[U-Boot,v2] kbuild: fix parallel build race caused by u-boot.cfg regeneration

Message ID 1547129499-20373-1-git-send-email-yamada.masahiro@socionext.com
State Accepted
Delegated to: Tom Rini
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Series
  • [U-Boot,v2] kbuild: fix parallel build race caused by u-boot.cfg regeneration
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Commit Message

Masahiro Yamada Jan. 10, 2019, 2:11 p.m.
Multiple people have reported intermittent build failure in parallel
building.

Kever Yang reported this issue some time ago [1], but I could not
get enough clue at that time.

This time, Richard Purdie provided a full build log [2], which was
very helpful for me to root-cause it.

The cause of the problem is commit 0d982c585330 ("Makefile: add
dependencies to regenerate u-boot.cfg when lost").

That commit added the 'cfg' as the prerequisite of the 'all' target,
so the parallel build tries to run it simultaneously, then regenerates
a symlink while building objects.

When u-boot.cfg is accidentally lost, let's rebuild it before
descending into any subdirectories.

Also, what is annoying is u-boot.cfg is currently regenerated every
time since it depends on FORCE. We can get rid of all the prerequisites
of u-boot.cfg because u-boot.cfg is rebuilt anyway as the byproduct of
auto.conf when a user updates the .config file.

[1] https://lists.denx.de/pipermail/u-boot/2018-June/330341.html
[2] https://autobuilder.yoctoproject.org/typhoon/#/builders/65/builds/160/steps/7/logs/step1b

Fixes: 0d982c585330 ("Makefile: add dependencies to regenerate u-boot.cfg when lost")
Reported-by: Kever Yang <kever.yang@rock-chips.com>
Reported-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
---

Changes in v2:
 - Move 'cfg' before 'prepare0' to avoid a race between them

 Makefile | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Tom Rini Jan. 16, 2019, 2:44 a.m. | #1
On Thu, Jan 10, 2019 at 11:11:39PM +0900, Masahiro Yamada wrote:

> Multiple people have reported intermittent build failure in parallel
> building.
> 
> Kever Yang reported this issue some time ago [1], but I could not
> get enough clue at that time.
> 
> This time, Richard Purdie provided a full build log [2], which was
> very helpful for me to root-cause it.
> 
> The cause of the problem is commit 0d982c585330 ("Makefile: add
> dependencies to regenerate u-boot.cfg when lost").
> 
> That commit added the 'cfg' as the prerequisite of the 'all' target,
> so the parallel build tries to run it simultaneously, then regenerates
> a symlink while building objects.
> 
> When u-boot.cfg is accidentally lost, let's rebuild it before
> descending into any subdirectories.
> 
> Also, what is annoying is u-boot.cfg is currently regenerated every
> time since it depends on FORCE. We can get rid of all the prerequisites
> of u-boot.cfg because u-boot.cfg is rebuilt anyway as the byproduct of
> auto.conf when a user updates the .config file.
> 
> [1] https://lists.denx.de/pipermail/u-boot/2018-June/330341.html
> [2] https://autobuilder.yoctoproject.org/typhoon/#/builders/65/builds/160/steps/7/logs/step1b
> 
> Fixes: 0d982c585330 ("Makefile: add dependencies to regenerate u-boot.cfg when lost")
> Reported-by: Kever Yang <kever.yang@rock-chips.com>
> Reported-by: Richard Purdie <richard.purdie@linuxfoundation.org>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> Reviewed-by: Simon Glass <sjg@chromium.org>

Applied to u-boot/master, thanks!

Patch

diff --git a/Makefile b/Makefile
index eeb299f..c6eb727 100644
--- a/Makefile
+++ b/Makefile
@@ -534,7 +534,7 @@  include/config/%.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
 	@# Otherwise, 'make silentoldconfig' would be invoked twice.
 	$(Q)touch include/config/auto.conf
 
-u-boot.cfg spl/u-boot.cfg tpl/u-boot.cfg: include/config.h FORCE
+u-boot.cfg spl/u-boot.cfg tpl/u-boot.cfg:
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.autoconf $(@)
 
 -include include/autoconf.mk
@@ -910,7 +910,7 @@  quiet_cmd_cfgcheck = CFGCHK  $2
 cmd_cfgcheck = $(srctree)/scripts/check-config.sh $2 \
 		$(srctree)/scripts/config_whitelist.txt $(srctree)
 
-all:		$(ALL-y) cfg
+all:		$(ALL-y)
 ifeq ($(CONFIG_DM_I2C_COMPAT)$(CONFIG_SANDBOX),y)
 	@echo >&2 "===================== WARNING ======================"
 	@echo >&2 "This board uses CONFIG_DM_I2C_COMPAT. Please remove"
@@ -1530,7 +1530,7 @@  ifneq ($(KBUILD_SRC),)
 endif
 
 # prepare2 creates a makefile if using a separate output directory
-prepare2: prepare3 outputmakefile
+prepare2: prepare3 outputmakefile cfg
 
 prepare1: prepare2 $(version_h) $(timestamp_h) \
                    include/config/auto.conf