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Re: [libvirt] [PATCH V4 2/5] remote handler for virDomainGetCPUStats()



On 01/27/2012 11:21 PM, KAMEZAWA Hiroyuki wrote:
> remote protocol driver for virDomainGetCPUStats()
> 
> Note:
> Unlike other users of virTypedParameter with RPC, this interface
> can return zero-filled entries because the interface assumes
> 2 dimentional array. Then, the function has its own serialize/deserialize

s/dimentional/dimensional/

> routine.
> 
>  daemon/remote.c              |  146 +++++++++++++++++++++++++++++++++++++++++++
>  src/remote/remote_driver.c   |  117 ++++++++++++++++++++++++++++++++++
>  src/remote/remote_protocol.x |   22 ++++++
>  src/remote_protocol-structs  |   15 ++++
> ---
>  daemon/remote.c              |  147 ++++++++++++++++++++++++++++++++++++++++++
>  src/remote/remote_driver.c   |  117 +++++++++++++++++++++++++++++++++
>  src/remote/remote_protocol.x |   22 ++++++-
>  src/remote_protocol-structs  |   15 +++

Odd that the diffstat listed twice.

I'm going to reorder my review, to start with the .x file.

> diff --git a/src/remote/remote_protocol.x b/src/remote/remote_protocol.x
> index 0f354bb..205aeeb 100644
> --- a/src/remote/remote_protocol.x
> +++ b/src/remote/remote_protocol.x
> @@ -208,6 +208,12 @@ const REMOTE_DOMAIN_SEND_KEY_MAX = 16;
>   */
>  const REMOTE_DOMAIN_INTERFACE_PARAMETERS_MAX = 16;
>
> +/*
> + * Upper limit on list of (real) cpu parameters
> + * nparams(<=16) * ncpus(<=128) <= 2048.
> + */
> +const REMOTE_DOMAIN_GET_CPU_STATS_MAX = 2048;

We should enforce the two limits independently, which means we also need
two smaller constants (it's a shame that rpcgen doesn't allow products
when computing a constant, but we can document how we arrive at various
numbers).  We can reuse VIR_NODE_CPU_STATS_MAX for one of the two limits.

> +
>  /* UUID.  VIR_UUID_BUFLEN definition comes from libvirt.h */
>  typedef opaque remote_uuid[VIR_UUID_BUFLEN];
>
> @@ -1149,6 +1155,19 @@ struct remote_domain_get_block_io_tune_ret {
>      int nparams;
>  };
>
> +struct remote_domain_get_cpu_stats_args {
> +    remote_nonnull_domain dom;
> +    unsigned int nparams;
> +    int          start_cpu;
> +    unsigned int ncpus;
> +    unsigned int flags;
> +};
> +
> +struct remote_domain_get_cpu_stats_ret {
> +    remote_typed_param params<REMOTE_DOMAIN_GET_CPU_STATS_MAX>;
> +    int nparams;
> +};

Looks good.

> +
>  /* Network calls: */
>
>  struct remote_num_of_networks_ret {
> @@ -2667,7 +2686,8 @@ enum remote_procedure {
>      REMOTE_PROC_DOMAIN_SET_INTERFACE_PARAMETERS = 256, /* autogen
autogen */
>      REMOTE_PROC_DOMAIN_GET_INTERFACE_PARAMETERS = 257, /* skipgen
skipgen */
>      REMOTE_PROC_DOMAIN_SHUTDOWN_FLAGS = 258, /* autogen autogen */
> -    REMOTE_PROC_STORAGE_VOL_WIPE_PATTERN = 259 /* autogen autogen */
> +    REMOTE_PROC_STORAGE_VOL_WIPE_PATTERN = 259, /* autogen autogen */
> +    REMOTE_PROC_DOMAIN_GET_CPU_STATS = 260 /* skipgen skipgen */

Trivial conflict resolution.


> +static int
> +remoteDispatchDomainGetCPUStats(virNetServerPtr server ATTRIBUTE_UNUSED,
> +                                virNetServerClientPtr client ATTRIBUTE_UNUSED,
> +                                virNetMessagePtr hdr ATTRIBUTE_UNUSED,
> +                                virNetMessageErrorPtr rerr,
> +                                remote_domain_get_cpu_stats_args *args,
> +                                remote_domain_get_cpu_stats_ret *ret)
> +{
> +    virDomainPtr dom = NULL;
> +    struct daemonClientPrivate *priv;
> +    virTypedParameterPtr params = NULL;
> +    remote_typed_param *info = NULL;
> +    int cpu, idx, src, dest;
> +    int rv = -1;
> +    unsigned int return_size = 0;
> +    int percpu_len = 0;
> +
> +    priv = virNetServerClientGetPrivateData(client);
> +    if (!priv->conn) {
> +        virNetError(VIR_ERR_INTERNAL_ERROR, "%s", _("connection not open"));
> +        goto cleanup;
> +    }
> +
> +    /*
> +     * nparams * ncpus should be smaller than
> +     * REMOTE_DOMAIN_GET_CPU_STATS_MAX but nparams
> +     * and ncpus are limited by API. check it.
> +     */
> +    if (args->nparams > 16) {
> +        virNetError(VIR_ERR_INTERNAL_ERROR, "%s", _("nparams too large"));
> +        goto cleanup;
> +    }
> +    if (args->ncpus > 128) {

Use the constants from the .x file, rather than open-coding things.
Oops, I just realized that I mentioned that libvirt.c should not have a
length check, but then I forgot to delete it.  Meanwhile, even if
libvirt.c does not have a length check, it still needs to have a
multiplication overflow check.

> +    /*
> +     * Here, we return values based on the real param size returned by
> +     * a driver rather than the passed one. RPC Client stub should decode
> +     * it to fit callar's expectation.

s/callar/caller/

> +     *
> +     * If cpu ID is sparse, The whole array for some cpu IDs will be
> +     * zero-cleared. This doesn't meet to remoteSerializeTypedParameters()
> +     * and we do serialization by ourselves.

We can still use remoteSerializeTypedParameters; we just have to teach
it to skip zero entries like it already can skip string entries.

Oh, I just realized that to support string entries, we have to support a
flags of VIR_TYPED_PARAM_STRING_OKAY.

> +success:
> +    rv = 0;
> +    ret->params.params_len = return_size;
> +    ret->params.params_val = info;
> +    ret->nparams = percpu_len;
> +cleanup:
> +    if (rv < 0) {
> +         virNetMessageSaveError(rerr);
> +         if (info) {

Cleanup is a lot simpler if we let the existing serialization skip zero
entries.

> +++ b/src/remote/remote_driver.c
> @@ -2305,6 +2305,122 @@ done:
>      return rv;
>  }
>  
> +static int remoteDomainGetCPUStats(virDomainPtr domain,
> +                                   virTypedParameterPtr params,
> +                                   unsigned int nparams,
> +                                   int start_cpu,
> +                                   unsigned int ncpus,
> +                                   unsigned int flags)
> +{
> +    struct private_data *priv = domain->conn->privateData;
> +    remote_domain_get_cpu_stats_args args;
> +    remote_domain_get_cpu_stats_ret ret;
> +    remote_typed_param *info;
> +    int rv = -1;
> +    int cpu, idx, src, dest;
> +
> +    remoteDriverLock(priv);
> +
> +    make_nonnull_domain(&args.dom, domain);
> +    args.nparams = nparams;
> +    args.start_cpu = start_cpu;
> +    args.ncpus = ncpus;
> +    args.flags = flags;
> +
> +    memset(&ret, 0, sizeof(ret));

This side needs to validate incoming parameters before sending over the
wire.  Hmm, remoteNodeGetCPUStats needs to do likewise.

> +
> +    if (call(domain->conn, priv, 0, REMOTE_PROC_DOMAIN_GET_CPU_STATS,
> +             (xdrproc_t) xdr_remote_domain_get_cpu_stats_args,
> +             (char *) &args,
> +             (xdrproc_t) xdr_remote_domain_get_cpu_stats_ret,
> +             (char *) &ret) == -1)
> +        goto done;
> +
> +    if (nparams == 0) {
> +        rv = ret.nparams;
> +        goto cleanup;
> +    }
> +    /*
> +     * the returned arrray's size is not same to nparams * ncpus. And
> +     * if cpu ID is not contiguous, all-zero entries can be found.
> +     */
> +    memset(params, 0, sizeof(virTypedParameter) * nparams * ncpus);

I prefer sizeof(expr) over sizeof(type), in case expr ever changes types.

> +
> +    /* Here, ret.nparams is always smaller than nparams */
> +    info = ret.params.params_val;
> +
> +    for (cpu = 0; cpu < ncpus; ++cpu) {
> +        for (idx = 0; idx < ret.nparams; ++idx) {
> +            src = cpu * ret.nparams + idx;
> +            dest = cpu * nparams + idx;
> +
> +            if (info[src].value.type == 0) /* skip zeroed ones */
> +                continue;

Again, open coding things is not nice.  If we write the server to never
send zero entries (which is a good thing - less data over the wire),
then the client needs to re-create zero entries by calling
deserialization in a loop - deserialize ret.nparams entries at every
nparams slot.

> +
> +    rv = ret.nparams;
> +cleanup:
> +    if (rv < 0) {
> +        int max = nparams * ncpus;
> +        int i;
> +
> +        for (i = 0; i < max; i++) {
> +            if (params[i].type == VIR_TYPED_PARAM_STRING)
> +                VIR_FREE(params[i].value.s);

Potential free of bogus memory if anything can reach cleanup with rv < 0
but before we sanitized the contents of params.

Here's what I'm squashing in:


diff --git i/daemon/remote.c w/daemon/remote.c
index 15857a8..cb8423a 100644
--- i/daemon/remote.c
+++ w/daemon/remote.c
@@ -704,8 +704,11 @@ remoteSerializeTypedParameters(virTypedParameterPtr
params,
     }

     for (i = 0, j = 0; i < nparams; ++i) {
-        if (!(flags & VIR_TYPED_PARAM_STRING_OKAY) &&
-            params[i].type == VIR_TYPED_PARAM_STRING) {
+        /* virDomainGetCPUStats can return a sparse array; also, we
+         * can't pass back strings to older clients.  */
+        if (!params[i].type ||
+            (!(flags & VIR_TYPED_PARAM_STRING_OKAY) &&
+             params[i].type == VIR_TYPED_PARAM_STRING)) {
             --*ret_params_len;
             continue;
         }
@@ -3534,10 +3537,7 @@ remoteDispatchDomainGetCPUStats(virNetServerPtr
server ATTRIBUTE_UNUSED,
     virDomainPtr dom = NULL;
     struct daemonClientPrivate *priv;
     virTypedParameterPtr params = NULL;
-    remote_typed_param *info = NULL;
-    int cpu, idx, src, dest;
     int rv = -1;
-    unsigned int return_size = 0;
     int percpu_len = 0;

     priv = virNetServerClientGetPrivateData(client);
@@ -3546,128 +3546,53 @@ remoteDispatchDomainGetCPUStats(virNetServerPtr
server ATTRIBUTE_UNUSED,
         goto cleanup;
     }

-    /*
-     * nparams * ncpus should be smaller than
-     * REMOTE_DOMAIN_GET_CPU_STATS_MAX but nparams
-     * and ncpus are limited by API. check it.
-     */
-    if (args->nparams > 16) {
+    if (args->nparams > REMOTE_NODE_CPU_STATS_MAX) {
         virNetError(VIR_ERR_INTERNAL_ERROR, "%s", _("nparams too large"));
         goto cleanup;
     }
-    if (args->ncpus > 128) {
+    if (args->ncpus > REMOTE_DOMAIN_GET_CPU_STATS_NCPUS_MAX) {
         virNetError(VIR_ERR_INTERNAL_ERROR, "%s", _("ncpus too large"));
         goto cleanup;
     }

-    if (args->nparams > 0) {
-        if (VIR_ALLOC_N(params, args->ncpus * args->nparams) < 0)
-            goto no_memory;
+    if (args->nparams > 0 &&
+        VIR_ALLOC_N(params, args->ncpus * args->nparams) < 0) {
+        virReportOOMError();
+        goto cleanup;
     }

     if (!(dom = get_nonnull_domain(priv->conn, args->dom)))
         goto cleanup;

     percpu_len = virDomainGetCPUStats(dom, params, args->nparams,
-                                args->start_cpu, args->ncpus, args->flags);
+                                      args->start_cpu, args->ncpus,
+                                      args->flags);
     if (percpu_len < 0)
         goto cleanup;
-    /* If nparams == 0, the function returns a sigle value */
+    /* If nparams == 0, the function returns a single value */
     if (args->nparams == 0)
         goto success;

-    /*
-     * Here, we return values based on the real param size returned by
-     * a driver rather than the passed one. RPC Client stub should decode
-     * it to fit callar's expectation.
-     *
-     * If cpu ID is sparse, The whole array for some cpu IDs will be
-     * zero-cleared. This doesn't meet to remoteSerializeTypedParameters()
-     * and we do serialization by ourselves.
-     */
-    return_size = percpu_len * args->ncpus;
-    if (VIR_ALLOC_N(info, return_size) < 0)
-        goto no_memory;
+    if (remoteSerializeTypedParameters(params, args->nparams * args->ncpus,
+                                       &ret->params.params_val,
+                                       &ret->params.params_len,
+                                       args->flags) < 0)
+        goto cleanup;
+
+    percpu_len = ret->params.params_len / args->ncpus;

-    for (cpu = 0; cpu < args->ncpus; ++cpu) {
-        for (idx = 0; idx < percpu_len; ++idx) {
-            src = cpu * args->nparams + idx;
-            dest = cpu * percpu_len + idx;
-
-            /* If CPU ID is discontiguous, this can happen */
-            if (params[src].type == 0)
-                continue;
-
-            info[dest].field = strdup(params[src].field);
-            if (info[dest].field == NULL)
-                goto no_memory;
-
-            info[dest].value.type = params[src].type;
-
-            switch (params[src].type) {
-            case VIR_TYPED_PARAM_INT:
-                info[dest].value.remote_typed_param_value_u.i =
-                    params[src].value.i;
-                break;
-            case VIR_TYPED_PARAM_UINT:
-                info[dest].value.remote_typed_param_value_u.ui =
-                    params[src].value.ui;
-                break;
-            case VIR_TYPED_PARAM_LLONG:
-                info[dest].value.remote_typed_param_value_u.l =
-                    params[src].value.l;
-                break;
-            case VIR_TYPED_PARAM_ULLONG:
-                info[dest].value.remote_typed_param_value_u.ul =
-                    params[src].value.ul;
-                break;
-            case VIR_TYPED_PARAM_DOUBLE:
-                info[dest].value.remote_typed_param_value_u.d =
-                    params[src].value.d;
-                break;
-            case VIR_TYPED_PARAM_BOOLEAN:
-                info[dest].value.remote_typed_param_value_u.b =
-                    params[src].value.b;
-                break;
-            case VIR_TYPED_PARAM_STRING:
-                info[dest].value.remote_typed_param_value_u.s =
-                    strdup(params[src].value.s);
-                if (info[dest].value.remote_typed_param_value_u.s == NULL)
-                    goto no_memory;
-                break;
-            default:
-                virNetError(VIR_ERR_RPC, _("unknown parameter type: %d"),
-                            params[src].type);
-                goto cleanup;
-            }
-        }
-    }
 success:
     rv = 0;
-    ret->params.params_len = return_size;
-    ret->params.params_val = info;
     ret->nparams = percpu_len;
+
 cleanup:
-    if (rv < 0) {
+    if (rv < 0)
          virNetMessageSaveError(rerr);
-         if (info) {
-             int i;
-             for (i = 0; i < return_size; i++) {
-                 VIR_FREE(info[i].field);
-                 if (info[i].value.type == VIR_TYPED_PARAM_STRING)
-                     VIR_FREE(info[i].value.remote_typed_param_value_u.s);
-             }
-             VIR_FREE(info);
-         }
-    }
     virTypedParameterArrayClear(params, args->ncpus * args->nparams);
     VIR_FREE(params);
     if (dom)
         virDomainFree(dom);
     return rv;
-no_memory:
-    virReportOOMError();
-    goto cleanup;
 }

 /*----- Helpers. -----*/
diff --git i/src/libvirt.c w/src/libvirt.c
index 7060f5a..e702a34 100644
--- i/src/libvirt.c
+++ w/src/libvirt.c
@@ -18162,7 +18162,7 @@ error:
  * @nparams: number of parameters per cpu
  * @start_cpu: which cpu to start with, or -1 for summary
  * @ncpus: how many cpus to query
- * @flags: extra flags; not used yet, so callers should always pass 0
+ * @flags: bitwise-OR of virTypedParameterFlags
  *
  * Get statistics relating to CPU usage attributable to a single
  * domain (in contrast to the statistics returned by
@@ -18251,20 +18251,19 @@ int virDomainGetCPUStats(virDomainPtr domain,
      * if start_cpu is -1, ncpus must be 1
      * params == NULL must match nparams == 0
      * ncpus must be non-zero unless params == NULL
+     * nparams * ncpus must not overflow (RPC may restrict it even more)
      */
     if (start_cpu < -1 ||
         (start_cpu == -1 && ncpus != 1) ||
         ((params == NULL) != (nparams == 0)) ||
-        (ncpus == 0 && params != NULL)) {
-        virLibDomainError(VIR_ERR_INVALID_ARG, __FUNCTION__);
-        goto error;
-    }
-
-    /* remote protocol doesn't welcome big args in one shot */
-    if ((nparams > 16) || (ncpus > 128)) {
+        (ncpus == 0 && params != NULL) ||
+        ncpus < UINT_MAX / nparams) {
         virLibDomainError(VIR_ERR_INVALID_ARG, __FUNCTION__);
         goto error;
     }
+    if (VIR_DRV_SUPPORTS_FEATURE(domain->conn->driver, domain->conn,
+                                 VIR_DRV_FEATURE_TYPED_PARAM_STRING))
+        flags |= VIR_TYPED_PARAM_STRING_OKAY;

     if (conn->driver->domainGetCPUStats) {
         int ret;
diff --git i/src/remote/remote_driver.c w/src/remote/remote_driver.c
index a3ca63e..2312cf9 100644
--- i/src/remote/remote_driver.c
+++ w/src/remote/remote_driver.c
@@ -2,7 +2,7 @@
  * remote_driver.c: driver to provide access to libvirtd running
  *   on a remote machine
  *
- * Copyright (C) 2007-2011 Red Hat, Inc.
+ * Copyright (C) 2007-2012 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -2315,12 +2315,24 @@ static int remoteDomainGetCPUStats(virDomainPtr
domain,
     struct private_data *priv = domain->conn->privateData;
     remote_domain_get_cpu_stats_args args;
     remote_domain_get_cpu_stats_ret ret;
-    remote_typed_param *info;
     int rv = -1;
-    int cpu, idx, src, dest;
+    int cpu;

     remoteDriverLock(priv);

+    if (nparams > REMOTE_NODE_CPU_STATS_MAX) {
+        remoteError(VIR_ERR_RPC,
+                    _("nparams count exceeds maximum: %u > %u"),
+                    nparams, REMOTE_NODE_CPU_STATS_MAX);
+        goto done;
+    }
+    if (ncpus > REMOTE_DOMAIN_GET_CPU_STATS_NCPUS_MAX) {
+        remoteError(VIR_ERR_RPC,
+                    _("ncpus count exceeds maximum: %u > %u"),
+                    ncpus, REMOTE_DOMAIN_GET_CPU_STATS_NCPUS_MAX);
+        goto done;
+    }
+
     make_nonnull_domain(&args.dom, domain);
     args.nparams = nparams;
     args.start_cpu = start_cpu;
@@ -2336,67 +2348,38 @@ static int remoteDomainGetCPUStats(virDomainPtr
domain,
              (char *) &ret) == -1)
         goto done;

+    /* Check the length of the returned list carefully. */
+    if (ret.params.params_len > nparams * ncpus ||
+        (ret.params.params_len &&
+         ret.nparams * ncpus != ret.params.params_len)) {
+        remoteError(VIR_ERR_RPC, "%s",
+                    _("remoteDomainGetCPUStats: "
+                      "returned number of stats exceeds limit"));
+        memset(params, 0, sizeof(*params) * nparams * ncpus);
+        goto cleanup;
+    }
+
+    /* Handle the case when the caller does not know the number of stats
+     * and is asking for the number of stats supported
+     */
     if (nparams == 0) {
         rv = ret.nparams;
         goto cleanup;
     }
-    /*
-     * the returned arrray's size is not same to nparams * ncpus. And
-     * if cpu ID is not contiguous, all-zero entries can be found.
+
+    /* The remote side did not send back any zero entries, so we have
+     * to expand things back into a possibly sparse array.
      */
-    memset(params, 0, sizeof(virTypedParameter) * nparams * ncpus);
-
-    /* Here, ret.nparams is always smaller than nparams */
-    info = ret.params.params_val;
-
-    for (cpu = 0; cpu < ncpus; ++cpu) {
-        for (idx = 0; idx < ret.nparams; ++idx) {
-            src = cpu * ret.nparams + idx;
-            dest = cpu * nparams + idx;
-
-            if (info[src].value.type == 0) /* skip zeroed ones */
-                continue;
-
-            params[dest].type = info[src].value.type;
-            strcpy(params[dest].field, info[src].field);
-
-            switch (params[dest].type) {
-            case VIR_TYPED_PARAM_INT:
-                params[dest].value.i =
-                    info[src].value.remote_typed_param_value_u.i;
-                break;
-            case VIR_TYPED_PARAM_UINT:
-                params[dest].value.ui =
-                    info[src].value.remote_typed_param_value_u.ui;
-                break;
-            case VIR_TYPED_PARAM_LLONG:
-                params[dest].value.l =
-                    info[src].value.remote_typed_param_value_u.l;
-                break;
-            case VIR_TYPED_PARAM_ULLONG:
-                params[dest].value.ul =
-                    info[src].value.remote_typed_param_value_u.ul;
-                break;
-            case VIR_TYPED_PARAM_DOUBLE:
-                params[dest].value.d =
-                    info[src].value.remote_typed_param_value_u.d;
-                break;
-            case VIR_TYPED_PARAM_BOOLEAN:
-                params[dest].value.b =
-                    info[src].value.remote_typed_param_value_u.b;
-                break;
-            case VIR_TYPED_PARAM_STRING:
-                params[dest].value.s =
-                    strdup(info[src].value.remote_typed_param_value_u.s);
-                if (params[dest].value.s == NULL)
-                    goto out_of_memory;
-                break;
-            default:
-                remoteError(VIR_ERR_RPC, _("unknown parameter type: %d"),
-                            params[dest].type);
-                goto cleanup;
-            }
-        }
+    memset(params, 0, sizeof(*params) * nparams * ncpus);
+    for (cpu = 0; cpu < ncpus; cpu++) {
+        int tmp = nparams;
+        remote_typed_param *stride = &ret.params.params_val[cpu *
ret.nparams];
+
+        if (remoteDeserializeTypedParameters(stride, ret.nparams,
+                                             REMOTE_NODE_CPU_STATS_MAX,
+                                             &params[cpu * nparams],
+                                             &tmp) < 0)
+            goto cleanup;
     }

     rv = ret.nparams;
@@ -2415,9 +2398,6 @@ cleanup:
 done:
     remoteDriverUnlock(priv);
     return rv;
-out_of_memory:
-    virReportOOMError();
-    goto cleanup;
 }


diff --git i/src/remote/remote_protocol.x w/src/remote/remote_protocol.x
index 0bd399c..b58925a 100644
--- i/src/remote/remote_protocol.x
+++ w/src/remote/remote_protocol.x
@@ -209,8 +209,13 @@ const REMOTE_DOMAIN_SEND_KEY_MAX = 16;
 const REMOTE_DOMAIN_INTERFACE_PARAMETERS_MAX = 16;

 /*
- * Upper limit on list of (real) cpu parameters
- * nparams(<=16) * ncpus(<=128) <= 2048.
+ * Upper limit on cpus involved in per-cpu stats
+ */
+const REMOTE_DOMAIN_GET_CPU_STATS_NCPUS_MAX = 128;
+
+/*
+ * Upper limit on list of per-cpu stats:
+ *  REMOTE_NODE_CPU_STATS_MAX * REMOTE_DOMAIN_GET_CPU_STATS_MAX
  */
 const REMOTE_DOMAIN_GET_CPU_STATS_MAX = 2048;



-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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