From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:37611) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RwpPo-0000mD-B5 for qemu-devel@nongnu.org; Mon, 13 Feb 2012 01:29:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RwpPm-0003pk-Mb for qemu-devel@nongnu.org; Mon, 13 Feb 2012 01:29:32 -0500 Received: from v220110690675601.yourvserver.net ([78.47.199.172]:38599) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RwpPm-0003pA-F4 for qemu-devel@nongnu.org; Mon, 13 Feb 2012 01:29:30 -0500 Message-ID: <4F38ADC7.8080108@weilnetz.de> Date: Mon, 13 Feb 2012 07:29:27 +0100 From: Stefan Weil MIME-Version: 1.0 References: <1328884453-1067-1-git-send-email-zwu.kernel@gmail.com> <20120210144115.GI2914@redhat.com> <4F353D75.2050801@weilnetz.de> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] oslib: make error handling more reasonable List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Zhi Yong Wu Cc: Stefan Hajnoczi , QEMU Developers Am 13.02.2012 03:37, schrieb Zhi Yong Wu: > On Fri, Feb 10, 2012 at 11:53 PM, Stefan Weil wrote: >> Am 10.02.2012 16:13, schrieb Zhi Yong Wu: >> >>> On Fri, Feb 10, 2012 at 10:41 PM, Daniel P. Berrange >>> wrote: >>>> >>>> On Fri, Feb 10, 2012 at 10:34:13PM +0800, Zhi Yong Wu wrote: >>>>> >>>>> From: Zhi Yong Wu >>>>> >>>>> Signed-off-by: Zhi Yong Wu >>>>> --- >>>>> oslib-posix.c | 4 ++-- >>>>> oslib-win32.c | 4 ++-- >>>>> 2 files changed, 4 insertions(+), 4 deletions(-) >>>>> >>>>> diff --git a/oslib-posix.c b/oslib-posix.c >>>>> index b6a3c7f..f978d56 100644 >>>>> --- a/oslib-posix.c >>>>> +++ b/oslib-posix.c >>>>> @@ -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 >>> >>> Nice, very reasonable. >>>> >>>> >>>> The only option other than abort(), is to use _Exit() which >>>> doesn't try to run cleanup handlers. >>> >>> I will try to send out v2 >> >> >> Could you please explain why calling exit, _Exit or _exit is more >> reasonable than calling abort? >> >> abort can create core dumps or start a debugger which is >> useful for me and maybe other developers, too. > pls refer to > http://lists.gnu.org/archive/html/qemu-devel/2012-02/msg01270.html. > In the scenario, the user should not see core dump, and he perhaps > think that one bug exists in qemu code. > So we hope to use _Exit() instead of abort() here. So you say that you don't want a core dump just because the user called QEMU with -m 4000 or some other large value. Allocating RAM for the emulated machine is perhaps the only scenario where a core dump is indeed not reasonable. In most other cases, out-of-memory is an indication of a QEMU internal problem, so a core dump should be written. I therefore suggest to restrict any modification to the handling of -m. In that case you could even improve the error message by telling the user how much memory would be possible. Simply call the allocating function with decreasing values until it no longer fails. Regards, Stefan Weil