Hi folks, Kees

This issue confuses the LKP/0Day robot for a long time. Take below script as an example:

lizj@FNSTPC:~/workspace/colo/linux/tools/testing/selftests$ cat a.sh #!/bin/bash sleep 10 & echo 1000000000000000

lizj@FNSTPC:~/workspace/colo/linux/tools/testing/selftests$ time ./a.sh | ./kselftest/prefix.pl # 1000000000000000

real    0m10.004s user    0m0.012s sys    0m0.001s ------------------------------------

Although the first script already exited,  ./kselftest/prefix.pl will block until "sleep 10 &" exit. That means once some of the child process cannot finish/exit itself, for example, one test becomes *zombie* for some reasons, the whole ksefltest framework will hang forever.

In addition,  currently ksefltest timeout scheme[1][2] will not signal/kil the child processes, that make the blocking often happens.

Since i'm not familiar with perl, not sure whether it can finish itself *directly* when first/front command(excluding child processes) exits.

[1]: https://lkml.org/lkml/2021/12/17/140 [2]: http://lkml.iu.edu/hypermail/linux/kernel/2004.1/02379.html $ man timeout        --foreground               when not running timeout directly from a shell prompt,               allow COMMAND to read from the TTY and get TTY signals; in this mode, children of COMMAND will not be timed out

Thanks Zhijian