflows = ATOMIC_VAR_INIT(true);
> >  static atomic_bool enable_ufid = ATOMIC_VAR_INIT(true);
> > @@ -358,6 +359,7 @@ udpif_create(struct dpif_backer *backer, struct dpif
> *dpif)
> >      }
> >
> >      dpif_register_upcall_cb(dpif, upcall_cb, udpif);
> > +    dpif_register_dp_purge_cb(dpif, dp_purge_cb, udpif);
> >
> >      return udpif;
> >  }
> > @@ -1110,6 +1112,20 @@ out:
> >      return error;
> >  }
> >
> > +/* In reaction to dpif purge, purges all 'ukey's. */
> > +static void
> > +dp_purge_cb(void *aux)
> > +{
> > +    struct udpif *udpif = aux;
> > +    size_t i;
> > +
> > +    for (i = 0; i < udpif->n_revalidators; i++) {
> > +        struct revalidator *revalidator = &udpif->revalidators[i];
> > +
> > +        revalidator_purge(revalidator);
> > +    }
> > +}
> > +
> >  static int
> >  process_upcall(struct udpif *udpif, struct upcall *upcall,
> >                 struct ofpbuf *odp_actions, struct flow_wildcards *wc)
> >
>
> Best regards, Ilya Maximets.
>



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