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[Bug uprobes/6841] system-wide utrace syscall tracing script don't respond signal
- From: "mhiramat at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 17 Aug 2008 20:22:56 -0000
- Subject: [Bug uprobes/6841] system-wide utrace syscall tracing script don't respond signal
- References: <20080813164019.6841.mhiramat@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From mhiramat at redhat dot com 2008-08-17 20:22 -------
After deep investigation by stap, I found a strange behaviour of utrace.
At utrace_set_flags(), it calls quiesce() and set TIF_SIGPENDING flag to target
thread, but utrace doesn't wake it up. If the target is waiting signal at that
time(ex. sigwait), it fails to wakeup when a signal was sent because it already
has TIF_SIGPENDING (see __group_complete_signal() and wants_signal() in
kernel/signal.c).
I think utrace_set_flags()/quiesce() should not use TIF_SIGPENDING.
--
http://sourceware.org/bugzilla/show_bug.cgi?id=6841
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