Re: [PATCH bpf-next] selftests/bpf: fix test_bpffs

[Yonghong Song <yonghong.song@xxxxxxxxx>]

On 10/27/23 3:30 PM, Manu Bretelle wrote:
> Currently this tests tries to umount /sys/kernel/debug (TDIR) but the
> system it is running on may have mounts below.
>
> For example, danobi/vmtest [0] VMs have
>      mount -t tracefs tracefs /sys/kernel/debug/tracing
> as part of their init.
>
> This change instead creates a "random" directory under /tmp and uses this
> as TDIR.
> If the directory already exists, ignore the error and keep moving on.
>
> Test:
>
> Originally:
>
>      $ vmtest -k $KERNEL_REPO/arch/x86_64/boot/bzImage "./test_progs -vv -a test_bpffs"
>      => bzImage
>      ===> Booting
>      ===> Setting up VM
>      ===> Running command
>      [    2.138818] bpf_testmod: loading out-of-tree module taints kernel.
>      [    2.140913] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
>      bpf_testmod.ko is already unloaded.
>      Loading bpf_testmod.ko...
>      Successfully loaded bpf_testmod.ko.
>      test_test_bpffs:PASS:clone 0 nsec
>      fn:PASS:unshare 0 nsec
>      fn:PASS:mount / 0 nsec
>      fn:FAIL:umount /sys/kernel/debug unexpected error: -1 (errno 16)
>      bpf_testmod.ko is already unloaded.
>      Loading bpf_testmod.ko...
>      Successfully loaded bpf_testmod.ko.
>      test_test_bpffs:PASS:clone 0 nsec
>      test_test_bpffs:PASS:waitpid 0 nsec
>      test_test_bpffs:FAIL:bpffs test  failed 255#282     test_bpffs:FAIL
>      Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED
>      Successfully unloaded bpf_testmod.ko.
>      Command failed with exit code: 1
>
> After this change:
>
>      $ vmtest -k $KERNEL_REPO/arch/x86_64/boot/bzImage "./test_progs -vv -a test_bpffs"
>      => bzImage
>      ===> Booting
>      ===> Setting up VM
>      ===> Running command
>      [    2.119236] bpf_testmod: loading out-of-tree module taints kernel.
>      [    2.121768] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
>      bpf_testmod.ko is already unloaded.
>      Loading bpf_testmod.ko...
>      Successfully loaded bpf_testmod.ko.
>      test_test_bpffs:PASS:clone 0 nsec
>      fn:PASS:unshare 0 nsec
>      fn:PASS:mount / 0 nsec
>      fn:PASS:mount tmpfs 0 nsec
>      fn:PASS:mkdir /tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1 0 nsec
>      fn:PASS:mkdir /tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs2 0 nsec
>      fn:PASS:mount bpffs /tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1 0 nsec
>      fn:PASS:mount bpffs /tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs2 0 nsec
>      fn:PASS:reading /tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1/maps.debug 0 nsec
>      fn:PASS:reading /tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs2/progs.debug 0 nsec
>      fn:PASS:creating /tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1/a 0 nsec
>      fn:PASS:creating /tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1/a/1 0 nsec
>      fn:PASS:creating /tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1/b 0 nsec
>      fn:PASS:create_map(ARRAY) 0 nsec
>      fn:PASS:pin map 0 nsec
>      fn:PASS:stat(/tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1/a) 0 nsec
>      fn:PASS:renameat2(/fs1/a, /fs1/b, RENAME_EXCHANGE) 0 nsec
>      fn:PASS:stat(/tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1/b) 0 nsec
>      fn:PASS:b should have a's inode 0 nsec
>      fn:PASS:access(/tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1/b/1) 0 nsec
>      fn:PASS:stat(/tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1/map) 0 nsec
>      fn:PASS:renameat2(/fs1/c, /fs1/b, RENAME_EXCHANGE) 0 nsec
>      fn:PASS:stat(/tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1/b) 0 nsec
>      fn:PASS:b should have c's inode 0 nsec
>      fn:PASS:access(/tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1/c/1) 0 nsec
>      fn:PASS:renameat2(RENAME_NOREPLACE) 0 nsec
>      fn:PASS:access(/tmp/vvnlhrgunvkrfegnlrvnggcudfgdtrhbfelkebeurfed/fs1/b) 0 nsec
>      bpf_testmod.ko is already unloaded.
>      Loading bpf_testmod.ko...
>      Successfully loaded bpf_testmod.ko.
>      test_test_bpffs:PASS:clone 0 nsec
>      test_test_bpffs:PASS:waitpid 0 nsec
>      test_test_bpffs:PASS:bpffs test  0 nsec
>      #282     test_bpffs:OK
>      Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
>      Successfully unloaded bpf_testmod.ko.
>
> [0] https://github.com/danobi/vmtest
>
> This is a follow-up of https://lore.kernel.org/bpf/20231024201852.1512720-1-chantr4@xxxxxxxxx/T/
>
> Signed-off-by: Manu Bretelle <chantr4@xxxxxxxxx>

Acked-by: Yonghong Song <yonghong.song@xxxxxxxxx>