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Date: Mon, 13 Feb 2012 09:17:08 +0000
From: "Daniel P. Berrange" <berrange@redhat.com>
Message-ID: <20120213091708.GA32182@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] oslib: make error handling more reasonable
Reply-To: "Daniel P. Berrange" <berrange@redhat.com>
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To: Eric Blake <eblake@redhat.com>
Cc: Zhi Yong Wu <zwu.kernel@gmail.com>, Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>, qemu-devel@nongnu.org, stefanha@linux.vnet.ibm.com

On Fri, Feb 10, 2012 at 11:35:11AM -0700, Eric Blake wrote:
> On 02/10/2012 07:41 AM, Daniel P. Berrange wrote:
> 
> >> @@ -80,7 +80,7 @@ void *qemu_oom_check(void *ptr)
> >>  {
> >>      if (ptr == NULL) {
> >>          fprintf(stderr, "Failed to allocate memory: %s\n", strerror(errno));
> >> -        abort();
> >> +        exit(EXIT_FAILURE);
> > 
> > exit() will call any atexit()/on_exit() handlers, as well as trying
> > to flush I/O streams. Any of these actions may require further
> > memory allocations, which will likely fail, or worse cause this
> > code to re-enter itself if an atexit() handler calls qemu_malloc
> > 
> > The only option other than abort(), is to use  _Exit() which
> > doesn't try to run cleanup handlers.
> 
> Correct, but in that case, then you need to fflush(stderr) prior to
> _Exit(), or else use write() rather than fprintf(), since otherwise your
> attempt at a nice oom error message is lost.

IIRC, stderr is not buffered, so should not need to be flushed.

Daniel
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