[Bug 764621] Re: /usr/lib/firefox-4.0/plugin-container hangs upon Firefox exit, which prevents computer shutdown from GNOME

[Michael Mess]

The output of ps xHwl shows that the process seems to be ptraced.

0  1000 18727     1  20   0 252264 60284 futex_ Sl   ?          0:23 /usr/lib/firefox-3.6.24/firefox-bin
1  1000 18727     1  20   0 252264 60284 futex_ Sl   ?          0:00 /usr/lib/firefox-3.6.24/firefox-bin
1  1000 18727     1  20   0 252264 60284 futex_ Sl   ?          0:00 /usr/lib/firefox-3.6.24/firefox-bin
1  1000 18727     1  20   0 252264 60284 wait   Sl   ?          0:00 /usr/lib/firefox-3.6.24/firefox-bin
1  1000 18727     1  20   0 252264 60284 poll_s Sl   ?          0:00 /usr/lib/firefox-3.6.24/firefox-bin
0  1000 18768 18727  20   0 104156 18380 ptrace Tl   ?          0:00 /usr/lib/firefox-3.6.24/plugin-container /usr/lib/adobe-flashplugin/libflashplayer.so 18727 plugin true
1  1000 18768 18727  20   0 104156 18380 unix_s Sl   ?          0:02 /usr/lib/firefox-3.6.24/plugin-container /usr/lib/adobe-flashplugin/libflashplayer.so 18727 plugin true

This would explain, why strace could not connect. From the documentation
of the ptrace system call:

"EPERM
    The specified process cannot be traced. This could be because the parent has insufficient privileges (the required capability is CAP_SYS_PTRACE); unprivileged processes cannot trace processes that they cannot send signals to or those running set-user-ID/set-group-ID programs, for obvious reasons. Alternatively, the process may already be being traced, or be init(8) (PID 1). "

Does firefox make use of the ptrace system call to control its
subprocess?

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Title:
  /usr/lib/firefox-4.0/plugin-container hangs upon Firefox exit, which
  prevents computer shutdown from GNOME

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