Re: [Qemu-devel] [PATCH v3] async: aio_context_new(): Handle event_notifier_init failure

["Benoît Canet" <benoit.canet@irqsave.net>]

The Tuesday 16 Sep 2014 à 13:40:24 (-0600), Eric Blake wrote :
> On 09/16/2014 12:04 PM, Chrysostomos Nanakos wrote:
> > If event_notifier_init fails QEMU exits without printing
> > any error information to the user. This commit adds an error
> > message on failure:
> > 
> >  # qemu [...]
> 
> Showing the actual command line you used would be helpful.
> 
> >  qemu: Failed to initialize event notifier: Too many open files in system
> > 
> > Signed-off-by: Chrysostomos Nanakos <cnanakos@grnet.gr>
> > ---
> >  async.c                  |   16 +++++++++++-----
> >  include/block/aio.h      |    2 +-
> >  include/qemu/main-loop.h |    2 +-
> >  iothread.c               |   11 ++++++++++-
> >  main-loop.c              |    9 +++++++--
> >  qemu-img.c               |    8 +++++++-
> >  qemu-io.c                |    7 ++++++-
> >  qemu-nbd.c               |    6 +++++-
> >  tests/test-aio.c         |   10 +++++++++-
> >  tests/test-thread-pool.c |   10 +++++++++-
> >  tests/test-throttle.c    |   10 +++++++++-
> >  vl.c                     |    5 +++--
> >  12 files changed, 78 insertions(+), 18 deletions(-)
> > 
> 
> > -AioContext *aio_context_new(void)
> > +AioContext *aio_context_new(Error **errp)
> >  {
> > +    int ret;
> >      AioContext *ctx;
> >      ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext));
> > +    ret = event_notifier_init(&ctx->notifier, false);
> > +    if (ret < 0) {
> > +        g_source_destroy(&ctx->source);
> 
> Does g_source_destroy() guarantee that errno is unmolested? If not,
> 
> > +        error_setg_errno(errp, -ret, "Failed to initialize event notifier");

Actually -ret is passed to error_setg_errno.

See.

void error_set_errno(Error **errp, int os_errno, ErrorClass err_class,          
                     const char *fmt, ...) 
and
    if (os_errno != 0) {                                                        
            err->msg = g_strdup_printf("%s: %s", msg1, strerror(os_errno));  

> Use of \' inside "" is unusual. (Multiple times in your patch)

My fault.