kernel/samples/watch_queue/Makefile, branch linux-6.12.y

kbuild: introduce hostprogs-always-y and userprogs-always-y

2020-08-09T16:32:59Z

To build host programs, you need to add the program names to 'hostprogs' to use the necessary build rule, but it is not enough to build them because there is no dependency. There are two types of host programs: built as the prerequisite of another (e.g. gen_crc32table in lib/Makefile), or always built when Kbuild visits the Makefile (e.g. genksyms in scripts/genksyms/Makefile). The latter is typical in Makefiles under scripts/, which contains host programs globally used during the kernel build. To build them, you need to add them to both 'hostprogs' and 'always-y'. This commit adds hostprogs-always-y as a shorthand. The same applies to user programs. net/bpfilter/Makefile builds bpfilter_umh on demand, hence always-y is unneeded. In contrast, programs under samples/ are added to both 'userprogs' and 'always-y' so they are always built when Kbuild visits the Makefiles. userprogs-always-y works as a shorthand. Signed-off-by: Masahiro Yamada Acked-by: Miguel Ojeda

samples: watch_queue: build sample program for target architecture

2020-06-21T16:56:09Z

This userspace program includes UAPI headers exported to usr/include/. 'make headers' always works for the target architecture (i.e. the same architecture as the kernel), so the sample program should be built for the target as well. Kbuild now supports 'userprogs' for that. I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because $(CC) may not provide libc. Signed-off-by: Masahiro Yamada

Add sample notification program

2020-05-19T14:38:07Z

The sample program is run like: ./samples/watch_queue/watch_test and watches "/" for mount changes and the current session keyring for key changes: # keyctl add user a a @s 1035096409 # keyctl unlink 1035096409 @s producing: # ./watch_test read() = 16 NOTIFY[000]: ty=000001 sy=02 i=00000110 KEY 2ffc2e5d change=2[linked] aux=1035096409 read() = 16 NOTIFY[000]: ty=000001 sy=02 i=00000110 KEY 2ffc2e5d change=3[unlinked] aux=1035096409 Other events may be produced, such as with a failing disk: read() = 22 NOTIFY[000]: ty=000003 sy=02 i=00000416 USB 3-7.7 dev-reset e=0 r=0 read() = 24 NOTIFY[000]: ty=000002 sy=06 i=00000418 BLOCK 00800050 e=6[critical medium] s=64000ef8 This corresponds to: blk_update_request: critical medium error, dev sdf, sector 1677725432 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0 in dmesg. Signed-off-by: David Howells