From: Michal Privoznik <mprivozn@redhat.com>
Date: Thu, 29 Jul 2021 13:39:08 +0000 (+0200)
Subject: vmx: Rework disk def allocation
X-Git-Tag: v7.7.0-rc1~185
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d628c5ded1d880845e4398f1b6cb3568550dba2c;p=thirdparty%2Flibvirt.git

vmx: Rework disk def allocation

The way we parse VMX configuration is rather unfortunate,
especially when it comes to disks. We allocate an array that can
handle all possible disks but leave the array counter (ndisks) at
zero and increase it only after successful parsing. But, we never
size the array down to release unneeded chunks of memory.

We can do better: we can use VIR_APPEND_ELEMENT() to allocate
array as needed.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---

diff --git a/src/vmx/vmx.c b/src/vmx/vmx.c
index 8a3acbfb8f..4dc29b57a6 100644
--- a/src/vmx/vmx.c
+++ b/src/vmx/vmx.c
@@ -1719,10 +1719,6 @@ virVMXParseConfig(virVMXContext *ctx,
     if (def->graphics[def->ngraphics] != NULL)
         ++def->ngraphics;
 
-    /* def:disks: 4 * 15 scsi + 4 * 30 sata + 2 * 2 ide + 2 floppy = 186 */
-    def->disks = g_new0(virDomainDiskDef *, 186);
-    def->ndisks = 0;
-
     /* def:disks (scsi) */
     for (controller = 0; controller < 4; ++controller) {
         if (virVMXParseSCSIController(conf, controller, &present,
@@ -1734,6 +1730,8 @@ virVMXParseConfig(virVMXContext *ctx,
             continue;
 
         for (unit = 0; unit < 16; ++unit) {
+            g_autoptr(virDomainDiskDef) disk = NULL;
+
             if (unit == 7) {
                 /*
                  * SCSI unit 7 is assigned to the SCSI controller and cannot be
@@ -1744,25 +1742,22 @@ virVMXParseConfig(virVMXContext *ctx,
 
             if (virVMXParseDisk(ctx, xmlopt, conf, VIR_DOMAIN_DISK_DEVICE_DISK,
                                 VIR_DOMAIN_DISK_BUS_SCSI, controller, unit,
-                                &def->disks[def->ndisks], def) < 0) {
+                                &disk, def) < 0) {
                 goto cleanup;
             }
 
-            if (def->disks[def->ndisks] != NULL) {
-                ++def->ndisks;
-                continue;
-            }
-
-            if (virVMXParseDisk(ctx, xmlopt, conf, VIR_DOMAIN_DISK_DEVICE_CDROM,
-                                 VIR_DOMAIN_DISK_BUS_SCSI, controller, unit,
-                                 &def->disks[def->ndisks], def) < 0) {
+            if (!disk &&
+                virVMXParseDisk(ctx, xmlopt, conf, VIR_DOMAIN_DISK_DEVICE_CDROM,
+                                VIR_DOMAIN_DISK_BUS_SCSI, controller, unit,
+                                &disk, def) < 0) {
                 goto cleanup;
             }
 
-            if (def->disks[def->ndisks] != NULL)
-                ++def->ndisks;
-        }
+            if (!disk)
+                continue;
 
+            VIR_APPEND_ELEMENT(def->disks, def->ndisks, disk);
+        }
     }
 
     /* add all the SCSI controllers we've seen, up until the last one that is
@@ -1787,27 +1782,26 @@ virVMXParseConfig(virVMXContext *ctx,
             continue;
 
         for (unit = 0; unit < 30; ++unit) {
+            g_autoptr(virDomainDiskDef) disk = NULL;
+
             if (virVMXParseDisk(ctx, xmlopt, conf, VIR_DOMAIN_DISK_DEVICE_DISK,
                                 VIR_DOMAIN_DISK_BUS_SATA, controller, unit,
-                                &def->disks[def->ndisks], def) < 0) {
+                                &disk, def) < 0) {
                 goto cleanup;
             }
 
-            if (def->disks[def->ndisks] != NULL) {
-                ++def->ndisks;
-                continue;
-            }
-
-            if (virVMXParseDisk(ctx, xmlopt, conf, VIR_DOMAIN_DISK_DEVICE_CDROM,
+            if (!disk &&
+                virVMXParseDisk(ctx, xmlopt, conf, VIR_DOMAIN_DISK_DEVICE_CDROM,
                                  VIR_DOMAIN_DISK_BUS_SATA, controller, unit,
-                                 &def->disks[def->ndisks], def) < 0) {
+                                 &disk, def) < 0) {
                 goto cleanup;
             }
 
-            if (def->disks[def->ndisks] != NULL)
-                ++def->ndisks;
-        }
+            if (!disk)
+                continue;
 
+            VIR_APPEND_ELEMENT(def->disks, def->ndisks, disk);
+        }
     }
 
     /* add all the SATA controllers we've seen, up until the last one that is
@@ -1824,38 +1818,42 @@ virVMXParseConfig(virVMXContext *ctx,
     /* def:disks (ide) */
     for (bus = 0; bus < 2; ++bus) {
         for (unit = 0; unit < 2; ++unit) {
+            g_autoptr(virDomainDiskDef) disk = NULL;
+
             if (virVMXParseDisk(ctx, xmlopt, conf, VIR_DOMAIN_DISK_DEVICE_DISK,
                                 VIR_DOMAIN_DISK_BUS_IDE, bus, unit,
-                                &def->disks[def->ndisks], def) < 0) {
+                                &disk, def) < 0) {
                 goto cleanup;
             }
 
-            if (def->disks[def->ndisks] != NULL) {
-                ++def->ndisks;
-                continue;
-            }
-
-            if (virVMXParseDisk(ctx, xmlopt, conf, VIR_DOMAIN_DISK_DEVICE_CDROM,
+            if (!disk &&
+                virVMXParseDisk(ctx, xmlopt, conf, VIR_DOMAIN_DISK_DEVICE_CDROM,
                                 VIR_DOMAIN_DISK_BUS_IDE, bus, unit,
-                                &def->disks[def->ndisks], def) < 0) {
+                                &disk, def) < 0) {
                 goto cleanup;
             }
 
-            if (def->disks[def->ndisks] != NULL)
-                ++def->ndisks;
+            if (!disk)
+                continue;
+
+            VIR_APPEND_ELEMENT(def->disks, def->ndisks, disk);
         }
     }
 
     /* def:disks (floppy) */
     for (unit = 0; unit < 2; ++unit) {
+        g_autoptr(virDomainDiskDef) disk = NULL;
+
         if (virVMXParseDisk(ctx, xmlopt, conf, VIR_DOMAIN_DISK_DEVICE_FLOPPY,
                             VIR_DOMAIN_DISK_BUS_FDC, 0, unit,
-                            &def->disks[def->ndisks], def) < 0) {
+                            &disk, def) < 0) {
             goto cleanup;
         }
 
-        if (def->disks[def->ndisks] != NULL)
-            ++def->ndisks;
+        if (!disk)
+            continue;
+
+        VIR_APPEND_ELEMENT(def->disks, def->ndisks, disk);
     }
 
     /* def:fss */