[PATCH hci-8.0 v2 1/3] chardev: implement cpr_claim_fds() in the base class #VSTOR-148304

["Denis V. Lunev" <den@openvz.org>]

From: Denis V. Lunev <den@openvz.org>

Give TYPE_CHARDEV an empty cpr_claim_fds() and make the file, pty and
socket backends chain to their parent's. Every chardev class then has
the hook, so qmp_chardev_change() calls it without a NULL check, and
state owned by the base class can be re-claimed there as well.

No functional change.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
 chardev/char-file.c    |  3 +++
 chardev/char-pty.c     |  3 +++
 chardev/char-socket.c  |  3 +++
 chardev/char.c         | 13 +++++++------
 include/chardev/char.h |  5 ++++-
 5 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/chardev/char-file.c b/chardev/char-file.c
index a90f4a77e13..89011f52e3e 100644
--- a/chardev/char-file.c
+++ b/chardev/char-file.c
@@ -124,7 +124,10 @@ out_close:
 static void char_file_cpr_claim_fds(Chardev *chr)
 {
     FDChardev *s = FD_CHARDEV(chr);
+    ChardevClass *pc = CHARDEV_CLASS(
+        object_class_get_parent(object_class_by_name(TYPE_CHARDEV_FILE)));
 
+    pc->cpr_claim_fds(chr);
     if (s->ioc_out) {
         cpr_delete_fd(chr->label, 0);
         cpr_save_fd(chr->label, 0, QIO_CHANNEL_FILE(s->ioc_out)->fd);
diff --git a/chardev/char-pty.c b/chardev/char-pty.c
index a0090e4c3d1..8058da92bb4 100644
--- a/chardev/char-pty.c
+++ b/chardev/char-pty.c
@@ -403,7 +403,10 @@ static void char_pty_open(Chardev *chr,
 static void char_pty_cpr_claim_fds(Chardev *chr)
 {
     PtyChardev *s = PTY_CHARDEV(chr);
+    ChardevClass *pc = CHARDEV_CLASS(
+        object_class_get_parent(object_class_by_name(TYPE_CHARDEV_PTY)));
 
+    pc->cpr_claim_fds(chr);
     if (s->ioc) {
         cpr_delete_fd(chr->label, 0);
         cpr_save_fd(chr->label, 0, QIO_CHANNEL_FILE(s->ioc)->fd);
diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index d20aea764f9..c73a3dd0f7a 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -1681,7 +1681,10 @@ char_socket_get_connected(Object *obj, Error **errp)
 static void char_socket_cpr_claim_fds(Chardev *chr)
 {
     SocketChardev *s = SOCKET_CHARDEV(chr);
+    ChardevClass *pc = CHARDEV_CLASS(
+        object_class_get_parent(object_class_by_name(TYPE_CHARDEV_SOCKET)));
 
+    pc->cpr_claim_fds(chr);
     if (s->sioc) {
         cpr_delete_fd(chr->label, CPR_CONNSOCK_ID);
         cpr_save_fd(chr->label, CPR_CONNSOCK_ID, s->sioc->fd);
diff --git a/chardev/char.c b/chardev/char.c
index 87f40d0137e..b64767f574e 100644
--- a/chardev/char.c
+++ b/chardev/char.c
@@ -295,12 +295,17 @@ static int null_chr_write(Chardev *chr, const uint8_t *buf, int len)
     return len;
 }
 
+static void char_cpr_claim_fds(Chardev *chr)
+{
+}
+
 static void char_class_init(ObjectClass *oc, const void *data)
 {
     ChardevClass *cc = CHARDEV_CLASS(oc);
 
     cc->chr_write = null_chr_write;
     cc->chr_be_event = chr_be_event;
+    cc->cpr_claim_fds = char_cpr_claim_fds;
 }
 
 static void char_finalize(Object *obj)
@@ -1164,9 +1169,7 @@ ChardevReturn *qmp_chardev_change(const char *id, ChardevBackend *backend,
                           backend, chr->gcontext, handover_yank_instance, errp);
     if (!chr_new) {
         /* the failed replacement's open() may have displaced our cpr fds */
-        if (cc->cpr_claim_fds) {
-            cc->cpr_claim_fds(chr);
-        }
+        cc->cpr_claim_fds(chr);
         return NULL;
     }
 
@@ -1186,9 +1189,7 @@ ChardevReturn *qmp_chardev_change(const char *id, ChardevBackend *backend,
             qemu_chr_be_event(chr, CHR_EVENT_OPENED);
         }
         /* chr_new's open() may have displaced our cpr fds; re-claim them */
-        if (cc->cpr_claim_fds) {
-            cc->cpr_claim_fds(chr);
-        }
+        cc->cpr_claim_fds(chr);
         object_unref(OBJECT(chr_new));
         return NULL;
     }
diff --git a/include/chardev/char.h b/include/chardev/char.h
index 431d07ad3c6..968766fd5d5 100644
--- a/include/chardev/char.h
+++ b/include/chardev/char.h
@@ -305,7 +305,10 @@ struct ChardevClass {
     /* notify the backend of frontend open state */
     void (*chr_set_fe_open)(Chardev *chr, int fe_open);
 
-    /* (re-)register the backend's CPR fds, e.g. on a failed chardev-change */
+    /*
+     * (re-)register CPR fds, e.g. on a failed chardev-change; an override
+     * must call the parent's hook first
+     */
     void (*cpr_claim_fds)(Chardev *chr);
 
     /* handle various events */
-- 
2.53.0