[RFC v5 087/126] Migration: introduce ERRP_AUTO_PROPAGATE

[Vladimir Sementsov-Ogievskiy]

If we want to add some info to errp (by error_prepend() or
error_append_hint()), we must use the ERRP_AUTO_PROPAGATE macro.
Otherwise, this info will not be added when errp == &fatal_err
(the program will exit prior to the error_append_hint() or
error_prepend() call).  Fix such cases.

If we want to check error after errp-function call, we need to
introduce local_err and than propagate it to errp. Instead, use
ERRP_AUTO_PROPAGATE macro, benefits are:
1. No need of explicit error_propagate call
2. No need of explicit local_err variable: use errp directly
3. ERRP_AUTO_PROPAGATE leaves errp as is if it's not NULL or
   &error_fatel, this means that we don't break error_abort
   (we'll abort on error_set, not on error_propagate)

This commit (together with its neighbors) was generated by

for f in $(git grep -l errp \*.[ch]); do \
    spatch --sp-file scripts/coccinelle/auto-propagated-errp.cocci \
    --macro-file scripts/cocci-macro-file.h --in-place --no-show-diff $f; \
done;

then fix a bit of compilation problems: coccinelle for some reason
leaves several
f() {
    ...
    goto out;
    ...
    out:
}
patterns, with "out:" at function end.

then
./python/commit-per-subsystem.py MAINTAINERS "$(< auto-msg)"

(auto-msg was a file with this commit message)

Still, for backporting it may be more comfortable to use only the first
command and then do one huge commit.

Reported-by: Kevin Wolf <address@hidden>
Reported-by: Greg Kurz <address@hidden>
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 migration/migration.c | 39 ++++++++++++++++++---------------------
 migration/ram.c       | 13 ++++++-------
 migration/rdma.c      | 13 ++++++-------
 migration/savevm.c    |  2 ++
 migration/socket.c    | 18 ++++++++----------
 5 files changed, 40 insertions(+), 45 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 5f7e4d15e9..36a0b9e783 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -583,6 +583,7 @@ void migration_fd_process_incoming(QEMUFile *f)
 
 void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     MigrationIncomingState *mis = migration_incoming_get_current();
     bool start_migration;
 
@@ -603,12 +604,10 @@ void migration_ioc_process_incoming(QIOChannel *ioc, 
Error **errp)
          */
         start_migration = !migrate_use_multifd();
     } else {
-        Error *local_err = NULL;
         /* Multiple connections */
         assert(migrate_use_multifd());
-        start_migration = multifd_recv_new_channel(ioc, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        start_migration = multifd_recv_new_channel(ioc, errp);
+        if (*errp) {
             return;
         }
     }
@@ -971,6 +970,7 @@ static bool migrate_caps_check(bool *cap_list,
                                MigrationCapabilityStatusList *params,
                                Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     MigrationCapabilityStatusList *cap;
     bool old_postcopy_cap;
     MigrationIncomingState *mis = migration_incoming_get_current();
@@ -1764,7 +1764,7 @@ void migrate_del_blocker(Error *reason)
 
 void qmp_migrate_incoming(const char *uri, Error **errp)
 {
-    Error *local_err = NULL;
+    ERRP_AUTO_PROPAGATE();
     static bool once = true;
 
     if (!deferred_incoming) {
@@ -1775,10 +1775,9 @@ void qmp_migrate_incoming(const char *uri, Error **errp)
         error_setg(errp, "The incoming migration has already been started");
     }
 
-    qemu_start_incoming_migration(uri, &local_err);
+    qemu_start_incoming_migration(uri, errp);
 
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (*errp) {
         return;
     }
 
@@ -1856,7 +1855,7 @@ bool migration_is_blocked(Error **errp)
 static bool migrate_prepare(MigrationState *s, bool blk, bool blk_inc,
                             bool resume, Error **errp)
 {
-    Error *local_err = NULL;
+    ERRP_AUTO_PROPAGATE();
 
     if (resume) {
         if (s->state != MIGRATION_STATUS_POSTCOPY_PAUSED) {
@@ -1909,9 +1908,8 @@ static bool migrate_prepare(MigrationState *s, bool blk, 
bool blk_inc,
                        "current migration capabilities");
             return false;
         }
-        migrate_set_block_enabled(true, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        migrate_set_block_enabled(true, errp);
+        if (*errp) {
             return false;
         }
         s->must_remove_block_options = true;
@@ -1935,7 +1933,7 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
                  bool has_inc, bool inc, bool has_detach, bool detach,
                  bool has_resume, bool resume, Error **errp)
 {
-    Error *local_err = NULL;
+    ERRP_AUTO_PROPAGATE();
     MigrationState *s = migrate_get_current();
     const char *p;
 
@@ -1946,17 +1944,17 @@ void qmp_migrate(const char *uri, bool has_blk, bool 
blk,
     }
 
     if (strstart(uri, "tcp:", &p)) {
-        tcp_start_outgoing_migration(s, p, &local_err);
+        tcp_start_outgoing_migration(s, p, errp);
 #ifdef CONFIG_RDMA
     } else if (strstart(uri, "rdma:", &p)) {
-        rdma_start_outgoing_migration(s, p, &local_err);
+        rdma_start_outgoing_migration(s, p, errp);
 #endif
     } else if (strstart(uri, "exec:", &p)) {
-        exec_start_outgoing_migration(s, p, &local_err);
+        exec_start_outgoing_migration(s, p, errp);
     } else if (strstart(uri, "unix:", &p)) {
-        unix_start_outgoing_migration(s, p, &local_err);
+        unix_start_outgoing_migration(s, p, errp);
     } else if (strstart(uri, "fd:", &p)) {
-        fd_start_outgoing_migration(s, p, &local_err);
+        fd_start_outgoing_migration(s, p, errp);
     } else {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "uri",
                    "a valid migration protocol");
@@ -1966,9 +1964,8 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
         return;
     }
 
-    if (local_err) {
-        migrate_fd_error(s, local_err);
-        error_propagate(errp, local_err);
+    if (*errp) {
+        migrate_fd_error(s, *errp);
         return;
     }
 }
diff --git a/migration/ram.c b/migration/ram.c
index 22423f08cd..0100c11dd7 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1474,14 +1474,14 @@ bool multifd_recv_all_channels_created(void)
  */
 bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     MultiFDRecvParams *p;
-    Error *local_err = NULL;
     int id;
 
-    id = multifd_recv_initial_packet(ioc, &local_err);
+    id = multifd_recv_initial_packet(ioc, errp);
     if (id < 0) {
-        multifd_recv_terminate_threads(local_err);
-        error_propagate_prepend(errp, local_err,
+        multifd_recv_terminate_threads(*errp);
+        error_prepend(errp,
                                 "failed to receive packet"
                                 " via multifd channel %d: ",
                                 atomic_read(&multifd_recv_state->count));
@@ -1491,10 +1491,9 @@ bool multifd_recv_new_channel(QIOChannel *ioc, Error 
**errp)
 
     p = &multifd_recv_state->params[id];
     if (p->c != NULL) {
-        error_setg(&local_err, "multifd: received id '%d' already setup'",
+        error_setg(errp, "multifd: received id '%d' already setup'",
                    id);
-        multifd_recv_terminate_threads(local_err);
-        error_propagate(errp, local_err);
+        multifd_recv_terminate_threads(*errp);
         return false;
     }
     p->c = ioc;
diff --git a/migration/rdma.c b/migration/rdma.c
index 4c74e88a37..db985fee73 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -2396,8 +2396,9 @@ static void qemu_rdma_cleanup(RDMAContext *rdma)
 
 static int qemu_rdma_source_init(RDMAContext *rdma, bool pin_all, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     int ret, idx;
-    Error *local_err = NULL, **temp = &local_err;
+    Error **temp = errp;
 
     /*
      * Will be validated against destination's actual capabilities
@@ -2450,7 +2451,6 @@ static int qemu_rdma_source_init(RDMAContext *rdma, bool 
pin_all, Error **errp)
     return 0;
 
 err_rdma_source_init:
-    error_propagate(errp, local_err);
     qemu_rdma_cleanup(rdma);
     return -1;
 }
@@ -4044,18 +4044,18 @@ static void rdma_accept_incoming_migration(void *opaque)
 
 void rdma_start_incoming_migration(const char *host_port, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     int ret;
     RDMAContext *rdma, *rdma_return_path = NULL;
-    Error *local_err = NULL;
 
     trace_rdma_start_incoming_migration();
-    rdma = qemu_rdma_data_init(host_port, &local_err);
+    rdma = qemu_rdma_data_init(host_port, errp);
 
     if (rdma == NULL) {
         goto err;
     }
 
-    ret = qemu_rdma_dest_init(rdma, &local_err);
+    ret = qemu_rdma_dest_init(rdma, errp);
 
     if (ret) {
         goto err;
@@ -4074,7 +4074,7 @@ void rdma_start_incoming_migration(const char *host_port, 
Error **errp)
 
     /* initialize the RDMAContext for return path */
     if (migrate_postcopy()) {
-        rdma_return_path = qemu_rdma_data_init(host_port, &local_err);
+        rdma_return_path = qemu_rdma_data_init(host_port, errp);
 
         if (rdma_return_path == NULL) {
             goto err;
@@ -4087,7 +4087,6 @@ void rdma_start_incoming_migration(const char *host_port, 
Error **errp)
                         NULL, (void *)(intptr_t)rdma);
     return;
 err:
-    error_propagate(errp, local_err);
     g_free(rdma);
     g_free(rdma_return_path);
 }
diff --git a/migration/savevm.c b/migration/savevm.c
index bb9462a54d..f9293fe192 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2586,6 +2586,7 @@ int qemu_load_device_state(QEMUFile *f)
 
 int save_snapshot(const char *name, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     BlockDriverState *bs, *bs1;
     QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
     int ret = -1;
@@ -2790,6 +2791,7 @@ void qmp_xen_load_devices_state(const char *filename, 
Error **errp)
 
 int load_snapshot(const char *name, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     BlockDriverState *bs, *bs_vm_state;
     QEMUSnapshotInfo sn;
     QEMUFile *f;
diff --git a/migration/socket.c b/migration/socket.c
index 97c9efde59..bc07ef92a1 100644
--- a/migration/socket.c
+++ b/migration/socket.c
@@ -139,12 +139,11 @@ void tcp_start_outgoing_migration(MigrationState *s,
                                   const char *host_port,
                                   Error **errp)
 {
-    Error *err = NULL;
-    SocketAddress *saddr = tcp_build_address(host_port, &err);
-    if (!err) {
-        socket_start_outgoing_migration(s, saddr, &err);
+    ERRP_AUTO_PROPAGATE();
+    SocketAddress *saddr = tcp_build_address(host_port, errp);
+    if (!*errp) {
+        socket_start_outgoing_migration(s, saddr, errp);
     }
-    error_propagate(errp, err);
 }
 
 void unix_start_outgoing_migration(MigrationState *s,
@@ -209,13 +208,12 @@ static void socket_start_incoming_migration(SocketAddress 
*saddr,
 
 void tcp_start_incoming_migration(const char *host_port, Error **errp)
 {
-    Error *err = NULL;
-    SocketAddress *saddr = tcp_build_address(host_port, &err);
-    if (!err) {
-        socket_start_incoming_migration(saddr, &err);
+    ERRP_AUTO_PROPAGATE();
+    SocketAddress *saddr = tcp_build_address(host_port, errp);
+    if (!*errp) {
+        socket_start_incoming_migration(saddr, errp);
     }
     qapi_free_SocketAddress(saddr);
-    error_propagate(errp, err);
 }
 
 void unix_start_incoming_migration(const char *path, Error **errp)
-- 
2.21.0