> Hello All, > > I am debugging a problem which I do not know how to solve. I know what > is happening, but cannot find solution to it. If anyone has any > suggestions or solution that would be really grateful and I appreciate > it. > > Here is the description. > > I have a thread which spawns a child process using fork() and in child > context it execv to shell and parent thread waits on waitpid(). This > child process is nothing but a shell /bin/sh, so that from program I > can create shell and run some commands. > In this shell instance, I run tshark for capturing network traffic. I > have really high traffic going, so system is really busy. All is good > so far, but when I send SIGKILL to child process (shell) from another > thread from same application, > child process (shell) gets terminated and tshark is assigned to > init(1) process as orphan. The parent thread which spawned the child > process unblocks from waitpid() after cleaning child instance and > continues it execution. > > Here is the problem: > Once the parent thread resumes from waitpid(), it hits fprintf to > print message "exiting from shell" to console. In here the main thread > gets blocked in __kernel_vsyscall () entered from fprintf. Following > is my stack trace from gdb. > But after some more debugging and found that, if I kill from another > shell "tshark" process which is assigned to init(1) as child, the > parent thread unblocks from __kernel_vsyscall (). > > Can anyone tell what is going on, is this related to futex spinning > problem where lock is been held by tshark. How would I approach this > problem? > Or is there a way to kill all child process of a process without > making them orphan. Because when a child process is running at the > time parent is exiting, that child process is assigned to init(1) as > orphan process. > Can this behavior be modified. Please let me know any suggestions and > thoughts. Thanks in advance. > > -- > Regards, > Sri. > > (gdb) backtrace > #0 0xffffe424 in __kernel_vsyscall () > #1 0xb7e6396b in write () from /lib/libc.so.6 > #2 0xb7e0c2ef in _IO_new_file_write () from /lib/libc.so.6 > #3 0xb7e0bf93 in new_do_write () from /lib/libc.so.6 > #4 0xb7e0c296 in _IO_new_do_write () from /lib/libc.so.6 > #5 0xb7e0ce20 in _IO_new_file_overflow () from /lib/libc.so.6 > #6 0xb7e0c0cd in _IO_new_file_xsputn () from /lib/libc.so.6 > #7 0xb7de3634 in vfprintf () from /lib/libc.so.6 > #8 0x09ad62a2 in acme_fprintf (stream=0xb7ee2560, > format=0x9f17694 "shell exited. returning to acli\n") > at /home/svemulpali/cc/svemulpali_SCOTTY_main/linux/private/common/src/coutOverride.cpp:42 > #9 0x094a9345 in vxShellCmdStartWait (syscmd=0x0) > at /home/svemulpali/cc/svemulpali_SCOTTY_main/linux/private/lib/stub/vxShellLib.cpp:210 -- Regards, Sri. -- To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs
