Originally, bpfilter_umh was linked with -static only when CONFIG_BPFILTER_UMH=y. Commit8a2cc0505c("bpfilter: use 'userprogs' syntax to build bpfilter_umh") silently, accidentally dropped the CONFIG_BPFILTER_UMH=y test in the Makefile. Revive it in order to link it dynamically when CONFIG_BPFILTER_UMH=m. Since commitb1183b6dca("bpfilter: check if $(CC) can link static libc in Kconfig"), the compiler must be capable of static linking to enable CONFIG_BPFILTER_UMH, but it requires more than needed. To loosen the compiler requirement, I changed the dependency as follows: depends on CC_CAN_LINK depends on m || CC_CAN_LINK_STATIC If CONFIG_CC_CAN_LINK_STATIC in unset, CONFIG_BPFILTER_UMH is restricted to 'm' or 'n'. In theory, CONFIG_CC_CAN_LINK is not required for CONFIG_BPFILTER_UMH=y, but I did not come up with a good way to describe it. Fixes:8a2cc0505c("bpfilter: use 'userprogs' syntax to build bpfilter_umh") Reported-by: Michal Kubecek <mkubecek@suse.cz> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Tested-by: Michal Kubecek <mkubecek@suse.cz> Link: https://lore.kernel.org/bpf/20200701092644.762234-1-masahiroy@kernel.org
		
			
				
	
	
		
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| # SPDX-License-Identifier: GPL-2.0-only
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| menuconfig BPFILTER
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| 	bool "BPF based packet filtering framework (BPFILTER)"
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| 	depends on NET && BPF && INET
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| 	help
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| 	  This builds experimental bpfilter framework that is aiming to
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| 	  provide netfilter compatible functionality via BPF
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| 
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| if BPFILTER
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| config BPFILTER_UMH
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| 	tristate "bpfilter kernel module with user mode helper"
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| 	depends on CC_CAN_LINK
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| 	depends on m || CC_CAN_LINK_STATIC
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| 	default m
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| 	help
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| 	  This builds bpfilter kernel module with embedded user mode helper
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| 
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| 	  Note: To compile this as built-in, your toolchain must support
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| 	  building static binaries, since rootfs isn't mounted at the time
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| 	  when __init functions are called and do_execv won't be able to find
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| 	  the elf interpreter.
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| endif
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