Re: [Qemu-devel] [PATCH 4/6] qemu-char: make writes thread-safe

[Paolo Bonzini]

Il 11/06/2014 08:59, Fam Zheng ha scritto:
> On Tue, 06/03 18:39, Paolo Bonzini wrote:
> > diff --git a/qemu-char.c b/qemu-char.c
> > index b478a3d..dcd0765 100644
> > --- a/qemu-char.c
> > +++ b/qemu-char.c
> > @@ -121,7 +121,12 @@ void qemu_chr_be_generic_open(CharDriverState *s)
> >
> >  int qemu_chr_fe_write(CharDriverState *s, const uint8_t *buf, int len)
> >  {
> > -    return s->chr_write(s, buf, len);
> > +    int ret;
> > +
> > +    qemu_mutex_lock(&s->chr_write_lock);
> > +    ret = s->chr_write(s, buf, len);
> > +    qemu_mutex_unlock(&s->chr_write_lock);
> > +    return ret;
> >  }
> >
> >  int qemu_chr_fe_write_all(CharDriverState *s, const uint8_t *buf, int len)
> > @@ -129,6 +134,7 @@ int qemu_chr_fe_write_all(CharDriverState *s, const uint8_t 
> > *buf, int len)
> >      int offset = 0;
> >      int res;
> >
> > +    qemu_mutex_lock(&s->chr_write_lock);
> >      while (offset < len) {
> >          do {
> >              res = s->chr_write(s, buf + offset, len - offset);
> > @@ -147,6 +153,7 @@ int qemu_chr_fe_write_all(CharDriverState *s, const uint8_t 
> > *buf, int len)
>
> More context in the loop:
>
>               if (res == -1 && errno == EAGAIN) {
>                   g_usleep(100);
>               }
>           } while (res == -1 && errno == EAGAIN);
>
>           if (res == 0) {
>               break;
>           }
>
>           if (res < 0) {
> (*)           return res;
>           }
>
> Doesn't (*) need an unlock?

Indeed, thanks.

Paolo