[dpdk-dev] [PATCH v2] mk: fix parallel build of test resources

[Thomas Monjalon <thomas.monjalon@6wind.com>]

The build was failing sometimes when building with multiple
parallel jobs:
    # rm build/build/app/test/*res*
    # make -j6
    objcopy: 'resource.tmp': No such file

The reason is that each resource was built from the same temporary file.
The failure is seen because of a race condition when removing the
temporary file after each resource creation.
It also means that some resources may be created from the wrong source.

The fix is to have a different input file for each resource.
The source file is not directly used because it may have a long path
which is used by objcopy to name the symbols after some transformations.
When linking a tar resource, the input file is already in the current
directory. The hard case is for simply linked resources.
The trick is to create a symbolic link of the source file if it is not
already in the current build directory.
Then there is a replacement of dot by an underscore to predict the
symbol names computed by objcopy which must be redefined.

There is an additional change for the test_resource_c which is both
a real source file and a test resource. An intermediate file
test_resource.res is created to avoid compiling resource.c from the
wrong directory through a symbolic link.

Fixes: 1e9e0a6270 ("app/test: fix resource creation with objcopy on FreeBSD")

Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
---
v2: fix rebuild error due to link test_resource.c in build directory
---
 app/test/Makefile | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/app/test/Makefile b/app/test/Makefile
index 9fa03fb..1f24dd6 100644
--- a/app/test/Makefile
+++ b/app/test/Makefile
@@ -43,14 +43,14 @@ define linked_resource
 SRCS-y += $(1).res.o
 $(1).res.o: $(2)
 	@  echo '  MKRES $$@'
-	$Q ln -fs $$< resource.tmp
+	$Q [ "$$(<D)" = . ] || ln -fs $$<
 	$Q $(OBJCOPY) -I binary -B $(RTE_OBJCOPY_ARCH) -O $(RTE_OBJCOPY_TARGET) \
 		--rename-section                                         \
 			.data=.rodata,alloc,load,data,contents,readonly  \
-		--redefine-sym _binary_resource_tmp_start=beg_$(1)       \
-		--redefine-sym _binary_resource_tmp_end=end_$(1)         \
-		--redefine-sym _binary_resource_tmp_size=siz_$(1)        \
-		resource.tmp $$@ && rm -f resource.tmp
+		--redefine-sym _binary_$$(subst .,_,$$(<F))_start=beg_$(1) \
+		--redefine-sym _binary_$$(subst .,_,$$(<F))_end=end_$(1)   \
+		--redefine-sym _binary_$$(subst .,_,$$(<F))_size=siz_$(1)  \
+		$$(<F) $$@
 endef
 
 ifeq ($(CONFIG_RTE_APP_TEST_RESOURCE_TAR),y)
@@ -76,7 +76,9 @@ SRCS-$(CONFIG_RTE_LIBRTE_CMDLINE) := commands.c
 SRCS-y += test.c
 SRCS-y += resource.c
 SRCS-y += test_resource.c
-$(eval $(call linked_resource,test_resource_c,resource.c))
+test_resource.res: test_resource.c
+	@ cp $< $@
+$(eval $(call linked_resource,test_resource_c,test_resource.res))
 $(eval $(call linked_tar_resource,test_resource_tar,test_resource.c))
 SRCS-$(CONFIG_RTE_APP_TEST_RESOURCE_TAR) += test_pci.c
 $(eval $(call linked_tar_resource,test_pci_sysfs,test_pci_sysfs))
-- 
2.7.0