[v11,7/8] nbd: introduce ERRP_AUTO_PROPAGATE
diff mbox series

Message ID 20200703090816.3295-8-vsementsov@virtuozzo.com
State New
Headers show
Series
  • error: auto propagated local_err part I
Related show

Commit Message

Vladimir Sementsov-Ogievskiy July 3, 2020, 9:08 a.m. UTC
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 == &error_fatal
(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 then 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_fatal, this means that we don't break error_abort
   (we'll abort on error_set, not on error_propagate)

This commit is generated by command

    sed -n '/^Network Block Device (NBD)$/,/^$/{s/^F: //p}' \
        MAINTAINERS | \
    xargs git ls-files | grep '\.[hc]$' | \
    xargs spatch \
        --sp-file scripts/coccinelle/auto-propagated-errp.cocci \
        --macro-file scripts/cocci-macro-file.h \
        --in-place --no-show-diff --max-width 80

Reported-by: Kevin Wolf <kwolf@redhat.com>
Reported-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 include/block/nbd.h | 1 +
 block/nbd.c         | 7 +++----
 nbd/client.c        | 5 +++++
 nbd/server.c        | 5 +++++
 4 files changed, 14 insertions(+), 4 deletions(-)

Comments

Markus Armbruster July 6, 2020, 5:22 a.m. UTC | #1
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> writes:

> 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 == &error_fatal
> (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 then 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_fatal, this means that we don't break error_abort
>    (we'll abort on error_set, not on error_propagate)
>
> This commit is generated by command
>
>     sed -n '/^Network Block Device (NBD)$/,/^$/{s/^F: //p}' \
>         MAINTAINERS | \
>     xargs git ls-files | grep '\.[hc]$' | \
>     xargs spatch \
>         --sp-file scripts/coccinelle/auto-propagated-errp.cocci \
>         --macro-file scripts/cocci-macro-file.h \
>         --in-place --no-show-diff --max-width 80
>
> Reported-by: Kevin Wolf <kwolf@redhat.com>
> Reported-by: Greg Kurz <groug@kaod.org>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Reviewed-by: Markus Armbruster <armbru@redhat.com>
Markus Armbruster July 7, 2020, 11:51 a.m. UTC | #2
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> writes:

> 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 == &error_fatal

Same for &error_abort, but to fix that, ERRP_AUTO_PROPAGATE() would have
to compromise stack backtraces, so it doesn't.

> (the program will exit prior to the error_append_hint() or
> error_prepend() call).  Fix such cases.

Unclear what exactly is being fixed here, if anything.  What are the
cases?  Can they happen?

The following look like possible cases: nbd_read(),
nbd_send_option_request(), nbd_handle_reply_err(), nbd_opt_info_or_go(),
nbd_start_negotiate(), nbd_receive_negotiate(),
nbd_negotiate_send_rep_verr(), nbd_negotiate_send_rep_list(),
nbd_negotiate_handle_export_name(), nbd_negotiate(),
nbd_export_remove().

Additionally in PATCH 6, v9fs_device_realize_common().

Nothing in PATCH 3+4+5+8 as far as I can tell.

If we lack the time to provide a complete assessment in the commit
messages, let's say so there.

> If we want to check error after errp-function call, we need to
> introduce local_err and then 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_fatal, this means that we don't break error_abort
>    (we'll abort on error_set, not on error_propagate)

Direct use of @errp improves behavior when the argument is
&error_abort.  Worth mentioning, I think.

>
> This commit is generated by command
>
>     sed -n '/^Network Block Device (NBD)$/,/^$/{s/^F: //p}' \
>         MAINTAINERS | \
>     xargs git ls-files | grep '\.[hc]$' | \
>     xargs spatch \
>         --sp-file scripts/coccinelle/auto-propagated-errp.cocci \
>         --macro-file scripts/cocci-macro-file.h \
>         --in-place --no-show-diff --max-width 80
>
> Reported-by: Kevin Wolf <kwolf@redhat.com>
> Reported-by: Greg Kurz <groug@kaod.org>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Patch
diff mbox series

diff --git a/include/block/nbd.h b/include/block/nbd.h
index 20363280ae..f7d87636d3 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -361,6 +361,7 @@  void nbd_server_start_options(NbdServerOptions *arg, Error **errp);
 static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
                            const char *desc, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     int ret = qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
 
     if (ret < 0) {
diff --git a/block/nbd.c b/block/nbd.c
index 6876da04a7..b7cea0f650 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -1408,16 +1408,15 @@  static void nbd_client_close(BlockDriverState *bs)
 static QIOChannelSocket *nbd_establish_connection(SocketAddress *saddr,
                                                   Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     QIOChannelSocket *sioc;
-    Error *local_err = NULL;
 
     sioc = qio_channel_socket_new();
     qio_channel_set_name(QIO_CHANNEL(sioc), "nbd-client");
 
-    qio_channel_socket_connect_sync(sioc, saddr, &local_err);
-    if (local_err) {
+    qio_channel_socket_connect_sync(sioc, saddr, errp);
+    if (*errp) {
         object_unref(OBJECT(sioc));
-        error_propagate(errp, local_err);
         return NULL;
     }
 
diff --git a/nbd/client.c b/nbd/client.c
index ba173108ba..e258ef3f7e 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -68,6 +68,7 @@  static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt,
                                    uint32_t len, const char *data,
                                    Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     NBDOption req;
     QEMU_BUILD_BUG_ON(sizeof(req) != 16);
 
@@ -153,6 +154,7 @@  static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
 static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
                                 bool strict, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     g_autofree char *msg = NULL;
 
     if (!(reply->type & (1 << 31))) {
@@ -337,6 +339,7 @@  static int nbd_receive_list(QIOChannel *ioc, char **name, char **description,
 static int nbd_opt_info_or_go(QIOChannel *ioc, uint32_t opt,
                               NBDExportInfo *info, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     NBDOptionReply reply;
     uint32_t len = strlen(info->name);
     uint16_t type;
@@ -882,6 +885,7 @@  static int nbd_start_negotiate(AioContext *aio_context, QIOChannel *ioc,
                                bool structured_reply, bool *zeroes,
                                Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     uint64_t magic;
 
     trace_nbd_start_negotiate(tlscreds, hostname ? hostname : "<null>");
@@ -1017,6 +1021,7 @@  int nbd_receive_negotiate(AioContext *aio_context, QIOChannel *ioc,
                           const char *hostname, QIOChannel **outioc,
                           NBDExportInfo *info, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     int result;
     bool zeroes;
     bool base_allocation = info->base_allocation;
diff --git a/nbd/server.c b/nbd/server.c
index 20754e9ebc..8a12e586d7 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -211,6 +211,7 @@  static int GCC_FMT_ATTR(4, 0)
 nbd_negotiate_send_rep_verr(NBDClient *client, uint32_t type,
                             Error **errp, const char *fmt, va_list va)
 {
+    ERRP_AUTO_PROPAGATE();
     g_autofree char *msg = NULL;
     int ret;
     size_t len;
@@ -382,6 +383,7 @@  static int nbd_opt_read_name(NBDClient *client, char **name, uint32_t *length,
 static int nbd_negotiate_send_rep_list(NBDClient *client, NBDExport *exp,
                                        Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     size_t name_len, desc_len;
     uint32_t len;
     const char *name = exp->name ? exp->name : "";
@@ -445,6 +447,7 @@  static void nbd_check_meta_export(NBDClient *client)
 static int nbd_negotiate_handle_export_name(NBDClient *client, bool no_zeroes,
                                             Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     g_autofree char *name = NULL;
     char buf[NBD_REPLY_EXPORT_NAME_SIZE] = "";
     size_t len;
@@ -1289,6 +1292,7 @@  static int nbd_negotiate_options(NBDClient *client, Error **errp)
  */
 static coroutine_fn int nbd_negotiate(NBDClient *client, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     char buf[NBD_OLDSTYLE_NEGOTIATE_SIZE] = "";
     int ret;
 
@@ -1663,6 +1667,7 @@  void nbd_export_close(NBDExport *exp)
 
 void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     if (mode == NBD_SERVER_REMOVE_MODE_HARD || QTAILQ_EMPTY(&exp->clients)) {
         nbd_export_close(exp);
         return;