[Qemu-devel] [PATCH 18/38] char: replace qemu_chr_claim/release with qemu_chr_fe_init/deinit

[Marc-André Lureau]

Now that all front end use qemu_chr_fe_init(), we can move chardev
claiming in init(), and add a function deinit() to release the chardev
and cleanup handlers.

The qemu_chr_fe_claim_no_fail() for property are gone, since the
property will raise an error instead. In other cases, where there is
already an error path, an error is raised instead. Finally, other cases
are handled by &error_abort in qemu_chr_fe_init().

Signed-off-by: Marc-André Lureau <address@hidden>
---
 backends/rng-egd.c               | 10 +---------
 gdbstub.c                        |  3 +--
 hw/arm/pxa2xx.c                  |  1 -
 hw/char/mcf_uart.c               |  1 -
 hw/char/serial.c                 |  2 +-
 hw/char/sh_serial.c              |  1 -
 hw/char/xen_console.c            | 16 +++------------
 hw/core/qdev-properties-system.c | 14 +++++---------
 hw/usb/ccid-card-passthru.c      |  1 +
 hw/usb/redirect.c                |  2 +-
 monitor.c                        |  4 +---
 net/colo-compare.c               | 20 +++----------------
 net/filter-mirror.c              | 20 +++----------------
 net/slirp.c                      |  1 -
 net/vhost-user.c                 |  8 ++------
 qemu-char.c                      | 42 +++++++++++++++++-----------------------
 tests/vhost-user-test.c          |  1 +
 vl.c                             |  1 -
 include/sysemu/char.h            | 39 +++++++++----------------------------
 19 files changed, 50 insertions(+), 137 deletions(-)

diff --git a/backends/rng-egd.c b/backends/rng-egd.c
index d9e50bb..433f583 100644
--- a/backends/rng-egd.c
+++ b/backends/rng-egd.c
@@ -100,10 +100,6 @@ static void rng_egd_opened(RngBackend *b, Error **errp)
                   "Device '%s' not found", s->chr_name);
         return;
     }
-    if (qemu_chr_fe_claim(chr) != 0) {
-        error_setg(errp, QERR_DEVICE_IN_USE, s->chr_name);
-        return;
-    }
     if (!qemu_chr_fe_init(&s->chr, chr, errp)) {
         return;
     }
@@ -149,11 +145,7 @@ static void rng_egd_finalize(Object *obj)
 {
     RngEgd *s = RNG_EGD(obj);
 
-    if (s->chr.chr) {
-        qemu_chr_fe_set_handlers(&s->chr, NULL, NULL, NULL, NULL, NULL);
-        qemu_chr_fe_release(s->chr.chr);
-    }
-
+    qemu_chr_fe_deinit(&s->chr);
     g_free(s->chr_name);
 }
 
diff --git a/gdbstub.c b/gdbstub.c
index 33b056e..5944494 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -1494,6 +1494,7 @@ void gdb_exit(CPUArchState *env, int code)
   put_packet(s, buf);
 
 #ifndef CONFIG_USER_ONLY
+  qemu_chr_fe_deinit(&s->chr);
   qemu_chr_delete(chr);
 #endif
 }
@@ -1752,8 +1753,6 @@ int gdbserver_start(const char *device)
         chr = qemu_chr_new_noreplay("gdb", device);
         if (!chr)
             return -1;
-
-        qemu_chr_fe_claim_no_fail(chr);
     }
 
     s = gdbserver_state;
diff --git a/hw/arm/pxa2xx.c b/hw/arm/pxa2xx.c
index 798c05b..cd98379 100644
--- a/hw/arm/pxa2xx.c
+++ b/hw/arm/pxa2xx.c
@@ -1976,7 +1976,6 @@ static void pxa2xx_fir_realize(DeviceState *dev, Error 
**errp)
     PXA2xxFIrState *s = PXA2XX_FIR(dev);
 
     if (s->chr.chr) {
-        qemu_chr_fe_claim_no_fail(s->chr.chr);
         qemu_chr_fe_set_handlers(&s->chr, pxa2xx_fir_is_empty,
                                  pxa2xx_fir_rx, pxa2xx_fir_event, s, NULL);
     }
diff --git a/hw/char/mcf_uart.c b/hw/char/mcf_uart.c
index cc3db13..b505343 100644
--- a/hw/char/mcf_uart.c
+++ b/hw/char/mcf_uart.c
@@ -285,7 +285,6 @@ void *mcf_uart_init(qemu_irq irq, CharDriverState *chr)
     s->irq = irq;
     if (chr) {
         qemu_chr_fe_init(&s->chr, chr, &error_abort);
-        qemu_chr_fe_claim_no_fail(chr);
         qemu_chr_fe_set_handlers(&s->chr, mcf_uart_can_receive,
                                  mcf_uart_receive, mcf_uart_event, s, NULL);
     }
diff --git a/hw/char/serial.c b/hw/char/serial.c
index 257be46..afa6248 100644
--- a/hw/char/serial.c
+++ b/hw/char/serial.c
@@ -904,7 +904,7 @@ void serial_realize_core(SerialState *s, Error **errp)
 
 void serial_exit_core(SerialState *s)
 {
-    qemu_chr_fe_set_handlers(&s->chr, NULL, NULL, NULL, NULL, NULL);
+    qemu_chr_fe_deinit(&s->chr);
     qemu_unregister_reset(serial_reset, s);
 }
 
diff --git a/hw/char/sh_serial.c b/hw/char/sh_serial.c
index 8d82986..8bb45db 100644
--- a/hw/char/sh_serial.c
+++ b/hw/char/sh_serial.c
@@ -397,7 +397,6 @@ void sh_serial_init(MemoryRegion *sysmem,
     memory_region_add_subregion(sysmem, A7ADDR(base), &s->iomem_a7);
 
     if (chr) {
-        qemu_chr_fe_claim_no_fail(chr);
         qemu_chr_fe_init(&s->chr, chr, &error_abort);
         qemu_chr_fe_set_handlers(&s->chr, sh_serial_can_receive1,
                                  sh_serial_receive1,
diff --git a/hw/char/xen_console.c b/hw/char/xen_console.c
index 5e5aca1..f664366 100644
--- a/hw/char/xen_console.c
+++ b/hw/char/xen_console.c
@@ -245,15 +245,8 @@ static int con_initialise(struct XenDevice *xendev)
 
     xen_be_bind_evtchn(&con->xendev);
     if (con->chr.chr) {
-        if (qemu_chr_fe_claim(con->chr.chr) == 0) {
-            qemu_chr_fe_set_handlers(&con->chr, xencons_can_receive,
-                                     xencons_receive, NULL, con, NULL);
-        } else {
-            xen_be_printf(xendev, 0,
-                          "xen_console_init error chardev %s already used\n",
-                          con->chr.chr->label);
-            con->chr.chr = NULL;
-        }
+        qemu_chr_fe_set_handlers(&con->chr, xencons_can_receive,
+                                 xencons_receive, NULL, con, NULL);
     }
 
     xen_be_printf(xendev, 1, "ring mfn %d, remote port %d, local port %d, 
limit %zd\n",
@@ -268,10 +261,7 @@ static void con_disconnect(struct XenDevice *xendev)
 {
     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 
-    if (con->chr.chr) {
-        qemu_chr_fe_set_handlers(&con->chr, NULL, NULL, NULL, NULL, NULL);
-        qemu_chr_fe_release(con->chr.chr);
-    }
+    qemu_chr_fe_deinit(&con->chr);
     xen_be_unbind_evtchn(&con->xendev);
 
     if (con->sring) {
diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index 6d45d32..c35f0f5 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -206,13 +206,12 @@ static void set_chr(Object *obj, Visitor *v, const char 
*name, void *opaque,
                    object_get_typename(obj), prop->name, str);
         return;
     }
-    if (qemu_chr_fe_claim(s) != 0) {
-        error_setg(errp, "Property '%s.%s' can't take value '%s', it's in use",
-                  object_get_typename(obj), prop->name, str);
+
+    if (!qemu_chr_fe_init(be, s, errp)) {
+        error_prepend(errp, "Property '%s.%s' can't take value '%s': ",
+                      object_get_typename(obj), prop->name, str);
         return;
     }
-
-    qemu_chr_fe_init(be, s, errp);
 }
 
 static void release_chr(Object *obj, const char *name, void *opaque)
@@ -221,10 +220,7 @@ static void release_chr(Object *obj, const char *name, 
void *opaque)
     Property *prop = opaque;
     CharBackend *be = qdev_get_prop_ptr(dev, prop);
 
-    if (be->chr) {
-        qemu_chr_fe_set_handlers(be, NULL, NULL, NULL, NULL, NULL);
-        qemu_chr_fe_release(be->chr);
-    }
+    qemu_chr_fe_deinit(be);
 }
 
 PropertyInfo qdev_prop_chr = {
diff --git a/hw/usb/ccid-card-passthru.c b/hw/usb/ccid-card-passthru.c
index a8c8684..369a8f1 100644
--- a/hw/usb/ccid-card-passthru.c
+++ b/hw/usb/ccid-card-passthru.c
@@ -266,6 +266,7 @@ static void ccid_card_vscard_drop_connection(PassthruState 
*card)
 {
     CharDriverState *chr = qemu_chr_fe_get_driver(&card->cs);
 
+    qemu_chr_fe_deinit(&card->cs);
     qemu_chr_delete(chr);
     card->vscard_in_pos = card->vscard_in_hdr = 0;
 }
diff --git a/hw/usb/redirect.c b/hw/usb/redirect.c
index 0fb2e9a..6f5ad20 100644
--- a/hw/usb/redirect.c
+++ b/hw/usb/redirect.c
@@ -1430,9 +1430,9 @@ static void usbredir_handle_destroy(USBDevice *udev)
     USBRedirDevice *dev = USB_REDIRECT(udev);
     CharDriverState *chr = qemu_chr_fe_get_driver(&dev->cs);
 
+    qemu_chr_fe_deinit(&dev->cs);
     qemu_chr_delete(chr);
 
-    dev->cs.chr = NULL;
     /* Note must be done after qemu_chr_close, as that causes a close event */
     qemu_bh_delete(dev->chardev_close_bh);
     qemu_bh_delete(dev->device_reject_bh);
diff --git a/monitor.c b/monitor.c
index 1c6f28f..5c349c5 100644
--- a/monitor.c
+++ b/monitor.c
@@ -582,9 +582,7 @@ static void monitor_data_init(Monitor *mon)
 
 static void monitor_data_destroy(Monitor *mon)
 {
-    if (mon->chr.chr) {
-        qemu_chr_fe_set_handlers(&mon->chr, NULL, NULL, NULL, NULL, NULL);
-    }
+    qemu_chr_fe_deinit(&mon->chr);
     if (monitor_is_qmp(mon)) {
         json_message_parser_destroy(&mon->qmp.parser);
     }
diff --git a/net/colo-compare.c b/net/colo-compare.c
index 63d92cb..3083681 100644
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -590,12 +590,6 @@ static int find_and_check_chardev(CharDriverState **chr,
         return 1;
     }
 
-    if (qemu_chr_fe_claim(*chr) < 0) {
-        error_setg(errp, "chardev \"%s\" cannot be claimed",
-                   chr_name);
-        return 1;
-    }
-
     return 0;
 }
 
@@ -707,17 +701,9 @@ static void colo_compare_finalize(Object *obj)
 {
     CompareState *s = COLO_COMPARE(obj);
 
-    if (s->chr_pri_in.chr) {
-        qemu_chr_fe_set_handlers(&s->chr_pri_in, NULL, NULL, NULL, NULL, NULL);
-        qemu_chr_fe_release(s->chr_pri_in.chr);
-    }
-    if (s->chr_sec_in.chr) {
-        qemu_chr_fe_set_handlers(&s->chr_sec_in, NULL, NULL, NULL, NULL, NULL);
-        qemu_chr_fe_release(s->chr_sec_in.chr);
-    }
-    if (s->chr_out.chr) {
-        qemu_chr_fe_release(s->chr_out.chr);
-    }
+    qemu_chr_fe_deinit(&s->chr_pri_in);
+    qemu_chr_fe_deinit(&s->chr_sec_in);
+    qemu_chr_fe_deinit(&s->chr_out);
 
     g_queue_free(&s->conn_list);
 
diff --git a/net/filter-mirror.c b/net/filter-mirror.c
index 12d79cd..1864c81 100644
--- a/net/filter-mirror.c
+++ b/net/filter-mirror.c
@@ -175,22 +175,15 @@ static void filter_mirror_cleanup(NetFilterState *nf)
 {
     MirrorState *s = FILTER_MIRROR(nf);
 
-    if (s->chr_out.chr) {
-        qemu_chr_fe_release(s->chr_out.chr);
-    }
+    qemu_chr_fe_deinit(&s->chr_out);
 }
 
 static void filter_redirector_cleanup(NetFilterState *nf)
 {
     MirrorState *s = FILTER_REDIRECTOR(nf);
 
-    if (s->chr_in.chr) {
-        qemu_chr_fe_set_handlers(&s->chr_in, NULL, NULL, NULL, NULL, NULL);
-        qemu_chr_fe_release(s->chr_in.chr);
-    }
-    if (s->chr_out.chr) {
-        qemu_chr_fe_release(s->chr_out.chr);
-    }
+    qemu_chr_fe_deinit(&s->chr_in);
+    qemu_chr_fe_deinit(&s->chr_out);
 }
 
 static void filter_mirror_setup(NetFilterState *nf, Error **errp)
@@ -211,11 +204,6 @@ static void filter_mirror_setup(NetFilterState *nf, Error 
**errp)
         return;
     }
 
-    if (qemu_chr_fe_claim(chr) != 0) {
-        error_setg(errp, QERR_DEVICE_IN_USE, s->outdev);
-        return;
-    }
-
     qemu_chr_fe_init(&s->chr_out, chr, errp);
 }
 
@@ -254,7 +242,6 @@ static void filter_redirector_setup(NetFilterState *nf, 
Error **errp)
             return;
         }
 
-        qemu_chr_fe_claim_no_fail(chr);
         if (!qemu_chr_fe_init(&s->chr_in, chr, errp)) {
             return;
         }
@@ -271,7 +258,6 @@ static void filter_redirector_setup(NetFilterState *nf, 
Error **errp)
                       "OUT Device '%s' not found", s->outdev);
             return;
         }
-        qemu_chr_fe_claim_no_fail(chr);
         if (!qemu_chr_fe_init(&s->chr_out, chr, errp)) {
             return;
         }
diff --git a/net/slirp.c b/net/slirp.c
index f9f6fc6..0e67535 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -774,7 +774,6 @@ static int slirp_guestfwd(SlirpState *s, const char 
*config_str,
         fwd->port = port;
         fwd->slirp = s->slirp;
 
-        qemu_chr_fe_claim_no_fail(fwd->hd.chr);
         qemu_chr_fe_set_handlers(&fwd->hd, guestfwd_can_read, guestfwd_read,
                                  NULL, fwd, NULL);
     }
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 357b500..140a4e0 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -150,10 +150,8 @@ static void vhost_user_cleanup(NetClientState *nc)
         g_free(s->vhost_net);
         s->vhost_net = NULL;
     }
-    if (nc->queue_index == 0 && s->chr.chr) {
-        qemu_chr_fe_set_handlers(&s->chr, NULL, NULL, NULL, NULL, NULL);
-        qemu_chr_fe_release(s->chr.chr);
-        s->chr.chr = NULL;
+    if (nc->queue_index == 0) {
+        qemu_chr_fe_deinit(&s->chr);
     }
 
     qemu_purge_queued_packets(nc);
@@ -297,8 +295,6 @@ static CharDriverState *net_vhost_claim_chardev(
         return NULL;
     }
 
-    qemu_chr_fe_claim_no_fail(chr);
-
     return chr;
 }
 
diff --git a/qemu-char.c b/qemu-char.c
index 1ed69d0..40c5b50 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -776,6 +776,7 @@ static void mux_chr_close(struct CharDriverState *chr)
 {
     MuxDriver *d = chr->opaque;
 
+    qemu_chr_fe_deinit(&d->chr);
     g_free(d);
 }
 
@@ -876,6 +877,12 @@ bool qemu_chr_fe_init(CharBackend *b, CharDriverState *s, 
Error **errp)
     assert(b);
     assert(s);
 
+    if (s->avail_connections < 1) {
+        error_setg(errp, QERR_DEVICE_IN_USE, s->label);
+        return false;
+    }
+    s->avail_connections--;
+
     if (s->is_mux) {
         tag = mux_chr_new_handler_tag(s, errp);
         if (tag < 0) {
@@ -889,6 +896,17 @@ bool qemu_chr_fe_init(CharBackend *b, CharDriverState *s, 
Error **errp)
     return true;
 }
 
+void qemu_chr_fe_deinit(CharBackend *b)
+{
+    assert(b);
+
+    if (b->chr) {
+        qemu_chr_fe_set_handlers(b, NULL, NULL, NULL, NULL, NULL);
+        b->chr->avail_connections++;
+        b->chr = NULL;
+    }
+}
+
 void qemu_chr_fe_set_handlers(CharBackend *b,
                               IOCanReadHandler *fd_can_read,
                               IOReadHandler *fd_read,
@@ -4124,7 +4142,6 @@ CharDriverState *qemu_chr_new_noreplay(const char *label, 
const char *filename)
         error_report_err(err);
     }
     if (chr && qemu_opt_get_bool(opts, "mux", 0)) {
-        qemu_chr_fe_claim_no_fail(chr);
         monitor_init(chr, MONITOR_USE_READLINE);
     }
     qemu_opts_del(opts);
@@ -4200,29 +4217,6 @@ guint qemu_chr_fe_add_watch(CharBackend *be, 
GIOCondition cond,
     return tag;
 }
 
-int qemu_chr_fe_claim(CharDriverState *s)
-{
-    if (s->avail_connections < 1) {
-        return -1;
-    }
-    s->avail_connections--;
-    return 0;
-}
-
-void qemu_chr_fe_claim_no_fail(CharDriverState *s)
-{
-    if (qemu_chr_fe_claim(s) != 0) {
-        fprintf(stderr, "%s: error chardev \"%s\" already used\n",
-                __func__, s->label);
-        exit(1);
-    }
-}
-
-void qemu_chr_fe_release(CharDriverState *s)
-{
-    s->avail_connections++;
-}
-
 void qemu_chr_fe_disconnect(CharBackend *be)
 {
     CharDriverState *chr = be->chr;
diff --git a/tests/vhost-user-test.c b/tests/vhost-user-test.c
index 2d86de1..24c2323 100644
--- a/tests/vhost-user-test.c
+++ b/tests/vhost-user-test.c
@@ -490,6 +490,7 @@ static gboolean _test_server_free(TestServer *server)
     int i;
     CharDriverState *chr = qemu_chr_fe_get_driver(&server->chr);
 
+    qemu_chr_fe_deinit(&server->chr);
     qemu_chr_delete(chr);
 
     for (i = 0; i < server->fds_num; i++) {
diff --git a/vl.c b/vl.c
index caa5f3b..43f1457 100644
--- a/vl.c
+++ b/vl.c
@@ -2417,7 +2417,6 @@ static int mon_init_func(void *opaque, QemuOpts *opts, 
Error **errp)
         exit(1);
     }
 
-    qemu_chr_fe_claim_no_fail(chr);
     monitor_init(chr, flags);
     return 0;
 }
diff --git a/include/sysemu/char.h b/include/sysemu/char.h
index 6737a8a..b81dbcc 100644
--- a/include/sysemu/char.h
+++ b/include/sysemu/char.h
@@ -361,35 +361,6 @@ int qemu_chr_fe_get_msgfds(CharBackend *be, int *fds, int 
num);
  */
 int qemu_chr_fe_set_msgfds(CharBackend *be, int *fds, int num);
 
-/**
- * @qemu_chr_fe_claim:
- *
- * Claim a backend before using it, should be called before calling
- * qemu_chr_fe_set_handlers().
- *
- * Returns: -1 if the backend is already in use by another frontend, 0 on
- *          success.
- */
-int qemu_chr_fe_claim(CharDriverState *s);
-
-/**
- * @qemu_chr_fe_claim_no_fail:
- *
- * Like qemu_chr_fe_claim, but will exit qemu with an error when the
- * backend is already in use.
- */
-void qemu_chr_fe_claim_no_fail(CharDriverState *s);
-
-/**
- * @qemu_chr_fe_claim:
- *
- * Release a backend for use by another frontend.
- *
- * Returns: -1 if the backend is already in use by another frontend, 0 on
- *          success.
- */
-void qemu_chr_fe_release(CharDriverState *s);
-
 /**
  * @qemu_chr_be_can_write:
  *
@@ -437,7 +408,8 @@ void qemu_chr_be_event(CharDriverState *s, int event);
  * @qemu_chr_fe_init:
  *
  * Initializes a front end for the given CharBackend and
- * CharDriver.
+ * CharDriver. Call qemu_chr_fe_deinit() to remove the association and
+ * release the driver.
  *
  * Returns: false on error.
  */
@@ -450,6 +422,13 @@ bool qemu_chr_fe_init(CharBackend *b, CharDriverState *s, 
Error **errp);
  */
 CharDriverState *qemu_chr_fe_get_driver(CharBackend *be);
 
+/**
+ * @qemu_chr_fe_deinit:
+ *
+ * Dissociate the CharBackend from the CharDriver.
+ */
+void qemu_chr_fe_deinit(CharBackend *b);
+
 /**
  * @qemu_chr_fe_set_handlers:
  * @b: a CharBackend
-- 
2.10.0