error: Avoid error_propagate() after migrate_add_blocker()

When migrate_add_blocker(blocker, &errp) is followed by
error_propagate(errp, err), we can often just as well do
migrate_add_blocker(..., errp).

Do that with this Coccinelle script:

    @@
    expression blocker, err, errp;
    expression ret;
    @@
    -    ret = migrate_add_blocker(blocker, &err);
    -    if (err) {
    +    ret = migrate_add_blocker(blocker, errp);
    +    if (ret < 0) {
             ... when != err;
    -        error_propagate(errp, err);
             ...
         }

    @@
    expression blocker, err, errp;
    @@
    -    migrate_add_blocker(blocker, &err);
    -    if (err) {
    +    if (migrate_add_blocker(blocker, errp) < 0) {
             ... when != err;
    -        error_propagate(errp, err);
             ...
         }

Double-check @err is not used afterwards.  Dereferencing it would be
use after free, but checking whether it's null would be legitimate.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200707160613.848843-43-armbru@redhat.com>

diff --git a/block/parallels.c b/block/parallels.c
index f489c0d4ba31b20566cded202c089702eddbeffe..3c22dfdc9daa432a3c2ccf4b6910011207f54bae 100644 (file)
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -859,9 +859,8 @@ static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
     error_setg(&s->migration_blocker, "The Parallels format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
-    ret = migrate_add_blocker(s->migration_blocker, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    ret = migrate_add_blocker(s->migration_blocker, errp);
+    if (ret < 0) {
         error_free(s->migration_blocker);
         goto fail;
     }

diff --git a/block/qcow.c b/block/qcow.c
index c22d1bf6b8bbef9a9386bc7e0db6e8421df350d2..1e134f34450b46e45b25d77f3b69947f7ea4a53a 100644 (file)
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -121,7 +121,6 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
     unsigned int len, i, shift;
     int ret;
     QCowHeader header;
-    Error *local_err = NULL;
     QCryptoBlockOpenOptions *crypto_opts = NULL;
     unsigned int cflags = 0;
     QDict *encryptopts = NULL;
@@ -314,9 +313,8 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
     error_setg(&s->migration_blocker, "The qcow format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
-    ret = migrate_add_blocker(s->migration_blocker, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    ret = migrate_add_blocker(s->migration_blocker, errp);
+    if (ret < 0) {
         error_free(s->migration_blocker);
         goto fail;
     }

diff --git a/block/vdi.c b/block/vdi.c
index 2496d51a4d2cb11e923b50ede9ef71bc8ed37159..5627e7d764aeeccba87e569f8209caf82dccaa35 100644 (file)
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -374,7 +374,6 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
     VdiHeader header;
     size_t bmap_size;
     int ret;
-    Error *local_err = NULL;
     QemuUUID uuid_link, uuid_parent;
 
     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
@@ -495,9 +494,8 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
     error_setg(&s->migration_blocker, "The vdi format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
-    ret = migrate_add_blocker(s->migration_blocker, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    ret = migrate_add_blocker(s->migration_blocker, errp);
+    if (ret < 0) {
         error_free(s->migration_blocker);
         goto fail_free_bmap;
     }

diff --git a/block/vhdx.c b/block/vhdx.c
index a36d9d924a3ef94b1daa748c918311c2dffccb35..791eb90263c758026ad1e15487e8d76ec15737a4 100644 (file)
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1089,9 +1089,8 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags,
     error_setg(&s->migration_blocker, "The vhdx format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
-    ret = migrate_add_blocker(s->migration_blocker, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    ret = migrate_add_blocker(s->migration_blocker, errp);
+    if (ret < 0) {
         error_free(s->migration_blocker);
         goto fail;
     }

diff --git a/block/vmdk.c b/block/vmdk.c
index 9a09193f3b1235e5ae0044b06e7a7d75944afd4c..28cec50f38c8b1b7bf1fb11690318143bfe08465 100644 (file)
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1263,7 +1263,6 @@ static int vmdk_open(BlockDriverState *bs, QDict *options, int flags,
     int ret;
     BDRVVmdkState *s = bs->opaque;
     uint32_t magic;
-    Error *local_err = NULL;
 
     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
                                BDRV_CHILD_IMAGE, false, errp);
@@ -1317,9 +1316,8 @@ static int vmdk_open(BlockDriverState *bs, QDict *options, int flags,
     error_setg(&s->migration_blocker, "The vmdk format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
-    ret = migrate_add_blocker(s->migration_blocker, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    ret = migrate_add_blocker(s->migration_blocker, errp);
+    if (ret < 0) {
         error_free(s->migration_blocker);
         goto fail;
     }

diff --git a/block/vpc.c b/block/vpc.c
index 131b9db6cc5171379e1084a95574cfeef5315f8b..890554277e6f503f67dec8c58a8a85374f83258c 100644 (file)
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -446,9 +446,8 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
     error_setg(&s->migration_blocker, "The vpc format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
-    ret = migrate_add_blocker(s->migration_blocker, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    ret = migrate_add_blocker(s->migration_blocker, errp);
+    if (ret < 0) {
         error_free(s->migration_blocker);
         goto fail;
     }

diff --git a/block/vvfat.c b/block/vvfat.c
index 24d36220d3ac8622ac7e894a518f0cf0e9b361d9..36b53c8757f95eaa128561ea4b9e9a4427635207 100644 (file)
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1141,7 +1141,6 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
     bool floppy;
     const char *dirname, *label;
     QemuOpts *opts;
-    Error *local_err = NULL;
     int ret;
 
 #ifdef DEBUG
@@ -1267,9 +1266,8 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
                    "The vvfat (rw) format used by node '%s' "
                    "does not support live migration",
                    bdrv_get_device_or_node_name(bs));
-        ret = migrate_add_blocker(s->migration_blocker, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        ret = migrate_add_blocker(s->migration_blocker, errp);
+        if (ret < 0) {
             error_free(s->migration_blocker);
             goto fail;
         }

diff --git a/hw/display/virtio-gpu-base.c b/hw/display/virtio-gpu-base.c
index c159351be3f8785f104512e2691e9a75a9a36701..7961308606571b93eff007c78e087448d8858b1b 100644 (file)
--- a/hw/display/virtio-gpu-base.c
+++ b/hw/display/virtio-gpu-base.c
@@ -128,7 +128,6 @@ virtio_gpu_base_device_realize(DeviceState *qdev,
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(qdev);
     VirtIOGPUBase *g = VIRTIO_GPU_BASE(qdev);
-    Error *local_err = NULL;
     int i;
 
     if (g->conf.max_outputs > VIRTIO_GPU_MAX_SCANOUTS) {
@@ -139,9 +138,7 @@ virtio_gpu_base_device_realize(DeviceState *qdev,
     g->use_virgl_renderer = false;
     if (virtio_gpu_virgl_enabled(g->conf)) {
         error_setg(&g->migration_blocker, "virgl is not yet migratable");
-        migrate_add_blocker(g->migration_blocker, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        if (migrate_add_blocker(g->migration_blocker, errp) < 0) {
             error_free(g->migration_blocker);
             return false;
         }

diff --git a/hw/intc/arm_gic_kvm.c b/hw/intc/arm_gic_kvm.c
index d7df423a7a3793798e4a35e4d35adf14ba182e73..07b95143c9eac15844cc2620fefc6328b7289153 100644 (file)
--- a/hw/intc/arm_gic_kvm.c
+++ b/hw/intc/arm_gic_kvm.c
@@ -517,9 +517,7 @@ static void kvm_arm_gic_realize(DeviceState *dev, Error **errp)
     if (!kvm_arm_gic_can_save_restore(s)) {
         error_setg(&s->migration_blocker, "This operating system kernel does "
                                           "not support vGICv2 migration");
-        migrate_add_blocker(s->migration_blocker, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        if (migrate_add_blocker(s->migration_blocker, errp) < 0) {
             error_free(s->migration_blocker);
             return;
         }

diff --git a/hw/intc/arm_gicv3_its_kvm.c b/hw/intc/arm_gicv3_its_kvm.c
index ad0ebabc87956558f07f4025f50573644b3d0a59..46835ed085a68956fc8c01407d1c14a756af8902 100644 (file)
--- a/hw/intc/arm_gicv3_its_kvm.c
+++ b/hw/intc/arm_gicv3_its_kvm.c
@@ -91,7 +91,6 @@ static void vm_change_state_handler(void *opaque, int running,
 static void kvm_arm_its_realize(DeviceState *dev, Error **errp)
 {
     GICv3ITSState *s = ARM_GICV3_ITS_COMMON(dev);
-    Error *local_err = NULL;
 
     s->dev_fd = kvm_create_device(kvm_state, KVM_DEV_TYPE_ARM_VGIC_ITS, false);
     if (s->dev_fd < 0) {
@@ -113,9 +112,7 @@ static void kvm_arm_its_realize(DeviceState *dev, Error **errp)
         GITS_CTLR)) {
         error_setg(&s->migration_blocker, "This operating system kernel "
                    "does not support vITS migration");
-        migrate_add_blocker(s->migration_blocker, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        if (migrate_add_blocker(s->migration_blocker, errp) < 0) {
             error_free(s->migration_blocker);
             return;
         }

diff --git a/hw/intc/arm_gicv3_kvm.c b/hw/intc/arm_gicv3_kvm.c
index ca43bf87caba0383b8d1cfe3ed1a4dbe6a781861..eddd07c7433aa85e5f49c2f50a59431eee8c6f36 100644 (file)
--- a/hw/intc/arm_gicv3_kvm.c
+++ b/hw/intc/arm_gicv3_kvm.c
@@ -858,9 +858,7 @@ static void kvm_arm_gicv3_realize(DeviceState *dev, Error **errp)
                                GICD_CTLR)) {
         error_setg(&s->migration_blocker, "This operating system kernel does "
                                           "not support vGICv3 migration");
-        migrate_add_blocker(s->migration_blocker, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        if (migrate_add_blocker(s->migration_blocker, errp) < 0) {
             error_free(s->migration_blocker);
             return;
         }

diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index a8dc9b377d000988c2f9a81ca137b3433a7d2076..fc128b25e2895e18b9bc2cbb129562d5146b5412 100644 (file)
--- a/hw/misc/ivshmem.c
+++ b/hw/misc/ivshmem.c
@@ -898,9 +898,7 @@ static void ivshmem_common_realize(PCIDevice *dev, Error **errp)
     if (!ivshmem_is_master(s)) {
         error_setg(&s->migration_blocker,
                    "Migration is disabled when using feature 'peer mode' in device 'ivshmem'");
-        migrate_add_blocker(s->migration_blocker, &err);
-        if (err) {
-            error_propagate(errp, err);
+        if (migrate_add_blocker(s->migration_blocker, errp) < 0) {
             error_free(s->migration_blocker);
             return;
         }

diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
index c1b012aea40e2c146e4f68313ec5454fc17fe535..13b05af29bc18a6266f2b9f1dc62f40bb6f7b247 100644 (file)
--- a/hw/scsi/vhost-scsi.c
+++ b/hw/scsi/vhost-scsi.c
@@ -207,9 +207,7 @@ static void vhost_scsi_realize(DeviceState *dev, Error **errp)
                 "When external environment supports it (Orchestrator migrates "
                 "target SCSI device state or use shared storage over network), "
                 "set 'migratable' property to true to enable migration.");
-        migrate_add_blocker(vsc->migration_blocker, &err);
-        if (err) {
-            error_propagate(errp, err);
+        if (migrate_add_blocker(vsc->migration_blocker, errp) < 0) {
             error_free(vsc->migration_blocker);
             goto free_virtio;
         }