Re: [PATCH v4] eventfd: convert to f_op->read_iter()

[Al Viro]

On Fri, May 01, 2020 at 05:54:09PM -0600, Jens Axboe wrote:
> On 5/1/20 5:12 PM, Al Viro wrote:
> > On Fri, May 01, 2020 at 01:11:09PM -0600, Jens Axboe wrote:
> >> +	flags &= EFD_SHARED_FCNTL_FLAGS;
> >> +	flags |= O_RDWR;
> >> +	fd = get_unused_fd_flags(flags);
> >>  	if (fd < 0)
> >> -		eventfd_free_ctx(ctx);
> >> +		goto err;
> >> +
> >> +	file = anon_inode_getfile("[eventfd]", &eventfd_fops, ctx, flags);
> >> +	if (IS_ERR(file)) {
> >> +		put_unused_fd(fd);
> >> +		fd = PTR_ERR(file);
> >> +		goto err;
> >> +	}
> >>  
> >> +	file->f_mode |= FMODE_NOWAIT;
> >> +	fd_install(fd, file);
> >> +	return fd;
> >> +err:
> >> +	eventfd_free_ctx(ctx);
> >>  	return fd;
> >>  }
> > 
> > Looks sane...  I can take it via vfs.git, or leave it for you if you
> > have other stuff in the same area...
> 
> Would be great if you can queue it up in vfs.git, thanks! Don't have
> anything else that'd conflict with this.

Applied; BTW, what happens if
        ctx->id = ida_simple_get(&eventfd_ida, 0, 0, GFP_KERNEL);
fails?  Quitely succeed with BS value (-ENOSPC/-ENOMEM) shown by
eventfd_show_fdinfo()?