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Thu, 19 Sep 2019 07:32:59 +0000 (UTC) Received: from [10.36.117.104] (ovpn-117-104.ams2.redhat.com [10.36.117.104]) by smtp.corp.redhat.com (Postfix) with ESMTP id E9490194B2; Thu, 19 Sep 2019 07:32:35 +0000 (UTC) To: Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org References: <20190918130244.24257-1-vsementsov@virtuozzo.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: Date: Thu, 19 Sep 2019 09:32:34 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190918130244.24257-1-vsementsov@virtuozzo.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 19 Sep 2019 07:33:00 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [RFC] error: auto propagated local_err X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fam@euphon.net, peter.maydell@linaro.org, mst@redhat.com, codyprime@gmail.com, mark.cave-ayland@ilande.co.uk, mdroth@linux.vnet.ibm.com, kraxel@redhat.com, mreitz@redhat.com, qemu-block@nongnu.org, quintela@redhat.com, armbru@redhat.com, pasic@linux.ibm.com, borntraeger@de.ibm.com, marcandre.lureau@redhat.com, rth@twiddle.net, farman@linux.ibm.com, groug@kaod.org, dgilbert@redhat.com, alex.williamson@redhat.com, qemu-arm@nongnu.org, stefanha@redhat.com, jsnow@redhat.com, david@gibson.dropbear.id.au, kwolf@redhat.com, berrange@redhat.com, cohuck@redhat.com, qemu-s390x@nongnu.org, sundeep.lkml@gmail.com, qemu-ppc@nongnu.org, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 18.09.19 15:02, Vladimir Sementsov-Ogievskiy wrote: > Hi all! >=20 > Here is a proposal (three of them, actually) of auto propagation for > local_err, to not call error_propagate on every exit point, when we > deal with local_err. >=20 > It also may help make Greg's series[1] about error_append_hint smaller. >=20 > See definitions and examples below. >=20 > I'm cc-ing to this RFC everyone from series[1] CC list, as if we like > it, the idea will touch same code (and may be more). >=20 > [1]: https://lists.gnu.org/archive/html/qemu-devel/2019-09/msg03449.htm= l >=20 > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > include/qapi/error.h | 102 +++++++++++++++++++++++++++++++++++++++++++ > block.c | 63 ++++++++++++-------------- > block/backup.c | 8 +++- > block/gluster.c | 7 +++ > 4 files changed, 144 insertions(+), 36 deletions(-) >=20 > diff --git a/include/qapi/error.h b/include/qapi/error.h > index 3f95141a01..083e061014 100644 > --- a/include/qapi/error.h > +++ b/include/qapi/error.h > @@ -322,6 +322,108 @@ void error_set_internal(Error **errp, > ErrorClass err_class, const char *fmt, ...) > GCC_FMT_ATTR(6, 7); > =20 > +typedef struct ErrorPropagator { > + Error **errp; > + Error *local_err; > +} ErrorPropagator; > + > +static inline void error_propagator_cleanup(ErrorPropagator *prop) > +{ > + if (prop->local_err) { > + error_propagate(prop->errp, prop->local_err); > + } > +} > + > +G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(ErrorPropagator, error_propagator_cle= anup); > + > +/* > + * ErrorPropagationPair > + * > + * [Error *local_err, Error **errp] > + * > + * First element is local_err, second is original errp, which is propa= gation > + * target. Yes, errp has a bit another type, so it should be converted= . > + * > + * ErrorPropagationPair may be used as errp, which points to local_err= , > + * as it's type is compatible. > + */ > +typedef Error *ErrorPropagationPair[2]; > + > +static inline void error_propagation_pair_cleanup(ErrorPropagationPair= *arr) > +{ > + Error *local_err =3D (*arr)[0]; > + Error **errp =3D (Error **)(*arr)[1]; > + > + if (local_err) { > + error_propagate(errp, local_err); > + } > +} > + > +G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(ErrorPropagationPair, > + error_propagation_pair_cleanup); > + > +/* > + * DEF_AUTO_ERRP > + * > + * Define auto_errp variable, which may be used instead of errp, and > + * *auto_errp may be safely checked to be zero or not, and may be safe= ly > + * used for error_append_hint(). auto_errp is automatically propagated > + * to errp at function exit. > + */ > +#define DEF_AUTO_ERRP(auto_errp, errp) \ > + g_auto(ErrorPropagationPair) (auto_errp) =3D {NULL, (Error *)(errp= )} > + > + > +/* > + * Another variant: > + * Pros: > + * - normal structure instead of cheating with array > + * - we can directly use errp, if it's not NULL and don't point to > + * error_abort or error_fatal > + * Cons: > + * - we need to define two variables instead of one > + */ > +typedef struct ErrorPropagationStruct { > + Error *local_err; > + Error **errp; > +} ErrorPropagationStruct; > + > +static inline void error_propagation_struct_cleanup(ErrorPropagationSt= ruct *prop) > +{ > + if (prop->local_err) { > + error_propagate(prop->errp, prop->local_err); > + } > +} > + > +G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(ErrorPropagationStruct, > + error_propagation_struct_cleanup); > + > +#define DEF_AUTO_ERRP_V2(auto_errp, errp) \ > + g_auto(ErrorPropagationStruct) (__auto_errp_prop) =3D {.errp =3D (= errp)}; \ > + Error **auto_errp =3D \ > + ((errp) =3D=3D NULL || *(errp) =3D=3D error_abort || *(errp) =3D= =3D error_fatal) ? \ > + &__auto_errp_prop.local_err : \ > + (errp); > + > +/* > + * Third variant: > + * Pros: > + * - simpler movement for functions which don't have local_err yet > + * the only thing to do is to call one macro at function start. > + * This extremely simplifies Greg's series > + * Cons: > + * - looks like errp shadowing.. Still seems safe. > + * - must be after all definitions of local variables and before a= ny > + * code. > + * - like v2, several statements in one open macro > + */ > +#define MAKE_ERRP_SAFE(errp) \ > +g_auto(ErrorPropagationStruct) (__auto_errp_prop) =3D {.errp =3D (errp= )}; \ > +if ((errp) =3D=3D NULL || *(errp) =3D=3D error_abort || *(errp) =3D=3D= error_fatal) { \ > + (errp) =3D &__auto_errp_prop.local_err; \ > +} Using that idea, what about something like this: diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c index 8bfb6684cb..043ad69f8b 100644 --- a/hw/s390x/s390-virtio-ccw.c +++ b/hw/s390x/s390-virtio-ccw.c @@ -58,22 +58,42 @@ S390CPU *s390_cpu_addr2state(uint16_t cpu_addr) return S390_CPU(ms->possible_cpus->cpus[cpu_addr].cpu); } =20 +typedef struct ErrorPropagator { + Error **errp; + Error *local_err; +} ErrorPropagator; + +static inline void error_propagator_cleanup(ErrorPropagator *prop) +{ + if (prop->local_err) { + error_propagate(prop->errp, prop->local_err); + } +} + +G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(ErrorPropagator, error_propagator_clean= up); + +#define DEFINE_LOCAL_ERRP(_errp) \ +g_auto(ErrorPropagator) (__auto_errp_prop) =3D {.errp =3D (_errp)}; \ +Error **local_errp =3D &__auto_errp_prop.local_err + static S390CPU *s390x_new_cpu(const char *typename, uint32_t core_id, Error **errp) { + DEFINE_LOCAL_ERRP(errp); S390CPU *cpu =3D S390_CPU(object_new(typename)); - Error *err =3D NULL; =20 - object_property_set_int(OBJECT(cpu), core_id, "core-id", &err); - if (err !=3D NULL) { + object_property_set_int(OBJECT(cpu), core_id, "core-id", local_errp)= ; + if (*local_errp !=3D NULL) { goto out; } - object_property_set_bool(OBJECT(cpu), true, "realized", &err); + object_property_set_bool(OBJECT(cpu), true, "realized", local_errp); =20 out: object_unref(OBJECT(cpu)); - if (err) { - error_propagate(errp, err); + if (*local_errp) { cpu =3D NULL; } return cpu; --=20 Thanks, David / dhildenb