Re: [Qemu-devel] [PATCH] aio-posix: fill error message that is missed

[Cao jin]

On 07/13/2016 09:33 AM, Fam Zheng wrote:
> On Tue, 07/12 09:41, Eric Blake wrote:
> > On 07/12/2016 05:34 AM, Cao jin wrote:
> > > The current judegement of caller is meaningless, make it useful.
> >
> > Is this something you can trigger? If so, what command line?  If not,
> > how did you find it?
> >
> > Spelled 'judgment', not 'judegement'; but rather than just fixing the
> > typo, it might read better as:
> >
> > The lone caller of aio_context_setup() only checks whether an error was
> > set, but aio_context_setup() is not setting an error.
> >
> > > Signed-off-by: Cao jin <address@hidden>
> > > ---
> > >   aio-posix.c | 2 ++
> > >   1 file changed, 2 insertions(+)
> > >
> > > diff --git a/aio-posix.c b/aio-posix.c
> > > index 6006122..8b0deb7 100644
> > > --- a/aio-posix.c
> > > +++ b/aio-posix.c
> > > @@ -18,6 +18,7 @@
> > >   #include "block/block.h"
> > >   #include "qemu/queue.h"
> > >   #include "qemu/sockets.h"
> > > +#include "qapi/error.h"
> > >   #ifdef CONFIG_EPOLL_CREATE1
> > >   #include <sys/epoll.h>
> > >   #endif
> > > @@ -491,6 +492,7 @@ void aio_context_setup(AioContext *ctx, Error **errp)
> > >       assert(!ctx->epollfd);
> > >       ctx->epollfd = epoll_create1(EPOLL_CLOEXEC);
> > >       if (ctx->epollfd == -1) {
> > > +        error_setg_errno(errp, errno, "Failed to create epoll instance");
> > >           ctx->epoll_available = false;
> > >       } else {
> > >           ctx->epoll_available = true;
> >
> > However, I'm not even sure your patch is right.  The mere fact that we
> > have ctx->epoll_available makes it sound like we WANT to be able to
> > gracefully fall back when epoll is not available, rather than raising an
> > error message.
>
> Yes. This patch doesn't make sense to me. What can be done is 1) remove errp
> parameter as it's not used; 2) fprintf(stderr, ...) or error_report(....) here
> if epoll_create1 failed.
>
> Fam

Actually, my first thought is 1), and I also checked how 
ctx->epoll_available is used(seems I still didn't read it carefully). 
But when I see how event_notifier_init()'s failure(in aio_context_new()) 
is handled, I think maybe keeping consistence is better.

ok, I will choose 1)

--
Yours Sincerely,

Cao jin