[Qemu-devel] [PATCH v2 3/6] char: add a QEMU_CHAR_FEATURE_GCONTEXT flag

["Marc-André Lureau" <marcandre.lureau@redhat.com>]

The feature should be set if the chardev is able to switch
GMainContext. Callers that want to put a chardev in a different thread
context can/should check this capabilities.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 include/chardev/char.h |  3 +++
 chardev/char.c         | 11 +++++++++++
 2 files changed, 14 insertions(+)

diff --git a/include/chardev/char.h b/include/chardev/char.h
index 7becd8c80c..014566c3de 100644
--- a/include/chardev/char.h
+++ b/include/chardev/char.h
@@ -47,6 +47,9 @@ typedef enum {
     QEMU_CHAR_FEATURE_FD_PASS,
     /* Whether replay or record mode is enabled */
     QEMU_CHAR_FEATURE_REPLAY,
+    /* Whether the gcontext can be changed after calling
+     * qemu_chr_be_update_read_handlers() */
+    QEMU_CHAR_FEATURE_GCONTEXT,
 
     QEMU_CHAR_FEATURE_LAST,
 } ChardevFeature;
diff --git a/chardev/char.c b/chardev/char.c
index 7f07a1bfbd..b5ee58b7d2 100644
--- a/chardev/char.c
+++ b/chardev/char.c
@@ -196,6 +196,8 @@ void qemu_chr_be_update_read_handlers(Chardev *s,
     s->gcontext = context;
     if (cc->chr_update_read_handler) {
         cc->chr_update_read_handler(s);
+    } else if (s->gcontext) {
+        error_report("switching context isn't supported by this chardev");
     }
 }
 
@@ -240,6 +242,15 @@ static void char_init(Object *obj)
 
     chr->logfd = -1;
     qemu_mutex_init(&chr->chr_write_lock);
+
+    /*
+     * Assume if chr_update_read_handler is implemented it will
+     * take the updated gcontext into account.
+     */
+    if (CHARDEV_GET_CLASS(chr)->chr_update_read_handler) {
+        qemu_chr_set_feature(chr, QEMU_CHAR_FEATURE_GCONTEXT);
+    }
+
 }
 
 static int null_chr_write(Chardev *chr, const uint8_t *buf, int len)
-- 
2.19.0.271.gfe8321ec05