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kbuild: check uniqueness of module names
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In the recent build test of linux-next, Stephen saw a build error
caused by a broken .tmp_versions/*.mod file:

  https://lkml.org/lkml/2019/5/13/991

drivers/net/phy/asix.ko and drivers/net/usb/asix.ko have the same
basename, and there is a race in generating .tmp_versions/asix.mod

Kbuild has not checked this before, and it suddenly shows up with
obscure error messages when this kind of race occurs.

Non-unique module names cause various sort of problems, but it is
not trivial to catch them by eyes.

Hence, this script.

It checks not only real modules, but also built-in modules (i.e.
controlled by tristate CONFIG option, but currently compiled with =y).
Non-unique names for built-in modules also cause problems because
/sys/modules/ would fall over.

For the latest kernel, I tested "make allmodconfig all" (or more
quickly "make allyesconfig modules"), and it detected the following:

warning: same basename if the following are built as modules:
  drivers/regulator/88pm800.ko
  drivers/mfd/88pm800.ko
warning: same basename if the following are built as modules:
  drivers/gpu/drm/bridge/adv7511/adv7511.ko
  drivers/media/i2c/adv7511.ko
warning: same basename if the following are built as modules:
  drivers/net/phy/asix.ko
  drivers/net/usb/asix.ko
warning: same basename if the following are built as modules:
  fs/coda/coda.ko
  drivers/media/platform/coda/coda.ko
warning: same basename if the following are built as modules:
  drivers/net/phy/realtek.ko
  drivers/net/dsa/realtek.ko

Reported-by: Stephen Rothwell <[email protected]>
Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Stephen Rothwell <[email protected]>
Reviewed-by: Lucas De Marchi <[email protected]>
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masahir0y committed May 18, 2019
1 parent aff11cd commit 3a48a91
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1 change: 1 addition & 0 deletions Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -1288,6 +1288,7 @@ modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux) modules.builtin
$(Q)$(AWK) '!x[$$0]++' $(vmlinux-dirs:%=$(objtree)/%/modules.order) > $(objtree)/modules.order
@$(kecho) ' Building modules, stage 2.';
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/modules-check.sh

modules.builtin: $(vmlinux-dirs:%=%/modules.builtin)
$(Q)$(AWK) '!x[$$0]++' $^ > $(objtree)/modules.builtin
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16 changes: 16 additions & 0 deletions scripts/modules-check.sh
Original file line number Diff line number Diff line change
@@ -0,0 +1,16 @@
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0

set -e

# Check uniqueness of module names
check_same_name_modules()
{
for m in $(sed 's:.*/::' modules.order modules.builtin | sort | uniq -d)
do
echo "warning: same basename if the following are built as modules:" >&2
sed "/\/$m/!d;s:^kernel/: :" modules.order modules.builtin >&2
done
}

check_same_name_modules

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