[PATCH 14/24] libxl: allow to set the ratelimit value online for Credit2

[Dario Faggioli <dario.faggioli@citrix.com>]

This is the remaining part of the plumbing (the libxl
one) necessary to be able to change the value of the
ratelimit_us parameter online, for Credit2 (like it is
already for Credit1).

Note that, so far, we were rejecting (for Credit1) a
new value of zero, despite it is a pretty nice way to
ask for the rate limiting to be disabled, and the
hypervisor is already capable of dealing with it in
that way.

Therefore, we change things so that it is possible to
do so, both for Credit1 and Credit2

While there, fix the error handling path (make it
compliant with libxl's codying style) in Credit1
rate limiting related functions.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
---
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>
---
 tools/libxl/libxl.c         |  111 ++++++++++++++++++++++++++++++++++---------
 tools/libxl/libxl.h         |    4 ++
 tools/libxl/libxl_types.idl |    4 ++
 3 files changed, 95 insertions(+), 24 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 6a50e49..d6a8d02 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -5229,69 +5229,132 @@ static int sched_credit_domain_set(libxl__gc *gc, uint32_t domid,
     return 0;
 }
 
+static int sched_ratelimit_check(libxl__gc *gc, int ratelimit)
+{
+    if (ratelimit != 0 &&
+        (ratelimit <  XEN_SYSCTL_SCHED_RATELIMIT_MIN ||
+         ratelimit > XEN_SYSCTL_SCHED_RATELIMIT_MAX)) {
+        LOG(ERROR, "Ratelimit out of range, valid range is from %d to %d",
+            XEN_SYSCTL_SCHED_RATELIMIT_MIN, XEN_SYSCTL_SCHED_RATELIMIT_MAX);
+        return ERROR_INVAL;
+    }
+
+    return 0;
+}
+
 int libxl_sched_credit_params_get(libxl_ctx *ctx, uint32_t poolid,
                                   libxl_sched_credit_params *scinfo)
 {
     struct xen_sysctl_credit_schedule sparam;
-    int rc;
+    int r, rc;
     GC_INIT(ctx);
 
-    rc = xc_sched_credit_params_get(ctx->xch, poolid, &sparam);
-    if (rc != 0) {
-        LOGE(ERROR, "getting sched credit param");
-        GC_FREE;
-        return ERROR_FAIL;
+    r = xc_sched_credit_params_get(ctx->xch, poolid, &sparam);
+    if (r < 0) {
+        LOGE(ERROR, "getting Credit scheduler parameters");
+        rc = ERROR_FAIL;
+        goto out;
     }
 
     scinfo->tslice_ms = sparam.tslice_ms;
     scinfo->ratelimit_us = sparam.ratelimit_us;
 
+    rc = 0;
+ out:
     GC_FREE;
-    return 0;
+    return rc;
 }
 
 int libxl_sched_credit_params_set(libxl_ctx *ctx, uint32_t poolid,
                                   libxl_sched_credit_params *scinfo)
 {
     struct xen_sysctl_credit_schedule sparam;
-    int rc=0;
+    int r, rc;
     GC_INIT(ctx);
 
     if (scinfo->tslice_ms <  XEN_SYSCTL_CSCHED_TSLICE_MIN
         || scinfo->tslice_ms > XEN_SYSCTL_CSCHED_TSLICE_MAX) {
         LOG(ERROR, "Time slice out of range, valid range is from %d to %d",
             XEN_SYSCTL_CSCHED_TSLICE_MIN, XEN_SYSCTL_CSCHED_TSLICE_MAX);
-        GC_FREE;
-        return ERROR_INVAL;
+        rc = ERROR_INVAL;
+        goto out;
     }
-    if (scinfo->ratelimit_us <  XEN_SYSCTL_SCHED_RATELIMIT_MIN
-        || scinfo->ratelimit_us > XEN_SYSCTL_SCHED_RATELIMIT_MAX) {
-        LOG(ERROR, "Ratelimit out of range, valid range is from %d to %d",
-            XEN_SYSCTL_SCHED_RATELIMIT_MIN, XEN_SYSCTL_SCHED_RATELIMIT_MAX);
-        GC_FREE;
-        return ERROR_INVAL;
+    rc = sched_ratelimit_check(gc, scinfo->ratelimit_us);
+    if (rc) {
+        goto out;
     }
     if (scinfo->ratelimit_us > scinfo->tslice_ms*1000) {
         LOG(ERROR, "Ratelimit cannot be greater than timeslice");
-        GC_FREE;
-        return ERROR_INVAL;
+        rc = ERROR_INVAL;
+        goto out;
     }
 
     sparam.tslice_ms = scinfo->tslice_ms;
     sparam.ratelimit_us = scinfo->ratelimit_us;
 
-    rc = xc_sched_credit_params_set(ctx->xch, poolid, &sparam);
-    if ( rc < 0 ) {
-        LOGE(ERROR, "setting sched credit param");
-        GC_FREE;
-        return ERROR_FAIL;
+    r = xc_sched_credit_params_set(ctx->xch, poolid, &sparam);
+    if ( r < 0 ) {
+        LOGE(ERROR, "Setting Credit scheduler parameters");
+        rc = ERROR_FAIL;
+        goto out;
     }
 
     scinfo->tslice_ms = sparam.tslice_ms;
     scinfo->ratelimit_us = sparam.ratelimit_us;
 
+ out:
     GC_FREE;
-    return 0;
+    return rc;
+}
+
+int libxl_sched_credit2_params_get(libxl_ctx *ctx, uint32_t poolid,
+                                   libxl_sched_credit2_params *scinfo)
+{
+    struct xen_sysctl_credit2_schedule sparam;
+    int r, rc;
+    GC_INIT(ctx);
+
+    r = xc_sched_credit2_params_get(ctx->xch, poolid, &sparam);
+    if (r < 0) {
+        LOGE(ERROR, "getting Credit2 scheduler parameters");
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    scinfo->ratelimit_us = sparam.ratelimit_us;
+
+    rc = 0;
+ out:
+    GC_FREE;
+    return rc;
+}
+
+int libxl_sched_credit2_params_set(libxl_ctx *ctx, uint32_t poolid,
+                                   libxl_sched_credit2_params *scinfo)
+{
+    struct xen_sysctl_credit2_schedule sparam;
+    int r, rc;
+    GC_INIT(ctx);
+
+    rc = sched_ratelimit_check(gc, scinfo->ratelimit_us);
+    if (rc) {
+        goto out;
+    }
+
+    sparam.ratelimit_us = scinfo->ratelimit_us;
+
+    r = xc_sched_credit2_params_set(ctx->xch, poolid, &sparam);
+    if ( r < 0 ) {
+        LOGE(ERROR, "Setting Credit2 scheduler parameters");
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    scinfo->ratelimit_us = sparam.ratelimit_us;
+
+ out:
+    GC_FREE;
+    return rc;
 }
 
 static int sched_credit2_domain_get(libxl__gc *gc, uint32_t domid,
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index ae21302..efc5912 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -1978,6 +1978,10 @@ int libxl_sched_credit_params_get(libxl_ctx *ctx, uint32_t poolid,
                                   libxl_sched_credit_params *scinfo);
 int libxl_sched_credit_params_set(libxl_ctx *ctx, uint32_t poolid,
                                   libxl_sched_credit_params *scinfo);
+int libxl_sched_credit2_params_get(libxl_ctx *ctx, uint32_t poolid,
+                                   libxl_sched_credit2_params *scinfo);
+int libxl_sched_credit2_params_set(libxl_ctx *ctx, uint32_t poolid,
+                                   libxl_sched_credit2_params *scinfo);
 
 /* Scheduler Per-domain parameters */
 
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index ef614be..38a4222 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -833,6 +833,10 @@ libxl_sched_credit_params = Struct("sched_credit_params", [
     ("ratelimit_us", integer),
     ], dispose_fn=None)
 
+libxl_sched2_credit_params = Struct("sched_credit2_params", [
+    ("ratelimit_us", integer),
+    ], dispose_fn=None)
+
 libxl_domain_remus_info = Struct("domain_remus_info",[
     ("interval",     integer),
     ("allow_unsafe", libxl_defbool),


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