chardev/char-fe: Allow NULL chardev in qemu_chr_fe_init()

All the functions in char-fe.c handle the CharBackend
having a NULL Chardev pointer, which means that the
backend exists but is not connected to anything. The
exception is qemu_chr_fe_init(), which will crash if
passed a NULL Chardev pointer argument. This can happen
for various boards if they're started with 'nodefaults':
 arm-softmmu/qemu-system-arm -S -nodefaults -M cubieboard
 riscv32-softmmu/qemu-system-riscv32 -nodefaults -M sifive_e

Make qemu_chr_fe_init() accept a NULL chardev. This allows
UART models to handle NULL chardev properties without
generally needing to special case them or to manually
create a NullChardev.

Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20180323152948.27048-1-peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Peter Maydell 2018-03-23 15:29:48 +00:00 committed by Paolo Bonzini
parent 90c558beca
commit 12051d82f0

View File

@ -198,6 +198,7 @@ bool qemu_chr_fe_init(CharBackend *b, Chardev *s, Error **errp)
{ {
int tag = 0; int tag = 0;
if (s) {
if (CHARDEV_IS_MUX(s)) { if (CHARDEV_IS_MUX(s)) {
MuxChardev *d = MUX_CHARDEV(s); MuxChardev *d = MUX_CHARDEV(s);
@ -212,6 +213,7 @@ bool qemu_chr_fe_init(CharBackend *b, Chardev *s, Error **errp)
} else { } else {
s->be = b; s->be = b;
} }
}
b->fe_open = false; b->fe_open = false;
b->tag = tag; b->tag = tag;