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Bash 4.4, released in 2016, supports 'wait $!' to check the exit status
of a process substitution, but it seems too new.
Some people using older bash versions (on CentOS 7, Ubuntu 16.04, etc.)
reported an error like this:
./scripts/check-local-export: line 54: wait: pid 17328 is not a child of this shell
I used the process substitution to avoid a pipeline, which executes each
command in a subshell. If the while-loop is executed in the subshell
context, variable changes within are lost after the subshell terminates.
Fortunately, Bash 4.2, released in 2011, supports the 'lastpipe' option,
which makes the last element of a pipeline run in the current shell process.
Switch to the pipeline with 'lastpipe' solution, and also set 'pipefail'
to catch errors from ${NM}.
Add the bash requirement to Documentation/process/changes.rst.
Fixes: 31cb50b5590f ("kbuild: check static EXPORT_SYMBOL* by script instead of modpost")
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Reported-by: Wang Yugui <wangyugui@e16-tech.com>
Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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The 'static' specifier and EXPORT_SYMBOL() are an odd combination.
Commit 15bfc2348d54 ("modpost: check for static EXPORT_SYMBOL*
functions") tried to detect it, but this check has false negatives.
Here is the sample code.
Makefile:
obj-y += foo1.o foo2.o
foo1.c:
#include <linux/export.h>
static void foo(void) {}
EXPORT_SYMBOL(foo);
foo2.c:
void foo(void) {}
foo1.c exports the static symbol 'foo', but modpost cannot catch it
because it is fooled by foo2.c, which has a global symbol with the
same name.
s->is_static is cleared if a global symbol with the same name is found
somewhere, but EXPORT_SYMBOL() and the global symbol do not necessarily
belong to the same compilation unit.
This check should be done per compilation unit, but I do not know how
to do it in modpost. modpost runs against vmlinux.o or modules, which
merges multiple objects, then forgets their origin.
modpost cannot parse individual objects because they may not be ELF but
LLVM IR when CONFIG_LTO_CLANG=y.
Add a simple bash script to parse the output from ${NM}. This works for
CONFIG_LTO_CLANG=y because llvm-nm can dump symbols of LLVM IR files.
Revert 15bfc2348d54.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
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Masahiro Yamada
Schspa Shi