[ovs-dev] [PATCH v2 1/5] Enable kernel probes and map stream probes onto them

Mark Michelson mmichels at redhat.com
Thu Jun 4 14:43:51 UTC 2020


Hi Anton, a couple of comments in-line below.

On 6/2/20 3:21 AM, anton.ivanov at cambridgegreys.com wrote:
> From: Anton Ivanov <anton.ivanov at cambridgegreys.com>
> 
> 1. Fix probe logic. The stream_or_pstream_needs_probes
> function returning a mix of integer and boolean. As a
> result probes were NOT turned off in a number of cases on
> unix domain sockets and other transports where there
> should be no probing. It now returns -1 (do not know),
> 0 (no probe needed), 1 (definitely needs probes).

In the patch, a return of -1 and a return of 0 are always treated the 
same. I think a simpler fix here would be to change the -1 return in 
stream_or_pstream_needs_probes() to a 0 return instead. This way, the 
code can continue treating a non-zero return as needing probes instead 
of using a magic number comparison.

> 
> 2. Allow delegating probing to keepalive facilities in the
> stream layer if avaialable.
> 
> 3. Provide TCP KEEPALIVE probing at stream layer on supported
> platforms for stream-ssl and stream-tcp.
> 
> Signed-off-by: Anton Ivanov <anton.ivanov at cambridgegreys.com>
> ---
>   lib/jsonrpc.c          | 36 ++++++++++++++++++++++++++++++++--
>   lib/rconn.c            |  2 +-
>   lib/socket-util.c      | 44 ++++++++++++++++++++++++++++++++++++++++++
>   lib/socket-util.h      |  8 ++++++++
>   lib/stream-fd.c        |  9 +++++++++
>   lib/stream-provider.h  |  6 ++++++
>   lib/stream-ssl.c       |  8 ++++++++
>   lib/stream-tcp.c       |  1 +
>   lib/stream-unix.c      |  1 +
>   lib/stream-windows.c   |  1 +
>   lib/stream.c           | 17 ++++++++++++++--
>   lib/stream.h           |  1 +
>   ovsdb/jsonrpc-server.c |  2 +-
>   13 files changed, 130 insertions(+), 6 deletions(-)
> 
> diff --git a/lib/jsonrpc.c b/lib/jsonrpc.c
> index ed748dbde..15e8d3527 100644
> --- a/lib/jsonrpc.c
> +++ b/lib/jsonrpc.c
> @@ -787,6 +787,7 @@ struct jsonrpc_session {
>       int last_error;
>       unsigned int seqno;
>       uint8_t dscp;
> +    int probe_interval;
>   };
>   
>   static void
> @@ -839,6 +840,7 @@ jsonrpc_session_open_multiple(const struct svec *remotes, bool retry)
>       s->seqno = 0;
>       s->dscp = 0;
>       s->last_error = 0;
> +    s->probe_interval = reconnect_get_probe_interval(s->reconnect);
>   
>       const char *name = reconnect_get_name(s->reconnect);
>       if (!pstream_verify_name(name)) {
> @@ -848,8 +850,9 @@ jsonrpc_session_open_multiple(const struct svec *remotes, bool retry)
>           reconnect_set_backoff(s->reconnect, INT_MAX, INT_MAX);
>       }
>   
> -    if (!stream_or_pstream_needs_probes(name)) {
> +    if (stream_or_pstream_needs_probes(name) < 1) {
>           reconnect_set_probe_interval(s->reconnect, 0);
> +        s->probe_interval = 0;
>       }
>   
>       return s;
> @@ -879,6 +882,12 @@ jsonrpc_session_open_unreliably(struct jsonrpc *jsonrpc, uint8_t dscp)
>       s->stream = NULL;
>       s->pstream = NULL;
>       s->seqno = 1;
> +    s->probe_interval = reconnect_get_probe_interval(s->reconnect);
> +
> +    if (stream_or_pstream_needs_probes(reconnect_get_name(s->reconnect)) < 1) {
> +        reconnect_set_probe_interval(s->reconnect, 0);
> +        s->probe_interval = 0;
> +    }
>   
>       return s;
>   }
> @@ -934,6 +943,12 @@ jsonrpc_session_connect(struct jsonrpc_session *s)
>           error = jsonrpc_stream_open(name, &s->stream, s->dscp);
>           if (!error) {
>               reconnect_connecting(s->reconnect, time_msec());
> +            if (stream_set_probe_interval(s->stream, s->probe_interval)) {
> +                /* we have delegated probing to the stream layer */
> +                reconnect_set_probe_interval(s->reconnect, 0);
> +            } else {
> +                reconnect_set_probe_interval(s->reconnect, s->probe_interval);
> +            }
>           } else {
>               s->last_error = error;
>           }
> @@ -967,6 +982,12 @@ jsonrpc_session_run(struct jsonrpc_session *s)
>                   jsonrpc_session_disconnect(s);
>               }
>               reconnect_connected(s->reconnect, time_msec());
> +            if (stream_set_probe_interval(stream, s->probe_interval)) {
> +                /* we have delegated probing to the stream layer */
> +                reconnect_set_probe_interval(s->reconnect, 0);
> +            } else {
> +                reconnect_set_probe_interval(s->reconnect, s->probe_interval);
> +            }
>               s->rpc = jsonrpc_open(stream);
>               s->seqno++;
>           } else if (error != EAGAIN) {
> @@ -1008,6 +1029,12 @@ jsonrpc_session_run(struct jsonrpc_session *s)
>           if (!error) {
>               reconnect_connected(s->reconnect, time_msec());
>               s->rpc = jsonrpc_open(s->stream);
> +            if (stream_set_probe_interval(s->stream, s->probe_interval)) {
> +                /* we have delegated probing to the stream layer */
> +                reconnect_set_probe_interval(s->reconnect, 0);
> +            } else {
> +                reconnect_set_probe_interval(s->reconnect, s->probe_interval);
> +            }
>               s->stream = NULL;
>               s->seqno++;
>           } else if (error != EAGAIN) {
> @@ -1231,7 +1258,12 @@ void
>   jsonrpc_session_set_probe_interval(struct jsonrpc_session *s,
>                                      int probe_interval)
>   {
> -    reconnect_set_probe_interval(s->reconnect, probe_interval);
> +    s->probe_interval = probe_interval;
> +    if (s->stream && s->probe_interval) {
> +        if (!stream_set_probe_interval(s->stream, probe_interval)) {
> +           reconnect_set_probe_interval(s->reconnect, probe_interval);

I might be missing something, but the logic seems a bit off here.

1) If probe_interval is 0, then this doesn't alter probe intervals at 
all. The comment above the function says that a 0 value should disable 
probe intervals.
2) If s->stream is NULL, then this won't alter s->reconnect's 
probe_interval at all. This could be an issue if the intent was to 
lengthen the probe interval or disable it temporarily during downtime.
3) In the case where stream_set_probe_interval succeeds, shouldn't we 
call reconnect_set_probe_interval(s->reconnect, 0)?

> +        }
> +    }
>   }
>   
>   /* Sets the DSCP value used for 's''s connection to 'dscp'.  If this is
> diff --git a/lib/rconn.c b/lib/rconn.c
> index a96b2eb8b..16e7a44d4 100644
> --- a/lib/rconn.c
> +++ b/lib/rconn.c
> @@ -346,7 +346,7 @@ rconn_connect(struct rconn *rc, const char *target, const char *name)
>       rconn_disconnect__(rc);
>       rconn_set_target__(rc, target, name);
>       rc->reliable = true;
> -    if (!stream_or_pstream_needs_probes(target)) {
> +    if (stream_or_pstream_needs_probes(target) < 1) {
>           rc->probe_interval = 0;
>       }
>       reconnect(rc);
> diff --git a/lib/socket-util.c b/lib/socket-util.c
> index 4f1ffecf5..d6d1967f6 100644
> --- a/lib/socket-util.c
> +++ b/lib/socket-util.c
> @@ -114,6 +114,50 @@ setsockopt_tcp_nodelay(int fd)
>       }
>   }
>   
> +#ifdef HAS_KERNEL_KEEPALIVES
> +bool tcp_set_probe_interval(int fd, int probe_interval) {

Is there any way to attempt to make this function atomic? For example, 
we could manage to turn on keepalives, successfully set TCP_KEEPCNT, but 
then fail to set TCP_KEEPIDLE. This would result in a false return, 
which callers currently interpret to mean a complete failure to set 
keepalives. However, in actuality they've been enabled but just not with 
the configured probe_interval. This could lead to some odd debugging 
scenarios.

Also, there should be a special case in this function where if 
probe_interval is 0, it disables keepalives. I have no idea what happens 
if you turn on keepalives but set TCP_KEEPIDLE and TCP_KEEPINTVL to 0.

> +    int on = 1;
> +    int retval;
> +    int value;
> +
> +    on = 1;
> +    retval = setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof on);
> +    if (retval) {
> +        retval = sock_errno();
> +        VLOG_DBG("setsockopt(SO_KEEPALIVE): %s", sock_strerror(retval));
> +        return false;
> +    }
> +    value = 2;
> +    retval = setsockopt(fd,
> +            IPPROTO_TCP, TCP_KEEPCNT, &value, sizeof value);
> +    if (retval) {
> +        retval = sock_errno();
> +        VLOG_DBG("setsockopt(TCP_KEEPCNT): %s", sock_strerror(retval));
> +        return false;
> +    }
> +    value = probe_interval;
> +    retval = setsockopt(fd,
> +            IPPROTO_TCP, TCP_KEEPIDLE, &value, sizeof value);
> +    if (retval) {
> +        retval = sock_errno();
> +        VLOG_DBG("setsockopt(TCP_KEEPIDLE): %s", sock_strerror(retval));
> +        return false;
> +    }
> +    value = probe_interval;
> +    retval = setsockopt(fd,
> +            IPPROTO_TCP, TCP_KEEPINTVL, &value, sizeof value);
> +    if (retval) {
> +        retval = sock_errno();
> +        VLOG_DBG("setsockopt(SO_KEEPALIVE): %s", sock_strerror(retval));
> +        return false;
> +    }
> +    return true;
> +#else
> +bool tcp_set_probe_interval(int fd OVS_UNUSED, int probe_interval OVS_UNUSED) {
> +    return false;
> +#endif
> +}
> +
>   /* Sets the DSCP value of socket 'fd' to 'dscp', which must be 63 or less.
>    * 'family' must indicate the socket's address family (AF_INET or AF_INET6, to
>    * do anything useful). */
> diff --git a/lib/socket-util.h b/lib/socket-util.h
> index 9ccb7d4cc..2439e2f78 100644
> --- a/lib/socket-util.h
> +++ b/lib/socket-util.h
> @@ -27,6 +27,7 @@
>   #include "openvswitch/types.h"
>   #include <netinet/in_systm.h>
>   #include <netinet/ip.h>
> +#include <netinet/tcp.h>
>   
>   struct ds;
>   
> @@ -181,4 +182,11 @@ static inline int sock_errno(void)
>   #endif
>   }
>   
> +#if defined (SO_KEEPALIVE) && defined (TCP_KEEPCNT) && \
> +    defined (TCP_KEEPIDLE) && defined (TCP_KEEPINTVL)
> +#define HAS_KERNEL_KEEPALIVES 1
> +#endif
> +
> +bool tcp_set_probe_interval(int fd, int probe_interval);
> +
>   #endif /* socket-util.h */
> diff --git a/lib/stream-fd.c b/lib/stream-fd.c
> index 46ee7ae27..30622929b 100644
> --- a/lib/stream-fd.c
> +++ b/lib/stream-fd.c
> @@ -162,6 +162,14 @@ fd_wait(struct stream *stream, enum stream_wait_type wait)
>       }
>   }
>   
> +static bool fd_set_probe_interval(struct stream *stream, int probe_interval) {
> +    struct stream_fd *sf = stream_fd_cast(stream);
> +
> +    return tcp_set_probe_interval(sf->fd, probe_interval);
> +}
> +
> +
> +
>   static const struct stream_class stream_fd_class = {
>       "fd",                       /* name */
>       false,                      /* needs_probes */
> @@ -173,6 +181,7 @@ static const struct stream_class stream_fd_class = {
>       NULL,                       /* run */
>       NULL,                       /* run_wait */
>       fd_wait,                    /* wait */
> +    fd_set_probe_interval,      /* set_probe_interval */
>   };
>   

>   /* Passive file descriptor stream. */
> diff --git a/lib/stream-provider.h b/lib/stream-provider.h
> index 75f4f059b..6c28cb50b 100644
> --- a/lib/stream-provider.h
> +++ b/lib/stream-provider.h
> @@ -124,6 +124,12 @@ struct stream_class {
>       /* Arranges for the poll loop to wake up when 'stream' is ready to take an
>        * action of the given 'type'. */
>       void (*wait)(struct stream *stream, enum stream_wait_type type);
> +    /* Sets low level keepalives if supported
> +     *
> +     *     If successful returns true
> +     *
> +     */
> +    bool (*set_probe_interval)(struct stream *stream, int probe_interval);
>   };
>   

>   /* Passive listener for incoming stream connections.
> diff --git a/lib/stream-ssl.c b/lib/stream-ssl.c
> index 078fcbc3a..575c55f5b 100644
> --- a/lib/stream-ssl.c
> +++ b/lib/stream-ssl.c
> @@ -789,6 +789,13 @@ ssl_run(struct stream *stream)
>       }
>   }
>   
> +static bool ssl_set_probe_interval(struct stream *stream, int probe_interval) {
> +    struct ssl_stream *sslv = ssl_stream_cast(stream);
> +
> +    return tcp_set_probe_interval(sslv->fd, probe_interval);
> +}
> +
> +
>   static void
>   ssl_run_wait(struct stream *stream)
>   {
> @@ -861,6 +868,7 @@ const struct stream_class ssl_stream_class = {
>       ssl_run,                    /* run */
>       ssl_run_wait,               /* run_wait */
>       ssl_wait,                   /* wait */
> +    ssl_set_probe_interval,     /* set_probe_interval */
>   };
>   

>   /* Passive SSL. */
> diff --git a/lib/stream-tcp.c b/lib/stream-tcp.c
> index e8dc2bfaa..67c912105 100644
> --- a/lib/stream-tcp.c
> +++ b/lib/stream-tcp.c
> @@ -73,6 +73,7 @@ const struct stream_class tcp_stream_class = {
>       NULL,                       /* run */
>       NULL,                       /* run_wait */
>       NULL,                       /* wait */
> +    NULL,
>   };
>   

>   /* Passive TCP. */
> diff --git a/lib/stream-unix.c b/lib/stream-unix.c
> index d265efb83..2322df955 100644
> --- a/lib/stream-unix.c
> +++ b/lib/stream-unix.c
> @@ -73,6 +73,7 @@ const struct stream_class unix_stream_class = {
>       NULL,                       /* run */
>       NULL,                       /* run_wait */
>       NULL,                       /* wait */
> +    NULL,
>   };
>   

>   /* Passive UNIX socket. */
> diff --git a/lib/stream-windows.c b/lib/stream-windows.c
> index 5c4c55e5d..836112f75 100644
> --- a/lib/stream-windows.c
> +++ b/lib/stream-windows.c
> @@ -374,6 +374,7 @@ const struct stream_class windows_stream_class = {
>       NULL,                       /* run */
>       NULL,                       /* run_wait */
>       windows_wait,               /* wait */
> +    NULL,
>   };
>   
>   struct pwindows_pstream
> diff --git a/lib/stream.c b/lib/stream.c
> index e246b3773..f0b16fb4f 100644
> --- a/lib/stream.c
> +++ b/lib/stream.c
> @@ -430,6 +430,19 @@ stream_wait(struct stream *stream, enum stream_wait_type wait)
>       (stream->class->wait)(stream, wait);
>   }
>   
> +
> +bool stream_set_probe_interval(struct stream *stream, int probe_interval) {
> +    if (! stream->class->needs_probes) {
> +        return true;
> +    }
> +    if (probe_interval && stream->class->set_probe_interval) {
> +        return (stream->class->set_probe_interval)(
> +                stream, probe_interval / 1000);
> +    }
> +    return false;
> +}
> +
> +
>   void
>   stream_connect_wait(struct stream *stream)
>   {
> @@ -509,9 +522,9 @@ stream_or_pstream_needs_probes(const char *name)
>       const struct stream_class *class;
>   
>       if (!stream_lookup_class(name, &class)) {
> -        return class->needs_probes;
> +        return class->needs_probes ? 1 : 0;
>       } else if (!pstream_lookup_class(name, &pclass)) {
> -        return pclass->needs_probes;
> +        return pclass->needs_probes ? 1 : 0;
>       } else {
>           return -1;
>       }
> diff --git a/lib/stream.h b/lib/stream.h
> index 77bffa498..e343f75a5 100644
> --- a/lib/stream.h
> +++ b/lib/stream.h
> @@ -40,6 +40,7 @@ const char *stream_get_name(const struct stream *);
>   int stream_connect(struct stream *);
>   int stream_recv(struct stream *, void *buffer, size_t n);
>   int stream_send(struct stream *, const void *buffer, size_t n);
> +bool stream_set_probe_interval(struct stream *, int probe_interval);
>   
>   void stream_run(struct stream *);
>   void stream_run_wait(struct stream *);
> diff --git a/ovsdb/jsonrpc-server.c b/ovsdb/jsonrpc-server.c
> index 4e2dfc3d7..fe8ffc317 100644
> --- a/ovsdb/jsonrpc-server.c
> +++ b/ovsdb/jsonrpc-server.c
> @@ -212,7 +212,7 @@ ovsdb_jsonrpc_default_options(const char *target)
>   {
>       struct ovsdb_jsonrpc_options *options = xzalloc(sizeof *options);
>       options->max_backoff = RECONNECT_DEFAULT_MAX_BACKOFF;
> -    options->probe_interval = (stream_or_pstream_needs_probes(target)
> +    options->probe_interval = (stream_or_pstream_needs_probes(target) < 1
>                                  ? RECONNECT_DEFAULT_PROBE_INTERVAL
>                                  : 0);
>       return options;
> 



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