Re: [Qemu-devel] [PATCH] migrate.c: migrate_fd_put_buffer: Do not busyloop: stop writing if EWOULDBLOCK

[Anthony Liguori]

Dor Laor wrote:
> Uri Lublin wrote:
> > The migration code is non-blocking, designed for live migration.
> >
> > Practically migrate_fd_put_buffer busy-loops trying to write, as
> > on many machines EWOULDBLOCK==EAGAIN (look in 
> > include/asm-generic/errno.h).
> >
> > Signed-off-by: Uri Lublin <address@hidden>
> > ---
> >  migration.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/migration.c b/migration.c
> > index 859d945..ca397fa 100644
> > --- a/migration.c
> > +++ b/migration.c
> > @@ -176,7 +176,7 @@ ssize_t migrate_fd_put_buffer(void *opaque, const 
> > void *data, size_t size)
> >  
> >      do {
> >          ret = s->write(s, data, size);
> > -    } while (ret == -1 && ((s->get_error(s)) == EINTR || 
> > (s->get_error(s)) == EWOULDBLOCK));
> > +    } while (ret == -1 && ((s->get_error(s)) == EINTR));
> >  
> >      if (ret == -1)
> >          ret = -(s->get_error(s));
> >   
> There is additional stuff that needs to test EWOULDBLOCK in further 
> locations in the code.
> Otherwise migration will fail.
>
> commit 2d875410cb168fa728dcde96885a3e4ddfd0bb58
> Author: Dor Laor <address@hidden>
> Date:   Thu May 21 12:29:39 2009 +0300
>
>    The migration code is non-blocking, designed for live migration.
>      Practically migrate_fd_put_buffer busy-loops trying to write, as
>    on many machines EWOULDBLOCK==EAGAIN (look in 
> include/asm-generic/errno.h).
>      Based on Uri Lublin's patch.
>    Signed-off-by: Dor Laor <address@hidden>

This is whitespace damaged, presumably from copy/paste, can you resend?

--
Regards,

Anthony Liguori