Messages in this thread | | | Date | Thu, 11 Nov 2004 12:45:12 -0500 | From | Daniel Jacobowitz <> | Subject | Re: Fixing UML against NPTL (was: Re: [uml-devel] [PATCH] UML: Use PTRACE_KILL instead of SIGKILL to kill host-OS processes (take #2)) |
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On Thu, Nov 04, 2004 at 05:31:21AM +0100, Blaisorblade wrote: > 2) getpid() on a child clone returns the process's pid when run with a > NPTL-enabled glibc, while it returns the thread pid with a LinuxThreads one; > this causes tons of problems with UML, which uses signals as inter-thread and > intra-thread communication. > > Note UML is not using pthread_create() to create the threads, where this > behaviour is an improvement. I'm using a plain clone() call without the > CLONE_THREAD flag (which is not even added in by glibc, according to strace). > > I've not yet checked if glibc is hijacking getpid() or not, but that would be > strange anyway.
Glibc caches the PID. If you're going to use clone directly, use the gettid/getpid syscall directly. It's kind of rude that glibc breaks getpid in this way; I recommend filing a bug in the glibc bugzilla at sources.redhat.com.
-- Daniel Jacobowitz - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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