On Mon, Aug 10, 2026 at 7:36 PM Alex Bennée <[email protected]> wrote: > > A number of chardev users where calling qemu_chr_fe_get_driver() which > is discouraged as it blocks backend hotswap. As the pattern is common > and need for the string is transitory add a helper and keep > qemu_chr_fe_get_driver() for those that really need the funkiness of > poking around the backend setup. > > Signed-off-by: Alex Bennée <[email protected]> > Suggested-by: Peter Maydell <[email protected]>
Reviewed-by: Marc-André Lureau <[email protected]> > --- > include/chardev/char-fe.h | 13 ++++++++++++- > backends/cryptodev-vhost-user.c | 8 +------- > backends/rng-egd.c | 8 +------- > backends/vhost-user.c | 8 +------- > hw/char/imx_serial.c | 4 ++-- > 5 files changed, 17 insertions(+), 24 deletions(-) > > diff --git a/include/chardev/char-fe.h b/include/chardev/char-fe.h > index 5f8a6df17dc..13218d04c8d 100644 > --- a/include/chardev/char-fe.h > +++ b/include/chardev/char-fe.h > @@ -52,7 +52,8 @@ void qemu_chr_fe_deinit(CharFrontend *c, bool del); > * associated Chardev. > * Note: avoid this function as the driver should never be accessed directly, > * especially by the frontends that support chardevice hotswap. > - * Consider qemu_chr_fe_backend_connected() to check for driver > existence > + * Consider qemu_chr_fe_backend_connected() to check for driver > + * existence or qemu_chr_fe_backend_name() if you need the name. > */ > Chardev *qemu_chr_fe_get_driver(CharFrontend *c); > > @@ -70,6 +71,16 @@ bool qemu_chr_fe_backend_connected(CharFrontend *c); > */ > bool qemu_chr_fe_backend_open(CharFrontend *c); > > +/** > + * qemu_chr_fe_backend_name: > + * > + * Returns: caller freeable string or NULL > + */ > +static inline char * qemu_chr_fe_backend_name(CharFrontend *c) > +{ > + return (c->chr && c->chr->label) ? g_strdup(c->chr->label) : NULL; > +} > + > /** > * qemu_chr_fe_set_handlers_full: > * @c: a CharFrontend > diff --git a/backends/cryptodev-vhost-user.c b/backends/cryptodev-vhost-user.c > index cc478d9902d..3334e280a27 100644 > --- a/backends/cryptodev-vhost-user.c > +++ b/backends/cryptodev-vhost-user.c > @@ -373,13 +373,7 @@ cryptodev_vhost_user_get_chardev(Object *obj, Error > **errp) > { > CryptoDevBackendVhostUser *s = > CRYPTODEV_BACKEND_VHOST_USER(obj); > - Chardev *chr = qemu_chr_fe_get_driver(&s->chr); > - > - if (chr && chr->label) { > - return g_strdup(chr->label); > - } > - > - return NULL; > + return qemu_chr_fe_backend_name(&s->chr); > } > > static void cryptodev_vhost_user_finalize(Object *obj) > diff --git a/backends/rng-egd.c b/backends/rng-egd.c > index 1d92bd71cf7..c2207f40c5c 100644 > --- a/backends/rng-egd.c > +++ b/backends/rng-egd.c > @@ -126,13 +126,7 @@ static void rng_egd_set_chardev(Object *obj, const char > *value, Error **errp) > static char *rng_egd_get_chardev(Object *obj, Error **errp) > { > RngEgd *s = RNG_EGD(obj); > - Chardev *chr = qemu_chr_fe_get_driver(&s->chr); > - > - if (chr && chr->label) { > - return g_strdup(chr->label); > - } > - > - return NULL; > + return qemu_chr_fe_backend_name(&s->chr); > } > > static void rng_egd_finalize(Object *obj) > diff --git a/backends/vhost-user.c b/backends/vhost-user.c > index 380d8250233..46dadb74800 100644 > --- a/backends/vhost-user.c > +++ b/backends/vhost-user.c > @@ -152,13 +152,7 @@ static void set_chardev(Object *obj, const char *value, > Error **errp) > static char *get_chardev(Object *obj, Error **errp) > { > VhostUserBackend *b = VHOST_USER_BACKEND(obj); > - Chardev *chr = qemu_chr_fe_get_driver(&b->chr); > - > - if (chr && chr->label) { > - return g_strdup(chr->label); > - } > - > - return NULL; > + return qemu_chr_fe_backend_name(&b->chr); > } > > static void vhost_user_backend_class_init(ObjectClass *oc, const void *data) > diff --git a/hw/char/imx_serial.c b/hw/char/imx_serial.c > index fb41ee2ac50..8ac4efbb5e9 100644 > --- a/hw/char/imx_serial.c > +++ b/hw/char/imx_serial.c > @@ -278,10 +278,10 @@ static void imx_serial_write(void *opaque, hwaddr > offset, > uint64_t value, unsigned size) > { > IMXSerialState *s = (IMXSerialState *)opaque; > - Chardev *chr = qemu_chr_fe_get_driver(&s->chr); > + g_autofree char *label = qemu_chr_fe_backend_name(&s->chr); > unsigned char ch; > > - trace_imx_serial_write(chr ? chr->label : "NODEV", offset, value); > + trace_imx_serial_write(label ? label : "NODEV", offset, value); > > switch (offset >> 2) { > case 0x10: /* UTXD */ > -- > 2.47.3 > >
