From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56286) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XNLj7-000253-41 for qemu-devel@nongnu.org; Fri, 29 Aug 2014 08:56:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XNLj2-0002OF-9u for qemu-devel@nongnu.org; Fri, 29 Aug 2014 08:56:25 -0400 Date: Fri, 29 Aug 2014 08:55:21 -0400 From: Luiz Capitulino Message-ID: <20140829085521.788ce268@redhat.com> In-Reply-To: <5400347A.9040105@huawei.com> References: <1409138333-12644-1-git-send-email-zhang.zhanghailiang@huawei.com> <20140827091827.4de1dc59@redhat.com> <5400347A.9040105@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] dump: let dump_error printf the error reason List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: zhanghailiang Cc: qemu-trivial@nongnu.org, luonengjun@huawei.com, lersek@redhat.com, qemu-devel@nongnu.org, peter.huangpeng@huawei.com On Fri, 29 Aug 2014 16:06:18 +0800 zhanghailiang wrote: > On 2014/8/27 21:18, Luiz Capitulino wrote: > > On Wed, 27 Aug 2014 19:18:53 +0800 > > zhanghailiang wrote: > > > >> The second parameter of dump_error is unused, but one purpose of > >> using this function is to report the error info. > >> > >> Signed-off-by: zhanghailiang > >> --- > >> dump.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/dump.c b/dump.c > >> index 71d3e94..0f44e9d 100644 > >> --- a/dump.c > >> +++ b/dump.c > >> @@ -83,6 +83,9 @@ static int dump_cleanup(DumpState *s) > >> > >> static void dump_error(DumpState *s, const char *reason) > >> { > >> + if (reason) { > >> + error_report("%s", reason); > >> + } > >> dump_cleanup(s); > >> } > >> > > > > Good catch, but error_report() will report the error only to the user. This > > is QMP code, so we have to use the Error API. > > > > I think that the best way to solve this is to make dump_error() fill an > > Error object (eg. by calling error_setg()) and then returning it after > > the call to dump_cleanup(). Of course that you will have to change _all_ > > code paths calling dump_error() to propagate the error up. > > > > For more information on this, please read docs/writing-qmp-commands.txt. > > You can also take a look at simple commands doing error propagation, like > > qmp_cont() or qmp_block_passwd(). > > > > . > > > Hi, > > Thanks for your review. > > Actually, for all paths that call dump_error, at last they will come into a > common path which will call error_setg(). > > The call process as below: > qmp_dump_guest_memory > (1) -->create_kdump_vmcore > -->write_start_flat_header > -->dump_error > -->write_end_flat_header > -->dump_error > ... > -->error_set(errp, QERR_IO_ERROR)(if create_kdump_vmcore failed) > (2) -->create_vmcore > -->dump_begin > -->write_elf64_header > -->dump_error > -->write_elf64_note > -->dump_error > ... > -->dump_iterate > -->write_data > -->dump_error > ... > -->error_set(errp, QERR_IO_ERROR)(if create_kdump_vmcore failed) > > And a short *IO ERROR* info will be returned to the caller of qmp_dump_guest_memory. > > So, is it OK in dump_error just report the detailed error info to users > (actually, it will be stored in qemu log)? Or should these error info > also returned to the caller? The errors should be propagated up to the caller. This way they can be consumed by QMP and HMP. > > What's your suggestion? Thanks.:) > > Best Regards, > zhanghailiang > > > >