From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH V3] xl: create VFB for PV guest when VNC is specified Date: Tue, 17 Dec 2013 11:36:29 +0000 Message-ID: <52B0373D.1080602@citrix.com> References: <1387215576-17455-1-git-send-email-wei.liu2@citrix.com> <1387215964.21086.54.camel@kazak.uk.xensource.com> <20131217112809.GC26994@zion.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20131217112809.GC26994@zion.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Wei Liu Cc: Ian Jackson , Ian Campbell , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 17/12/13 11:28, Wei Liu wrote: > On Mon, Dec 16, 2013 at 05:46:04PM +0000, Ian Campbell wrote: > [...] >>> Changes in V2: >>> * use macros to reduce code duplication >>> * vfb=[] take precedence over top level VNC options >>> --- >>> tools/libxl/xl_cmdimpl.c | 89 ++++++++++++++++++++++++++++++++++++---------- >>> 1 file changed, 70 insertions(+), 19 deletions(-) >>> >>> diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c >>> index bd26bcc..6a22e17 100644 >>> --- a/tools/libxl/xl_cmdimpl.c >>> +++ b/tools/libxl/xl_cmdimpl.c >>> @@ -315,6 +315,13 @@ static void *xrealloc(void *ptr, size_t sz) { >>> return r; >>> } >>> >>> +#define ARRAY_EXTEND(array,count) \ >>> + do { \ >>> + (array) = xrealloc((array), \ >>> + sizeof(typeof(*(array))) * ((count) + 1)); \ >> sizeof(typeof(*array)) == sizeof(*array), doesn't it? >> >>> + (count) = (count) + 1; \ >> (count++) >> >> I suppose in a macro like this it is tricky to arrange to only evaluate >> the arguments once, since you need to read and write, but I think you >> can arrange to evaluate array exactly once instead of 3 times and count >> just once. >> > I came up with this. Is it what you asked for? > > #define ARRAY_EXTEND(type_ptr,ptr,type_count,count,ret) \ > do { \ > type_ptr **__ptr = &(ptr); \ > type_count *__count = &(count); \ > *__ptr = xrealloc(*__ptr, \ > sizeof(**__ptr) * (*__count + 1)); \ > (ret) = *__ptr + *__count; \ > (*__count)++; \ > } while (0) > > Wei. Use typeof() rather than passing the types in directly. It is a GCC extension, which tries its best not to evaluate its argument. Alternatively, the __auto_type gcc keyword sould seem to do what you want as well. ~Andrew