Fix crash in lxcDomainSetMemoryParameters

The function doesn't check whether the request is made for active or
inactive domain.  Thus when the domain is not running it still tries
accessing non-existing cgroups (priv->cgroup, which is NULL).

I re-made the function in order for it to work the same way it's qemu
counterpart does.

Reproducer:
 1) Define an LXC domain
 2) Do 'virsh memtune <domain> --hard-limit 133T'

Backtrace:
 Thread 6 (Thread 0x7fffec8c0700 (LWP 26826)):
 #0  0x00007ffff70edcc4 in virCgroupPathOfController (group=0x0, controller=3,
     key=0x7ffff75734bd "memory.limit_in_bytes", path=0x7fffec8bf718) at util/vircgroup.c:1764
 #1  0x00007ffff70e9206 in virCgroupSetValueStr (group=0x0, controller=3,
     key=0x7ffff75734bd "memory.limit_in_bytes", value=0x7fffe409f360 "1073741824")
     at util/vircgroup.c:669
 #2  0x00007ffff70e98b4 in virCgroupSetValueU64 (group=0x0, controller=3,
     key=0x7ffff75734bd "memory.limit_in_bytes", value=1073741824) at util/vircgroup.c:740
 #3  0x00007ffff70ee518 in virCgroupSetMemory (group=0x0, kb=1048576) at util/vircgroup.c:1904
 #4  0x00007ffff70ee675 in virCgroupSetMemoryHardLimit (group=0x0, kb=1048576)
     at util/vircgroup.c:1944
 #5  0x00005555557d54c8 in lxcDomainSetMemoryParameters (dom=0x7fffe40cc420,
     params=0x7fffe409f100, nparams=1, flags=0) at lxc/lxc_driver.c:774
 #6  0x00007ffff72c20f9 in virDomainSetMemoryParameters (domain=0x7fffe40cc420,
     params=0x7fffe409f100, nparams=1, flags=0) at libvirt.c:4051
 #7  0x000055555561365f in remoteDispatchDomainSetMemoryParameters (server=0x555555eb7e00,
     client=0x555555ec4b10, msg=0x555555eb94e0, rerr=0x7fffec8bfb70, args=0x7fffe40b8510)
     at remote_dispatch.h:7621
 #8  0x00005555556133fd in remoteDispatchDomainSetMemoryParametersHelper (server=0x555555eb7e00,
     client=0x555555ec4b10, msg=0x555555eb94e0, rerr=0x7fffec8bfb70, args=0x7fffe40b8510,
     ret=0x7fffe40b84f0) at remote_dispatch.h:7591
 #9  0x00007ffff73b293f in virNetServerProgramDispatchCall (prog=0x555555ec3ae0,
     server=0x555555eb7e00, client=0x555555ec4b10, msg=0x555555eb94e0)
     at rpc/virnetserverprogram.c:435
 #10 0x00007ffff73b207f in virNetServerProgramDispatch (prog=0x555555ec3ae0,
     server=0x555555eb7e00, client=0x555555ec4b10, msg=0x555555eb94e0)
     at rpc/virnetserverprogram.c:305
 #11 0x00007ffff73a4d2c in virNetServerProcessMsg (srv=0x555555eb7e00, client=0x555555ec4b10,
     prog=0x555555ec3ae0, msg=0x555555eb94e0) at rpc/virnetserver.c:165
 #12 0x00007ffff73a4e8d in virNetServerHandleJob (jobOpaque=0x555555ec3e30, opaque=0x555555eb7e00)
     at rpc/virnetserver.c:186
 #13 0x00007ffff7187f3f in virThreadPoolWorker (opaque=0x555555eb7ac0) at util/virthreadpool.c:144
 #14 0x00007ffff718733a in virThreadHelper (data=0x555555eb7890) at util/virthreadpthread.c:161
 #15 0x00007ffff468ed89 in start_thread (arg=0x7fffec8c0700) at pthread_create.c:308
 #16 0x00007ffff3da26bd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

src/lxc/lxc_driver.c

@@ -742,12 +742,24 @@ lxcDomainSetMemoryParameters(virDomainPtr dom,
                              int nparams,
                              unsigned int flags)
 {
-    size_t i;
+    virCapsPtr caps = NULL;
+    virDomainDefPtr vmdef = NULL;
     virDomainObjPtr vm = NULL;
+    virLXCDomainObjPrivatePtr priv = NULL;
+    virLXCDriverConfigPtr cfg = NULL;
+    virLXCDriverPtr driver = dom->conn->privateData;
+    unsigned long long hard_limit;
+    unsigned long long soft_limit;
+    unsigned long long swap_hard_limit;
+    bool set_hard_limit = false;
+    bool set_soft_limit = false;
+    bool set_swap_hard_limit = false;
+    int rc;
     int ret = -1;
-    virLXCDomainObjPrivatePtr priv;
 
-    virCheckFlags(0, -1);
+    virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
+                  VIR_DOMAIN_AFFECT_CONFIG, -1);
+
     if (virTypedParamsValidate(params, nparams,
                                VIR_DOMAIN_MEMORY_HARD_LIMIT,
                                VIR_TYPED_PARAM_ULLONG,
@@ -762,29 +774,97 @@ lxcDomainSetMemoryParameters(virDomainPtr dom,
         goto cleanup;
 
     priv = vm->privateData;
+    cfg = virLXCDriverGetConfig(driver);
 
-    if (virDomainSetMemoryParametersEnsureACL(dom->conn, vm->def, flags) < 0)
+    if (virDomainSetMemoryParametersEnsureACL(dom->conn, vm->def, flags) < 0 ||
+        !(caps = virLXCDriverGetCapabilities(driver, false)) ||
+        virDomainLiveConfigHelperMethod(caps, driver->xmlopt,
+                                        vm, &flags, &vmdef) < 0)
         goto cleanup;
 
-    ret = 0;
-    for (i = 0; i < nparams; i++) {
-        virTypedParameterPtr param = &params[i];
+    if (flags & VIR_DOMAIN_AFFECT_LIVE &&
+        !virCgroupHasController(priv->cgroup, VIR_CGROUP_CONTROLLER_MEMORY)) {
+        virReportError(VIR_ERR_OPERATION_INVALID,
+                       "%s", _("cgroup memory controller is not mounted"));
+        goto cleanup;
+    }
+
+#define VIR_GET_LIMIT_PARAMETER(PARAM, VALUE)                                \
+    if ((rc = virTypedParamsGetULLong(params, nparams, PARAM, &VALUE)) < 0)  \
+        goto cleanup;                                                        \
+                                                                             \
+    if (rc == 1)                                                             \
+        set_ ## VALUE = true;
+
+    VIR_GET_LIMIT_PARAMETER(VIR_DOMAIN_MEMORY_SWAP_HARD_LIMIT, swap_hard_limit)
+    VIR_GET_LIMIT_PARAMETER(VIR_DOMAIN_MEMORY_HARD_LIMIT, hard_limit)
+    VIR_GET_LIMIT_PARAMETER(VIR_DOMAIN_MEMORY_SOFT_LIMIT, soft_limit)
+
+#undef VIR_GET_LIMIT_PARAMETER
+
+    /* Swap hard limit must be greater than hard limit.
+     * Note that limit of 0 denotes unlimited */
+    if (set_swap_hard_limit || set_hard_limit) {
+        unsigned long long mem_limit = vm->def->mem.hard_limit;
+        unsigned long long swap_limit = vm->def->mem.swap_hard_limit;
+
+        if (set_swap_hard_limit)
+            swap_limit = swap_hard_limit;
 
-        if (STREQ(param->field, VIR_DOMAIN_MEMORY_HARD_LIMIT)) {
-            if (virCgroupSetMemoryHardLimit(priv->cgroup, params[i].value.ul) < 0)
-                ret = -1;
-        } else if (STREQ(param->field, VIR_DOMAIN_MEMORY_SOFT_LIMIT)) {
-            if (virCgroupSetMemorySoftLimit(priv->cgroup, params[i].value.ul) < 0)
-                ret = -1;
-        } else if (STREQ(param->field, VIR_DOMAIN_MEMORY_SWAP_HARD_LIMIT)) {
-            if (virCgroupSetMemSwapHardLimit(priv->cgroup, params[i].value.ul) < 0)
-                ret = -1;
+        if (set_hard_limit)
+            mem_limit = hard_limit;
+
+        if (virCompareLimitUlong(mem_limit, swap_limit) > 0) {
+            virReportError(VIR_ERR_INVALID_ARG, "%s",
+                           _("memory hard_limit tunable value must be lower "
+                             "than or equal to swap_hard_limit"));
+            goto cleanup;
         }
     }
 
+#define LXC_SET_MEM_PARAMETER(FUNC, VALUE)                                     \
+    if (set_ ## VALUE) {                                                        \
+        if (flags & VIR_DOMAIN_AFFECT_LIVE) {                                   \
+            if ((rc = FUNC(priv->cgroup, VALUE)) < 0) {                         \
+                virReportSystemError(-rc, _("unable to set memory %s tunable"), \
+                                     #VALUE);                                   \
+                                                                                \
+                goto cleanup;                                                   \
+            }                                                                   \
+            vm->def->mem.VALUE = VALUE;                                         \
+        }                                                                       \
+                                                                                \
+        if (flags & VIR_DOMAIN_AFFECT_CONFIG)                                   \
+            vmdef->mem.VALUE = VALUE;                                   \
+    }
+
+    /* Soft limit doesn't clash with the others */
+    LXC_SET_MEM_PARAMETER(virCgroupSetMemorySoftLimit, soft_limit);
+
+    /* set hard limit before swap hard limit if decreasing it */
+    if (virCompareLimitUlong(vm->def->mem.hard_limit, hard_limit) > 0) {
+        LXC_SET_MEM_PARAMETER(virCgroupSetMemoryHardLimit, hard_limit);
+        /* inhibit changing the limit a second time */
+        set_hard_limit = false;
+    }
+
+    LXC_SET_MEM_PARAMETER(virCgroupSetMemSwapHardLimit, swap_hard_limit);
+
+    /* otherwise increase it after swap hard limit */
+    LXC_SET_MEM_PARAMETER(virCgroupSetMemoryHardLimit, hard_limit);
+
+#undef LXC_SET_MEM_PARAMETER
+
+    if (flags & VIR_DOMAIN_AFFECT_CONFIG &&
+        virDomainSaveConfig(cfg->configDir, vmdef) < 0)
+        goto cleanup;
+
+    ret = 0;
 cleanup:
     if (vm)
         virObjectUnlock(vm);
+    virObjectUnref(caps);
+    virObjectUnref(cfg);
     return ret;
 }