linux-next/samples
Eduard Zingerman 5a6ea7022f samples/bpf: Remove unnecessary -I flags from libbpf EXTRA_CFLAGS
Commit [0] breaks samples/bpf build:

    $ make M=samples/bpf
    ...
    make -C /path/to/kernel/samples/bpf/../../tools/lib/bpf \
     ...
     EXTRA_CFLAGS=" \
     ...
     -fsanitize=bounds \
     -I/path/to/kernel/usr/include \
     ...
    	/path/to/kernel/samples/bpf/libbpf/libbpf.a install_headers
      CC      /path/to/kernel/samples/bpf/libbpf/staticobjs/libbpf.o
    In file included from libbpf.c:29:
    /path/to/kernel/tools/include/linux/err.h:35:8: error: 'inline' can only appear on functions
       35 | static inline void * __must_check ERR_PTR(long error_)
          |        ^

The error is caused by `objtree` variable changing definition from `.`
(dot) to an absolute path:
- The variable TPROGS_CFLAGS is constructed as follows:
  ...
  TPROGS_CFLAGS += -I$(objtree)/usr/include
- It is passed as EXTRA_CFLAGS for libbpf compilation:
  $(LIBBPF): ...
    ...
	$(MAKE) -C $(LIBBPF_SRC) RM='rm -rf' EXTRA_CFLAGS="$(TPROGS_CFLAGS)"
- Before commit [0], the line passed to libbpf makefile was
  '-I./usr/include', where '.' referred to LIBBPF_SRC due to -C flag.
  The directory $(LIBBPF_SRC)/usr/include does not exist and thus
  was never resolved by C compiler.
- After commit [0], the line passed to libbpf makefile became:
  '<output-dir>/usr/include', this directory exists and is resolved by
  C compiler.
- Both 'tools/include' and 'usr/include' define files err.h and types.h.
- libbpf expects headers like 'linux/err.h' and 'linux/types.h'
  defined in 'tools/include', not 'usr/include', hence the compilation
  error.

This commit removes unnecessary -I flags from libbpf compilation.
(libbpf sets up the necessary includes at lib/bpf/Makefile:63).

Changes v1 [1] -> v2:
- dropped unnecessary replacement of KBUILD_OUTPUT with $(objtree)
  (Andrii)
Changes v2 [2] -> v3:
- make sure --sysroot option is set for libbpf's EXTRA_CFLAGS,
  if $(SYSROOT) is set (Stanislav)

[0] commit 13b25489b6 ("kbuild: change working directory to external module directory with M=")
[1] https://lore.kernel.org/bpf/20241202212154.3174402-1-eddyz87@gmail.com/
[2] https://lore.kernel.org/bpf/20241202234741.3492084-1-eddyz87@gmail.com/

Fixes: 13b25489b6 ("kbuild: change working directory to external module directory with M=")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://lore.kernel.org/bpf/20241203182222.3915763-1-eddyz87@gmail.com
2024-12-03 13:29:04 -08:00
..
acrn virt: acrn: Fix typos 2024-05-04 18:59:44 +02:00
auxdisplay .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
binderfs .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
bpf samples/bpf: Remove unnecessary -I flags from libbpf EXTRA_CFLAGS 2024-12-03 13:29:04 -08:00
cgroup samples/cgroup: add .gitignore file for generated samples 2024-01-24 11:52:40 -08:00
configfs samples: configfs: add missing MODULE_DESCRIPTION() macro 2024-07-10 14:59:01 +02:00
connector .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
coresight coresight: syscfg: Example CoreSight configuration loadable module 2021-11-26 11:34:07 -07:00
fanotify Add gitignore file for samples/fanotify/ subdirectory 2021-11-07 11:19:24 -08:00
fprobe fprobe: add missing MODULE_DESCRIPTION() macro 2024-06-12 08:44:27 +09:00
ftrace samples/ftrace: Add support for ftrace direct samples on powerpc 2024-10-31 11:00:55 +11:00
hid HID: samples: fix the 2 struct_ops definitions 2024-07-05 14:08:31 +02:00
hidraw .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
hw_breakpoint samples/hw_breakpoint: mark sample_hbp as static 2023-07-26 11:17:19 -07:00
kdb kdb: Rename members of struct kdbtab_t 2021-07-27 17:05:06 +01:00
kfifo kfifo: add missing MODULE_DESCRIPTION() macros 2024-06-28 19:36:29 -07:00
kmemleak kmemleak-test: add percpu leak 2024-09-01 20:25:50 -07:00
kobject samples/kobject: add missing MODULE_DESCRIPTION() macros 2024-06-04 18:04:28 +02:00
kprobes samples: kprobes: add missing MODULE_DESCRIPTION() macros 2024-06-12 08:44:27 +09:00
landlock samples/landlock: Clarify option parsing behaviour 2024-10-22 20:43:43 +02:00
livepatch livepatch: Reorder to use before freeing a pointer 2022-03-23 13:51:11 +01:00
mei samples: mei: don't wait on read completion upon write. 2021-08-01 09:54:22 +02:00
nitro_enclaves nitro_enclaves: Add fixes for checkpatch blank line reports 2021-09-14 11:11:20 +02:00
pfsm samples: Add userspace example for TI TPS6594 PFSM 2023-06-15 13:41:53 +02:00
pidfd .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
pktgen samples: pktgen: correct dev to DEV 2024-11-13 18:54:33 -08:00
qmi samples: qmi: Convert to platform remove callback returning void 2024-05-27 10:14:15 +02:00
rpmsg samples/rpmsg: Introduce a module parameter for message count 2019-08-26 22:10:39 -07:00
rust rust: sync: update Arc and UniqueArc to take allocation flags 2024-04-16 22:50:04 +02:00
seccomp samples: user-trap: fix strict-aliasing warning 2024-02-12 10:42:02 -08:00
timers .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
trace_events tracing: Add __print_dynamic_array() helper 2024-10-30 17:24:32 +01:00
trace_printk samples/trace_printk: Wait for IRQ work to finish 2019-12-21 16:08:22 -05:00
uhid kbuild: introduce hostprogs-always-y and userprogs-always-y 2020-08-10 01:32:59 +09:00
user_events tracing/user_events: Use write ABI in example 2023-03-29 06:52:09 -04:00
v4l media: samples: v4l2-pci-skeleton.c: drop vb2_ops_wait_prepare/finish 2024-10-28 09:20:10 +01:00
vfio-mdev [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
vfs .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
watch_queue .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
watchdog .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
Kconfig samples: introduce new samples subdir for cgroup 2023-12-10 16:51:54 -08:00
Makefile samples: introduce new samples subdir for cgroup 2023-12-10 16:51:54 -08:00