[PATCH-for-5.1 v3 02/24] scripts/coccinelle: Script to simplify DeviceClass error propagation

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

When a device uses an Error* with data not modified before realize(),
this call can be moved to init(). Add a Coccinelle patch to find such
uses.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 ...implify-init-realize-error_propagate.cocci | 69 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 70 insertions(+)
 create mode 100644 scripts/coccinelle/simplify-init-realize-error_propagate.cocci

diff --git a/scripts/coccinelle/simplify-init-realize-error_propagate.cocci b/scripts/coccinelle/simplify-init-realize-error_propagate.cocci
new file mode 100644
index 0000000000..2e3ec4d98a
--- /dev/null
+++ b/scripts/coccinelle/simplify-init-realize-error_propagate.cocci
@@ -0,0 +1,69 @@
+// Find error-propagation calls that don't need to be in DeviceClass::realize()
+// because they don't use information user can change before calling realize(),
+// so they can be moved to DeviceClass:initfn() where error propagation is not
+// needed.
+//
+// Copyright: (C) 2020 Philippe Mathieu-Daudé
+// This work is licensed under the terms of the GNU GPLv2 or later.
+//
+// spatch \
+//  --macro-file scripts/cocci-macro-file.h \
+//  --sp-file \
+//    scripts/coccinelle/simplify-init-realize-error_propagate.cocci \
+//  --timeout 60
+//
+// Inspired by https://www.mail-archive.com/qemu-devel@nongnu.org/msg692500.html
+
+
+@ match_class_init @
+TypeInfo info;
+identifier class_initfn;
+@@
+    info.class_init = class_initfn;
+
+
+@ match_instance_init @
+TypeInfo info;
+identifier instance_initfn;
+@@
+    info.instance_init = instance_initfn;
+
+
+@ match_realize @
+identifier match_class_init.class_initfn;
+DeviceClass *dc;
+identifier realizefn;
+@@
+void class_initfn(...)
+{
+    ...
+    dc->realize = realizefn;
+    ...
+}
+
+
+@ propagate_in_realize @
+identifier match_realize.realizefn;
+identifier err;
+identifier errp;
+identifier func_with_errp =~ "(?!object_property_set_link)";
+symbol error_abort, error_fatal;
+position pos;
+@@
+void realizefn@pos(..., Error **errp)
+{
+    ...
+    Error *err = NULL;
+    <+...
+    func_with_errp(..., \(&error_abort\|&error_fatal\));
+    ...+>
+}
+
+
+@ script:python @
+initfn << match_instance_init.instance_initfn;
+realizefn << match_realize.realizefn;
+p << propagate_in_realize.pos;
+@@
+print('>>> possible moves from {}() to {}() in {}:{}'
+      .format(initfn, realizefn, p[0].file, p[0].line))
diff --git a/MAINTAINERS b/MAINTAINERS
index 642c8e0b6b..6203543ec0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2058,6 +2058,7 @@ F: scripts/coccinelle/err-bad-newline.cocci
 F: scripts/coccinelle/error-use-after-free.cocci
 F: scripts/coccinelle/error_propagate_null.cocci
 F: scripts/coccinelle/remove_local_err.cocci
+F: scripts/coccinelle/simplify-init-realize-error_propagate.cocci
 F: scripts/coccinelle/use-error_fatal.cocci
 
 GDB stub
-- 
2.21.1