[Bug tapsets/13452] tapset/nd_syscalls.stp:# FIXME: doesn't handle sys_eventfd2()

dsmith at redhat dot com sourceware-bugzilla@sourceware.org
Wed Nov 30 16:54:00 GMT 2011


http://sourceware.org/bugzilla/show_bug.cgi?id=13452

David Smith <dsmith at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dsmith at redhat dot com
         Depends on|                            |11424

--- Comment #1 from David Smith <dsmith at redhat dot com> 2011-11-30 16:53:02 UTC ---
Here's a bit more from tapset/syscalls.stp:

----
# eventfd _____________________________________________________                 
# long sys_eventfd(unsigned int count)                                          
# SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags)                    
probe syscall.eventfd = kernel.function("sys_eventfd2").call !,                 
                        kernel.function("sys_eventfd").call ?                   
----

The reason why it is done this way is that in the kernel sys_eventfd is just a
wrapper around sys_eventfd2.  This way we ignore the sys_eventfd call, and only
catch the sys_eventfd2 call on kernels with sys_eventfd2.

Unfortunately, as bug #11424 notes, '!' (optional and sufficient) doesn't work
for kprobe.function probes.  So, the above logic will be difficult to duplicate
in tapset/nd_syscalls.stp.

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