monitor: eliminate monitor_is_hmp_non_interactive method

The monitor_is_hmp_non_interactive method is used by
monitor_suspend and monitor_resume, to make them a no-op
if the HMP does not use readline.

There are only a handful of callers of suspend/resume and
they can be made to skip the call when readline is not
present.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Tested-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20260706135824.2623960-23-berrange@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

include/monitor/monitor.h

@@ -37,7 +37,7 @@ int monitor_new(MonitorOptions *opts, bool allow_hmp, Error **errp);
 int monitor_new_opts(QemuOpts *opts, Error **errp);
 void monitor_cleanup(void);
 
-int monitor_suspend(Monitor *mon);
+void monitor_suspend(Monitor *mon);
 void monitor_resume(Monitor *mon);
 
 int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp);

migration/migration-hmp-cmds.c

@@ -19,6 +19,7 @@
 #include "monitor/hmp.h"
 #include "monitor/hmp-completion.h"
 #include "monitor/monitor.h"
+#include "monitor/monitor-internal.h"
 #include "qapi/error.h"
 #include "qapi/qapi-commands-migration.h"
 #include "qapi/qapi-visit-migration.h"
@@ -853,12 +854,14 @@ void hmp_migrate(Monitor *mon, const QDict *qdict)
 
     if (!detach) {
         HMPMigrationStatus *status;
+        MonitorHMP *hmp = MONITOR_HMP(mon);
 
-        if (monitor_suspend(mon) < 0) {
+        if (!hmp->use_readline) {
             monitor_printf(mon, "terminal does not allow synchronous "
                            "migration, continuing detached\n");
             return;
         }
+        monitor_suspend(mon);
 
         status = g_malloc0(sizeof(*status));
         status->mon = mon;

monitor/hmp-cmds.c

@@ -129,7 +129,10 @@ void hmp_info_version(Monitor *mon, const QDict *qdict)
 
 void hmp_quit(Monitor *mon, const QDict *qdict)
 {
-    monitor_suspend(mon);
+    MonitorHMP *hmp = MONITOR_HMP(mon);
+    if (hmp->use_readline) {
+        monitor_suspend(mon);
+    }
     qmp_quit(NULL);
 }
 

monitor/hmp.c

@@ -1528,13 +1528,16 @@ static void monitor_read(void *opaque, const uint8_t *buf, int size)
 static void monitor_event(void *opaque, QEMUChrEvent event)
 {
     Monitor *mon = opaque;
+    MonitorHMP *hmp = MONITOR_HMP(mon);
 
     switch (event) {
     case CHR_EVENT_MUX_IN:
         qemu_mutex_lock(&mon->mon_lock);
         if (mon->mux_out) {
             mon->mux_out = 0;
-            monitor_resume(mon);
+            if (hmp->use_readline) {
+                monitor_resume(mon);
+            }
         }
         qemu_mutex_unlock(&mon->mon_lock);
         break;
@@ -1547,7 +1550,9 @@ static void monitor_event(void *opaque, QEMUChrEvent event)
             } else {
                 monitor_flush_locked(mon);
             }
-            monitor_suspend(mon);
+            if (hmp->use_readline) {
+                monitor_suspend(mon);
+            }
             mon->mux_out = 1;
         }
         qemu_mutex_unlock(&mon->mon_lock);
@@ -1558,7 +1563,7 @@ static void monitor_event(void *opaque, QEMUChrEvent event)
                        "information\n", QEMU_VERSION);
         qemu_mutex_lock(&mon->mon_lock);
         mon->reset_seen = 1;
-        if (!mon->mux_out) {
+        if (!mon->mux_out && hmp->use_readline) {
             /* Suspend-resume forces the prompt to be printed.  */
             monitor_suspend(mon);
             monitor_resume(mon);

monitor/monitor.c

@@ -157,25 +157,6 @@ bool monitor_requires_iothread(const Monitor *mon)
     return cls->requires_iothread && cls->requires_iothread(mon);
 }
 
-/**
- * Is @mon is using readline?
- * Note: not all HMP monitors use readline, e.g., gdbserver has a
- * non-interactive HMP monitor, so readline is not used there.
- */
-static inline bool monitor_uses_readline(const MonitorHMP *mon)
-{
-    return mon->use_readline;
-}
-
-static inline bool monitor_is_hmp_non_interactive(const Monitor *mon)
-{
-    if (!object_dynamic_cast(OBJECT(mon), TYPE_MONITOR_HMP)) {
-        return false;
-    }
-
-    return !monitor_uses_readline(container_of(mon, MonitorHMP, parent_obj));
-}
-
 static gboolean monitor_unblocked(void *do_not_use, GIOCondition cond,
                                   void *opaque)
 {
@@ -550,12 +531,8 @@ static gboolean qapi_event_throttle_equal(const void *a, const void *b)
     return TRUE;
 }
 
-int monitor_suspend(Monitor *mon)
+void monitor_suspend(Monitor *mon)
 {
-    if (monitor_is_hmp_non_interactive(mon)) {
-        return -ENOTTY;
-    }
-
     qatomic_inc(&mon->suspend_cnt);
 
     if (monitor_requires_iothread(mon)) {
@@ -567,7 +544,6 @@ int monitor_suspend(Monitor *mon)
     }
 
     trace_monitor_suspend(mon, 1);
-    return 0;
 }
 
 static void monitor_accept_input(void *opaque)
@@ -584,10 +560,6 @@ static void monitor_accept_input(void *opaque)
 
 void monitor_resume(Monitor *mon)
 {
-    if (monitor_is_hmp_non_interactive(mon)) {
-        return;
-    }
-
     if (qatomic_dec_fetch(&mon->suspend_cnt) == 0) {
         AioContext *ctx;