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GET /api/patches/985214/?format=api
HTTP 200 OK
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{
    "id": 985214,
    "url": "http://patchwork.ozlabs.org/api/patches/985214/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20181017082702.5581-2-armbru@redhat.com/",
    "project": {
        "id": 14,
        "url": "http://patchwork.ozlabs.org/api/projects/14/?format=api",
        "name": "QEMU Development",
        "link_name": "qemu-devel",
        "list_id": "qemu-devel.nongnu.org",
        "list_email": "qemu-devel@nongnu.org",
        "web_url": "",
        "scm_url": "",
        "webscm_url": "",
        "list_archive_url": "",
        "list_archive_url_format": "",
        "commit_url_format": ""
    },
    "msgid": "<20181017082702.5581-2-armbru@redhat.com>",
    "list_archive_url": null,
    "date": "2018-10-17T08:26:25",
    "name": "[v4,01/38] error: Fix use of error_prepend() with &error_fatal, &error_abort",
    "commit_ref": null,
    "pull_url": null,
    "state": "new",
    "archived": false,
    "hash": "69c3afdc3e8df2c3982a41b639d0f8fa7eebc2e2",
    "submitter": {
        "id": 2645,
        "url": "http://patchwork.ozlabs.org/api/people/2645/?format=api",
        "name": "Markus Armbruster",
        "email": "armbru@redhat.com"
    },
    "delegate": null,
    "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20181017082702.5581-2-armbru@redhat.com/mbox/",
    "series": [
        {
            "id": 71196,
            "url": "http://patchwork.ozlabs.org/api/series/71196/?format=api",
            "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=71196",
            "date": "2018-10-17T08:26:36",
            "name": "Replace some unwise uses of error_report() & friends",
            "version": 4,
            "mbox": "http://patchwork.ozlabs.org/series/71196/mbox/"
        }
    ],
    "comments": "http://patchwork.ozlabs.org/api/patches/985214/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/985214/checks/",
    "tags": {},
    "related": [],
    "headers": {
        "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>",
        "X-Original-To": "incoming@patchwork.ozlabs.org",
        "Delivered-To": "patchwork-incoming@bilbo.ozlabs.org",
        "Authentication-Results": [
            "ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; helo=lists.gnu.org;\n\tenvelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n\treceiver=<UNKNOWN>)",
            "ozlabs.org;\n\tdmarc=fail (p=none dis=none) header.from=redhat.com"
        ],
        "Received": [
            "from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11])\n\t(using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 42ZlkD6mcVz9s9J\n\tfor <incoming@patchwork.ozlabs.org>;\n\tWed, 17 Oct 2018 19:30:44 +1100 (AEDT)",
            "from localhost ([::1]:34511 helo=lists.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.71) (envelope-from\n\t<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>)\n\tid 1gChE1-0002VH-NW\n\tfor incoming@patchwork.ozlabs.org; Wed, 17 Oct 2018 04:30:41 -0400",
            "from eggs.gnu.org ([2001:4830:134:3::10]:51030)\n\tby lists.gnu.org with esmtp (Exim 4.71)\n\t(envelope-from <armbru@redhat.com>) id 1gChAb-000855-Ip\n\tfor qemu-devel@nongnu.org; Wed, 17 Oct 2018 04:27:11 -0400",
            "from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)\n\t(envelope-from <armbru@redhat.com>) id 1gChAY-0000za-61\n\tfor qemu-devel@nongnu.org; Wed, 17 Oct 2018 04:27:09 -0400",
            "from mx1.redhat.com ([209.132.183.28]:53280)\n\tby eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)\n\t(Exim 4.71) (envelope-from <armbru@redhat.com>) id 1gChAX-0000wr-Qt\n\tfor qemu-devel@nongnu.org; Wed, 17 Oct 2018 04:27:06 -0400",
            "from smtp.corp.redhat.com\n\t(int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15])\n\t(using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby mx1.redhat.com (Postfix) with ESMTPS id F0FF525C20;\n\tWed, 17 Oct 2018 08:27:03 +0000 (UTC)",
            "from blackfin.pond.sub.org (ovpn-116-50.ams2.redhat.com\n\t[10.36.116.50])\n\tby smtp.corp.redhat.com (Postfix) with ESMTPS id 8689C18763;\n\tWed, 17 Oct 2018 08:27:03 +0000 (UTC)",
            "by blackfin.pond.sub.org (Postfix, from userid 1000)\n\tid 196481132F35; Wed, 17 Oct 2018 10:27:02 +0200 (CEST)"
        ],
        "From": "Markus Armbruster <armbru@redhat.com>",
        "To": "qemu-devel@nongnu.org",
        "Date": "Wed, 17 Oct 2018 10:26:25 +0200",
        "Message-Id": "<20181017082702.5581-2-armbru@redhat.com>",
        "In-Reply-To": "<20181017082702.5581-1-armbru@redhat.com>",
        "References": "<20181017082702.5581-1-armbru@redhat.com>",
        "MIME-Version": "1.0",
        "Content-Type": "text/plain; charset=UTF-8",
        "X-Scanned-By": "MIMEDefang 2.79 on 10.5.11.15",
        "X-Greylist": "Sender IP whitelisted, not delayed by milter-greylist-4.5.16\n\t(mx1.redhat.com [10.5.110.30]);\n\tWed, 17 Oct 2018 08:27:04 +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": "[Qemu-devel] [PATCH v4 01/38] error: Fix use of error_prepend()\n\twith &error_fatal, &error_abort",
        "X-BeenThere": "qemu-devel@nongnu.org",
        "X-Mailman-Version": "2.1.21",
        "Precedence": "list",
        "List-Id": "<qemu-devel.nongnu.org>",
        "List-Unsubscribe": "<https://lists.nongnu.org/mailman/options/qemu-devel>,\n\t<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>",
        "List-Archive": "<http://lists.nongnu.org/archive/html/qemu-devel/>",
        "List-Post": "<mailto:qemu-devel@nongnu.org>",
        "List-Help": "<mailto:qemu-devel-request@nongnu.org?subject=help>",
        "List-Subscribe": "<https://lists.nongnu.org/mailman/listinfo/qemu-devel>,\n\t<mailto:qemu-devel-request@nongnu.org?subject=subscribe>",
        "Cc": "Fei Li <fli@suse.com>",
        "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org",
        "Sender": "\"Qemu-devel\"\n\t<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>"
    },
    "content": "From include/qapi/error.h:\n\n  * Pass an existing error to the caller with the message modified:\n  *     error_propagate(errp, err);\n  *     error_prepend(errp, \"Could not frobnicate '%s': \", name);\n\nFei Li pointed out that doing error_propagate() first doesn't work\nwell when @errp is &error_fatal or &error_abort: the error_prepend()\nis never reached.\n\nSince I doubt fixing the documentation will stop people from getting\nit wrong, introduce error_propagate_prepend(), in the hope that it\nlures people away from using its constituents in the wrong order.\nUpdate the instructions in error.h accordingly.\n\nConvert existing error_prepend() next to error_propagate to\nerror_propagate_prepend().  If any of these get reached with\n&error_fatal or &error_abort, the error messages improve.  I didn't\ncheck whether that's the case anywhere.\n\nCc: Fei Li <fli@suse.com>\nSigned-off-by: Markus Armbruster <armbru@redhat.com>\nReviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>\nReviewed-by: Eric Blake <eblake@redhat.com>\n---\n block.c                 |  6 +++---\n block/qcow2.c           |  4 ++--\n block/qed.c             |  4 ++--\n hw/9pfs/9p-local.c      |  4 ++--\n hw/intc/xics.c          | 15 +++++++++------\n hw/ppc/pnv_core.c       |  4 ++--\n hw/ppc/spapr_pci.c      |  7 +++----\n hw/timer/aspeed_timer.c |  3 +--\n hw/usb/bus.c            |  5 +++--\n hw/vfio/pci.c           |  3 +--\n include/qapi/error.h    | 14 ++++++++++++++\n migration/migration.c   | 12 ++++++------\n util/error.c            | 13 +++++++++++++\n 13 files changed, 61 insertions(+), 33 deletions(-)",
    "diff": "diff --git a/block.c b/block.c\nindex 7710b399a3..5d51419d21 100644\n--- a/block.c\n+++ b/block.c\n@@ -4697,9 +4697,9 @@ bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp)\n     assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);\n     if (!QLIST_EMPTY(&bs->op_blockers[op])) {\n         blocker = QLIST_FIRST(&bs->op_blockers[op]);\n-        error_propagate(errp, error_copy(blocker->reason));\n-        error_prepend(errp, \"Node '%s' is busy: \",\n-                      bdrv_get_device_or_node_name(bs));\n+        error_propagate_prepend(errp, error_copy(blocker->reason),\n+                                \"Node '%s' is busy: \",\n+                                bdrv_get_device_or_node_name(bs));\n         return true;\n     }\n     return false;\ndiff --git a/block/qcow2.c b/block/qcow2.c\nindex 7277feda13..4f8d2fa7bd 100644\n--- a/block/qcow2.c\n+++ b/block/qcow2.c\n@@ -2208,8 +2208,8 @@ static void coroutine_fn qcow2_co_invalidate_cache(BlockDriverState *bs,\n     qemu_co_mutex_unlock(&s->lock);\n     qobject_unref(options);\n     if (local_err) {\n-        error_propagate(errp, local_err);\n-        error_prepend(errp, \"Could not reopen qcow2 layer: \");\n+        error_propagate_prepend(errp, local_err,\n+                                \"Could not reopen qcow2 layer: \");\n         bs->drv = NULL;\n         return;\n     } else if (ret < 0) {\ndiff --git a/block/qed.c b/block/qed.c\nindex 689ea9d4d5..9377c0b7ad 100644\n--- a/block/qed.c\n+++ b/block/qed.c\n@@ -1606,8 +1606,8 @@ static void coroutine_fn bdrv_qed_co_invalidate_cache(BlockDriverState *bs,\n     ret = bdrv_qed_do_open(bs, NULL, bs->open_flags, &local_err);\n     qemu_co_mutex_unlock(&s->table_lock);\n     if (local_err) {\n-        error_propagate(errp, local_err);\n-        error_prepend(errp, \"Could not reopen qed layer: \");\n+        error_propagate_prepend(errp, local_err,\n+                                \"Could not reopen qed layer: \");\n         return;\n     } else if (ret < 0) {\n         error_setg_errno(errp, -ret, \"Could not reopen qed layer\");\ndiff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c\nindex c30f4f26bd..08e673a79c 100644\n--- a/hw/9pfs/9p-local.c\n+++ b/hw/9pfs/9p-local.c\n@@ -1509,8 +1509,8 @@ static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse, Error **errp)\n \n     fsdev_throttle_parse_opts(opts, &fse->fst, &local_err);\n     if (local_err) {\n-        error_propagate(errp, local_err);\n-        error_prepend(errp, \"invalid throttle configuration: \");\n+        error_propagate_prepend(errp, local_err,\n+                                \"invalid throttle configuration: \");\n         return -1;\n     }\n \ndiff --git a/hw/intc/xics.c b/hw/intc/xics.c\nindex c90c893228..406efee064 100644\n--- a/hw/intc/xics.c\n+++ b/hw/intc/xics.c\n@@ -320,8 +320,9 @@ static void icp_realize(DeviceState *dev, Error **errp)\n \n     obj = object_property_get_link(OBJECT(dev), ICP_PROP_XICS, &err);\n     if (!obj) {\n-        error_propagate(errp, err);\n-        error_prepend(errp, \"required link '\" ICP_PROP_XICS \"' not found: \");\n+        error_propagate_prepend(errp, err,\n+                                \"required link '\" ICP_PROP_XICS\n+                                \"' not found: \");\n         return;\n     }\n \n@@ -329,8 +330,9 @@ static void icp_realize(DeviceState *dev, Error **errp)\n \n     obj = object_property_get_link(OBJECT(dev), ICP_PROP_CPU, &err);\n     if (!obj) {\n-        error_propagate(errp, err);\n-        error_prepend(errp, \"required link '\" ICP_PROP_CPU \"' not found: \");\n+        error_propagate_prepend(errp, err,\n+                                \"required link '\" ICP_PROP_CPU\n+                                \"' not found: \");\n         return;\n     }\n \n@@ -624,8 +626,9 @@ static void ics_base_realize(DeviceState *dev, Error **errp)\n \n     obj = object_property_get_link(OBJECT(dev), ICS_PROP_XICS, &err);\n     if (!obj) {\n-        error_propagate(errp, err);\n-        error_prepend(errp, \"required link '\" ICS_PROP_XICS \"' not found: \");\n+        error_propagate_prepend(errp, err,\n+                                \"required link '\" ICS_PROP_XICS\n+                                \"' not found: \");\n         return;\n     }\n     ics->xics = XICS_FABRIC(obj);\ndiff --git a/hw/ppc/pnv_core.c b/hw/ppc/pnv_core.c\nindex 9750464bf4..ad1bcc7990 100644\n--- a/hw/ppc/pnv_core.c\n+++ b/hw/ppc/pnv_core.c\n@@ -148,8 +148,8 @@ static void pnv_core_realize(DeviceState *dev, Error **errp)\n \n     chip = object_property_get_link(OBJECT(dev), \"chip\", &local_err);\n     if (!chip) {\n-        error_propagate(errp, local_err);\n-        error_prepend(errp, \"required link 'chip' not found: \");\n+        error_propagate_prepend(errp, local_err,\n+                                \"required link 'chip' not found: \");\n         return;\n     }\n \ndiff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c\nindex c2271e6ed4..58afa46204 100644\n--- a/hw/ppc/spapr_pci.c\n+++ b/hw/ppc/spapr_pci.c\n@@ -1724,16 +1724,15 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)\n         if (smc->legacy_irq_allocation) {\n             irq = spapr_irq_findone(spapr, &local_err);\n             if (local_err) {\n-                error_propagate(errp, local_err);\n-                error_prepend(errp, \"can't allocate LSIs: \");\n+                error_propagate_prepend(errp, local_err,\n+                                        \"can't allocate LSIs: \");\n                 return;\n             }\n         }\n \n         spapr_irq_claim(spapr, irq, true, &local_err);\n         if (local_err) {\n-            error_propagate(errp, local_err);\n-            error_prepend(errp, \"can't allocate LSIs: \");\n+            error_propagate_prepend(errp, local_err, \"can't allocate LSIs: \");\n             return;\n         }\n \ndiff --git a/hw/timer/aspeed_timer.c b/hw/timer/aspeed_timer.c\nindex 54b400b94a..5c786e5128 100644\n--- a/hw/timer/aspeed_timer.c\n+++ b/hw/timer/aspeed_timer.c\n@@ -454,8 +454,7 @@ static void aspeed_timer_realize(DeviceState *dev, Error **errp)\n \n     obj = object_property_get_link(OBJECT(dev), \"scu\", &err);\n     if (!obj) {\n-        error_propagate(errp, err);\n-        error_prepend(errp, \"required link 'scu' not found: \");\n+        error_propagate_prepend(errp, err, \"required link 'scu' not found: \");\n         return;\n     }\n     s->scu = ASPEED_SCU(obj);\ndiff --git a/hw/usb/bus.c b/hw/usb/bus.c\nindex 11f7720d71..bf796d67e6 100644\n--- a/hw/usb/bus.c\n+++ b/hw/usb/bus.c\n@@ -340,8 +340,9 @@ static USBDevice *usb_try_create_simple(USBBus *bus, const char *name,\n     }\n     object_property_set_bool(OBJECT(dev), true, \"realized\", &err);\n     if (err) {\n-        error_propagate(errp, err);\n-        error_prepend(errp, \"Failed to initialize USB device '%s': \", name);\n+        error_propagate_prepend(errp, err,\n+                                \"Failed to initialize USB device '%s': \",\n+                                name);\n         return NULL;\n     }\n     return dev;\ndiff --git a/hw/vfio/pci.c b/hw/vfio/pci.c\nindex 8b73582d51..4404c28360 100644\n--- a/hw/vfio/pci.c\n+++ b/hw/vfio/pci.c\n@@ -1283,8 +1283,7 @@ static int vfio_msi_setup(VFIOPCIDevice *vdev, int pos, Error **errp)\n         if (ret == -ENOTSUP) {\n             return 0;\n         }\n-        error_prepend(&err, \"msi_init failed: \");\n-        error_propagate(errp, err);\n+        error_propagate_prepend(errp, err, \"msi_init failed: \");\n         return ret;\n     }\n     vdev->msi_cap_size = 0xa + (msi_maskbit ? 0xa : 0) + (msi_64bit ? 0x4 : 0);\ndiff --git a/include/qapi/error.h b/include/qapi/error.h\nindex bcb86a79f5..51b63dd4b5 100644\n--- a/include/qapi/error.h\n+++ b/include/qapi/error.h\n@@ -52,8 +52,12 @@\n  * where Error **errp is a parameter, by convention the last one.\n  *\n  * Pass an existing error to the caller with the message modified:\n+ *     error_propagate_prepend(errp, err);\n+ *\n+ * Avoid\n  *     error_propagate(errp, err);\n  *     error_prepend(errp, \"Could not frobnicate '%s': \", name);\n+ * because this fails to prepend when @errp is &error_fatal.\n  *\n  * Create a new error and pass it to the caller:\n  *     error_setg(errp, \"situation normal, all fouled up\");\n@@ -215,6 +219,16 @@ void error_setg_win32_internal(Error **errp,\n  */\n void error_propagate(Error **dst_errp, Error *local_err);\n \n+\n+/*\n+ * Propagate error object (if any) with some text prepended.\n+ * Behaves like\n+ *     error_prepend(&local_err, fmt, ...);\n+ *     error_propagate(dst_errp, local_err);\n+ */\n+void error_propagate_prepend(Error **dst_errp, Error *local_err,\n+                             const char *fmt, ...);\n+\n /*\n  * Prepend some text to @errp's human-readable error message.\n  * The text is made by formatting @fmt, @ap like vprintf().\ndiff --git a/migration/migration.c b/migration/migration.c\nindex d6ae879dc8..f0f299a773 100644\n--- a/migration/migration.c\n+++ b/migration/migration.c\n@@ -1546,9 +1546,9 @@ static GSList *migration_blockers;\n int migrate_add_blocker(Error *reason, Error **errp)\n {\n     if (migrate_get_current()->only_migratable) {\n-        error_propagate(errp, error_copy(reason));\n-        error_prepend(errp, \"disallowing migration blocker \"\n-                          \"(--only_migratable) for: \");\n+        error_propagate_prepend(errp, error_copy(reason),\n+                                \"disallowing migration blocker \"\n+                                \"(--only_migratable) for: \");\n         return -EACCES;\n     }\n \n@@ -1557,9 +1557,9 @@ int migrate_add_blocker(Error *reason, Error **errp)\n         return 0;\n     }\n \n-    error_propagate(errp, error_copy(reason));\n-    error_prepend(errp, \"disallowing migration blocker (migration in \"\n-                      \"progress) for: \");\n+    error_propagate_prepend(errp, error_copy(reason),\n+                            \"disallowing migration blocker \"\n+                            \"(migration in progress) for: \");\n     return -EBUSY;\n }\n \ndiff --git a/util/error.c b/util/error.c\nindex 3efdd69162..b5ccbd8eac 100644\n--- a/util/error.c\n+++ b/util/error.c\n@@ -292,3 +292,16 @@ void error_propagate(Error **dst_errp, Error *local_err)\n         error_free(local_err);\n     }\n }\n+\n+void error_propagate_prepend(Error **dst_errp, Error *err,\n+                             const char *fmt, ...)\n+{\n+    va_list ap;\n+\n+    if (dst_errp && !*dst_errp) {\n+        va_start(ap, fmt);\n+        error_vprepend(&err, fmt, ap);\n+        va_end(ap);\n+    } /* else error is being ignored, don't bother with prepending */\n+    error_propagate(dst_errp, err);\n+}\n",
    "prefixes": [
        "v4",
        "01/38"
    ]
}