[PATCH] arm-bsp/boot-firmware: fix build race

[PATCH] arm-bsp/boot-firmware: fix build race

[Ross Burton]

As boot-firmware is heavily based on SCP-firmware it has the same build
race.  Luckily, the patch in SCP-firmware[1] applies cleanly to
boot-firmware.

[1] https://github.com/ARM-software/SCP-firmware/commit/34e1c04534607f5605255f39fb46e26261fc9c4e
Signed-off-by: Ross Burton <ross.burton@arm.com>

Change-Id: Iaa2f1bb71fce66589db530ea378d4ce995a6bed9
---
 .../boot-firmware/gen-module-race.patch       | 66 +++++++++++++++++++
 .../boot-firmware/boot-firmware_git.bb        |  3 +-
 2 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 meta-arm-bsp/recipes-bsp/boot-firmware/boot-firmware/gen-module-race.patch

diff --git a/meta-arm-bsp/recipes-bsp/boot-firmware/boot-firmware/gen-module-race.patch b/meta-arm-bsp/recipes-bsp/boot-firmware/boot-firmware/gen-module-race.patch
new file mode 100644
index 0000000..c93e91a
--- /dev/null
+++ b/meta-arm-bsp/recipes-bsp/boot-firmware/boot-firmware/gen-module-race.patch
@@ -0,0 +1,66 @@
+Upstream-Status: Pending
+Signed-off-by: Ross Burton <ross.burton@arm.com>
+
+From 34e1c04534607f5605255f39fb46e26261fc9c4e Mon Sep 17 00:00:00 2001
+From: Ross Burton <ross.burton@arm.com>
+Date: Tue, 8 Sep 2020 11:49:08 +0100
+Subject: [PATCH] tools/gen_module_code: atomically rewrite the generated files
+
+The gen_module rule in rules.mk is marked as .PHONY, so make will
+execute it whenever it is mentioned. This results in gen_module_code
+being executed 64 times for a Juno build.
+
+However in heavily parallel builds there's a good chance that
+gen_module_code is writing a file whilst the compiler is reading it
+because make also doesn't know what files are generated by
+gen_module_code.
+
+The correct fix is to adjust the Makefiles so that the dependencies are
+correct but this isn't trivial, so band-aid the problem by atomically
+writing the generated files.
+
+Change-Id: I82d44f9ea6537a91002e1f80de8861d208571630
+Signed-off-by: Ross Burton <ross.burton@arm.com>
+---
+ tools/gen_module_code.py | 19 ++++++++++++++-----
+ 1 file changed, 14 insertions(+), 5 deletions(-)
+
+diff --git a/tools/gen_module_code.py b/tools/gen_module_code.py
+index 7b3953845..ee099b713 100755
+--- a/tools/gen_module_code.py
++++ b/tools/gen_module_code.py
+@@ -17,6 +17,7 @@
+ import argparse
+ import os
+ import sys
++import tempfile
+ 
+ DEFAULT_PATH = 'build/'
+ 
+@@ -53,13 +54,21 @@
+ 
+ def generate_file(path, filename, content):
+     full_filename = os.path.join(path, filename)
+-    with open(full_filename, 'a+') as f:
+-        f.seek(0)
+-        if f.read() != content:
++
++    try:
++        with open(full_filename) as f:
++            rewrite = f.read() != content
++    except FileNotFoundError:
++        rewrite = True
++
++    if rewrite:
++        with tempfile.NamedTemporaryFile(prefix="gen-module-code",
++                                         dir=path,
++                                         delete=False,
++                                         mode="wt") as f:
+             print("[GEN] {}...".format(full_filename))
+-            f.seek(0)
+-            f.truncate()
+             f.write(content)
++        os.replace(f.name, full_filename)
+ 
+ 
+ def generate_header(path, modules):
diff --git a/meta-arm-bsp/recipes-bsp/boot-firmware/boot-firmware_git.bb b/meta-arm-bsp/recipes-bsp/boot-firmware/boot-firmware_git.bb
index c7242d1..c48e586 100644
--- a/meta-arm-bsp/recipes-bsp/boot-firmware/boot-firmware_git.bb
+++ b/meta-arm-bsp/recipes-bsp/boot-firmware/boot-firmware_git.bb
@@ -5,7 +5,8 @@ LICENSE = "BSD-3-Clause & Apache-2.0"
 LIC_FILES_CHKSUM = "file://license.md;md5=e44b2531cd6ffe9dece394dbe988d9a0 \
                     file://cmsis/LICENSE.txt;md5=e3fc50a88d0a364313df4b21ef20c29e"
 
-SRC_URI = "gitsm://git.linaro.org/landing-teams/working/arm/boot-firmware.git;protocol=https"
+SRC_URI = "gitsm://git.linaro.org/landing-teams/working/arm/boot-firmware.git;protocol=https \
+           file://gen-module-race.patch"
 SRCREV = "af7eeb1bb8c5a85a5e5a76d48acc6fe864d715a9"
 PV = "2020.02.10+git${SRCPV}"
 
-- 
2.25.1