[PATCH v4 05/15] xl: implement and enable dryrun mode for `xl vcpu-pin'

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

As it can be useful to see if the outcome of some complex vCPU
pinning bitmap specification looks as expected.

This also allow for the introduction of some automatic testing
and verification for the bitmap parsing code, as it happens
already in check-xl-disk-parse and check-xl-vif-parse.

In particular, to make the above possible, this commit also
changes the implementation of the vcpu-pin command so that,
instead of always returning 0, it returns an error if the
parsing fails.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
---
Changes since v2 (of original series):
 * fixed a typo in the changelog
---
 tools/libxl/xl_cmdimpl.c  |   48 +++++++++++++++++++++++++++++++++------------
 tools/libxl/xl_cmdtable.c |    2 +-
 2 files changed, 36 insertions(+), 14 deletions(-)

diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 8138cfe..7b4d058 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -4583,40 +4583,62 @@ int main_vcpulist(int argc, char **argv)
     return 0;
 }
 
-static void vcpupin(uint32_t domid, const char *vcpu, char *cpu)
+static int vcpupin(uint32_t domid, const char *vcpu, char *cpu)
 {
     libxl_vcpuinfo *vcpuinfo;
     libxl_bitmap cpumap;
 
     uint32_t vcpuid;
     char *endptr;
-    int i, nb_vcpu;
+    int i, nb_cpu, nb_vcpu, rc = -1;
+
+    libxl_bitmap_init(&cpumap);
 
     vcpuid = strtoul(vcpu, &endptr, 10);
     if (vcpu == endptr) {
         if (strcmp(vcpu, "all")) {
             fprintf(stderr, "Error: Invalid argument.\n");
-            return;
+            goto out;
         }
         vcpuid = -1;
     }
 
-    if (libxl_cpu_bitmap_alloc(ctx, &cpumap, 0)) {
-        goto vcpupin_out;
-    }
+    if (libxl_cpu_bitmap_alloc(ctx, &cpumap, 0))
+        goto out;
 
     if (vcpupin_parse(cpu, &cpumap))
-        goto vcpupin_out1;
+        goto out;
+
+    if (dryrun_only) {
+        nb_cpu = libxl_get_nr_cpus(ctx);
+        if (nb_cpu <= 0) {
+            fprintf(stderr, "libxl_get_nr_cpus failed.\n");
+            goto out;
+        }
+
+        fprintf(stdout, "cpumap: ");
+        print_bitmap(cpumap.map, nb_cpu, stdout);
+        fprintf(stdout, "\n");
+
+        if (ferror(stdout) || fflush(stdout)) {
+            perror("stdout");
+            exit(-1);
+        }
+
+        rc = 0;
+        goto out;
+    }
 
     if (vcpuid != -1) {
         if (libxl_set_vcpuaffinity(ctx, domid, vcpuid, &cpumap) == -1) {
             fprintf(stderr, "Could not set affinity for vcpu `%u'.\n", vcpuid);
+            goto out;
         }
     }
     else {
         if (!(vcpuinfo = libxl_list_vcpu(ctx, domid, &nb_vcpu, &i))) {
             fprintf(stderr, "libxl_list_vcpu failed.\n");
-            goto vcpupin_out1;
+            goto out;
         }
         for (i = 0; i < nb_vcpu; i++) {
             if (libxl_set_vcpuaffinity(ctx, domid, vcpuinfo[i].vcpuid,
@@ -4627,10 +4649,11 @@ static void vcpupin(uint32_t domid, const char *vcpu, char *cpu)
         }
         libxl_vcpuinfo_list_free(vcpuinfo, nb_vcpu);
     }
-  vcpupin_out1:
+
+    rc = 0;
+ out:
     libxl_bitmap_dispose(&cpumap);
-  vcpupin_out:
-    ;
+    return rc;
 }
 
 int main_vcpupin(int argc, char **argv)
@@ -4641,8 +4664,7 @@ int main_vcpupin(int argc, char **argv)
         /* No options */
     }
 
-    vcpupin(find_domain(argv[optind]), argv[optind+1] , argv[optind+2]);
-    return 0;
+    return vcpupin(find_domain(argv[optind]), argv[optind+1] , argv[optind+2]);
 }
 
 static void vcpuset(uint32_t domid, const char* nr_vcpus, int check_host)
diff --git a/tools/libxl/xl_cmdtable.c b/tools/libxl/xl_cmdtable.c
index 7709206..ebe0220 100644
--- a/tools/libxl/xl_cmdtable.c
+++ b/tools/libxl/xl_cmdtable.c
@@ -211,7 +211,7 @@ struct cmd_spec cmd_table[] = {
       "[Domain, ...]",
     },
     { "vcpu-pin",
-      &main_vcpupin, 0, 1,
+      &main_vcpupin, 1, 1,
       "Set which CPUs a VCPU can use",
       "<Domain> <VCPU|all> <CPUs|all>",
     },