[PULL 58/71] backends: Simplify host_memory_backend_memory_complete()

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Return early if bc->alloc is NULL. De-indent the if() ladder.

Note, this avoids a pointless call to error_propagate() with
errp=NULL at the 'out:' label.

Change trivial when reviewed with 'git-diff --ignore-all-space'.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Message-Id: <20231120213301.24349-16-philmd@linaro.org>
---
 backends/hostmem.c | 133 +++++++++++++++++++++++----------------------
 1 file changed, 67 insertions(+), 66 deletions(-)

diff --git a/backends/hostmem.c b/backends/hostmem.c
index 747e7838c0..1723c19165 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -328,83 +328,84 @@ host_memory_backend_memory_complete(UserCreatable *uc, Error **errp)
     void *ptr;
     uint64_t sz;
 
-    if (bc->alloc) {
-        bc->alloc(backend, &local_err);
-        if (local_err) {
-            goto out;
-        }
+    if (!bc->alloc) {
+        return;
+    }
+    bc->alloc(backend, &local_err);
+    if (local_err) {
+        goto out;
+    }
 
-        ptr = memory_region_get_ram_ptr(&backend->mr);
-        sz = memory_region_size(&backend->mr);
+    ptr = memory_region_get_ram_ptr(&backend->mr);
+    sz = memory_region_size(&backend->mr);
 
-        if (backend->merge) {
-            qemu_madvise(ptr, sz, QEMU_MADV_MERGEABLE);
-        }
-        if (!backend->dump) {
-            qemu_madvise(ptr, sz, QEMU_MADV_DONTDUMP);
-        }
+    if (backend->merge) {
+        qemu_madvise(ptr, sz, QEMU_MADV_MERGEABLE);
+    }
+    if (!backend->dump) {
+        qemu_madvise(ptr, sz, QEMU_MADV_DONTDUMP);
+    }
 #ifdef CONFIG_NUMA
-        unsigned long lastbit = find_last_bit(backend->host_nodes, MAX_NODES);
-        /* lastbit == MAX_NODES means maxnode = 0 */
-        unsigned long maxnode = (lastbit + 1) % (MAX_NODES + 1);
-        /* ensure policy won't be ignored in case memory is preallocated
-         * before mbind(). note: MPOL_MF_STRICT is ignored on hugepages so
-         * this doesn't catch hugepage case. */
-        unsigned flags = MPOL_MF_STRICT | MPOL_MF_MOVE;
-        int mode = backend->policy;
+    unsigned long lastbit = find_last_bit(backend->host_nodes, MAX_NODES);
+    /* lastbit == MAX_NODES means maxnode = 0 */
+    unsigned long maxnode = (lastbit + 1) % (MAX_NODES + 1);
+    /* ensure policy won't be ignored in case memory is preallocated
+     * before mbind(). note: MPOL_MF_STRICT is ignored on hugepages so
+     * this doesn't catch hugepage case. */
+    unsigned flags = MPOL_MF_STRICT | MPOL_MF_MOVE;
+    int mode = backend->policy;
 
-        /* check for invalid host-nodes and policies and give more verbose
-         * error messages than mbind(). */
-        if (maxnode && backend->policy == MPOL_DEFAULT) {
-            error_setg(errp, "host-nodes must be empty for policy default,"
-                       " or you should explicitly specify a policy other"
-                       " than default");
-            return;
-        } else if (maxnode == 0 && backend->policy != MPOL_DEFAULT) {
-            error_setg(errp, "host-nodes must be set for policy %s",
-                       HostMemPolicy_str(backend->policy));
-            return;
-        }
+    /* check for invalid host-nodes and policies and give more verbose
+     * error messages than mbind(). */
+    if (maxnode && backend->policy == MPOL_DEFAULT) {
+        error_setg(errp, "host-nodes must be empty for policy default,"
+                   " or you should explicitly specify a policy other"
+                   " than default");
+        return;
+    } else if (maxnode == 0 && backend->policy != MPOL_DEFAULT) {
+        error_setg(errp, "host-nodes must be set for policy %s",
+                   HostMemPolicy_str(backend->policy));
+        return;
+    }
 
-        /* We can have up to MAX_NODES nodes, but we need to pass maxnode+1
-         * as argument to mbind() due to an old Linux bug (feature?) which
-         * cuts off the last specified node. This means backend->host_nodes
-         * must have MAX_NODES+1 bits available.
-         */
-        assert(sizeof(backend->host_nodes) >=
-               BITS_TO_LONGS(MAX_NODES + 1) * sizeof(unsigned long));
-        assert(maxnode <= MAX_NODES);
+    /* We can have up to MAX_NODES nodes, but we need to pass maxnode+1
+     * as argument to mbind() due to an old Linux bug (feature?) which
+     * cuts off the last specified node. This means backend->host_nodes
+     * must have MAX_NODES+1 bits available.
+     */
+    assert(sizeof(backend->host_nodes) >=
+           BITS_TO_LONGS(MAX_NODES + 1) * sizeof(unsigned long));
+    assert(maxnode <= MAX_NODES);
 
 #ifdef HAVE_NUMA_HAS_PREFERRED_MANY
-        if (mode == MPOL_PREFERRED && numa_has_preferred_many() > 0) {
-            /*
-             * Replace with MPOL_PREFERRED_MANY otherwise the mbind() below
-             * silently picks the first node.
-             */
-            mode = MPOL_PREFERRED_MANY;
-        }
+    if (mode == MPOL_PREFERRED && numa_has_preferred_many() > 0) {
+        /*
+         * Replace with MPOL_PREFERRED_MANY otherwise the mbind() below
+         * silently picks the first node.
+         */
+        mode = MPOL_PREFERRED_MANY;
+    }
 #endif
 
-        if (maxnode &&
-            mbind(ptr, sz, mode, backend->host_nodes, maxnode + 1, flags)) {
-            if (backend->policy != MPOL_DEFAULT || errno != ENOSYS) {
-                error_setg_errno(errp, errno,
-                                 "cannot bind memory to host NUMA nodes");
-                return;
-            }
+    if (maxnode &&
+        mbind(ptr, sz, mode, backend->host_nodes, maxnode + 1, flags)) {
+        if (backend->policy != MPOL_DEFAULT || errno != ENOSYS) {
+            error_setg_errno(errp, errno,
+                             "cannot bind memory to host NUMA nodes");
+            return;
         }
+    }
 #endif
-        /* Preallocate memory after the NUMA policy has been instantiated.
-         * This is necessary to guarantee memory is allocated with
-         * specified NUMA policy in place.
-         */
-        if (backend->prealloc) {
-            qemu_prealloc_mem(memory_region_get_fd(&backend->mr), ptr, sz,
-                              backend->prealloc_threads,
-                              backend->prealloc_context, &local_err);
-            if (local_err) {
-                goto out;
-            }
+    /* Preallocate memory after the NUMA policy has been instantiated.
+     * This is necessary to guarantee memory is allocated with
+     * specified NUMA policy in place.
+     */
+    if (backend->prealloc) {
+        qemu_prealloc_mem(memory_region_get_fd(&backend->mr), ptr, sz,
+                          backend->prealloc_threads,
+                          backend->prealloc_context, &local_err);
+        if (local_err) {
+            goto out;
         }
     }
 out:
-- 
2.41.0