[Bug kprobes/1971] New: Unregister race in RCU kprobes

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[Bug kprobes/1971] New: Unregister race in RCU kprobes

fweimer at redhat dot com
When registering a second kprobe at the same address as the first kprobe
(Multiple kprobes at the same address), add_aggr_kprobe() gets called. In
add_aggr_kprobe() we delete the first kprobe element from the *hash list* and
add the aggregate kprobe structure to the hash list(the first kprobe structure
is linked to aggregate kprobe)
During this process of swapping, their is a small window in which their is
*no* associated kprobe for that particular address.

If during this small window, if other cpu in kprobe_handler() code, calls
get_kprobe() for that particular address, then get_kprobe() returns null and
their by we handle our probe incorrectly leading the system to crash.

--
           Summary: Unregister race in RCU kprobes
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: kprobes
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: anil dot s dot keshavamurthy at intel dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=1971

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[Bug kprobes/1971] Register race in RCU kprobes

fweimer at redhat dot com


--
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Unregister race in RCU      |Register race in RCU kprobes
                   |kprobes                     |


http://sourceware.org/bugzilla/show_bug.cgi?id=1971

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[Bug kprobes/1971] Register race in RCU kprobes

fweimer at redhat dot com
In reply to this post by fweimer at redhat dot com

------- Additional Comments From varap at us dot ibm dot com  2005-12-02 23:30 -------
Ananth can you look into this bug.


--
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |prasanna at in dot ibm dot
                   |                            |com, jkenisto at us dot ibm
                   |                            |dot com
         AssignedTo|systemtap at sources dot    |amavin at redhat dot com
                   |redhat dot com              |
             Status|NEW                         |ASSIGNED


http://sourceware.org/bugzilla/show_bug.cgi?id=1971

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