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Re: Listing probe alias resolution failures
Frank Ch. Eigler wrote:
Hi -
[...]
Ah, I see something I missed before with the following:
# stap -p2 -e 'probe vm.mmap ? { printf("%p %d\n", address, length) }'
[...]
probe vm.mmap = kernel.function("do_mmap"), kernel.function("do_mmap2")? {
address = $addr
length = $len
}
[...]
I missed the fact that the first one isn't optional. But, shouldn't
making 'vm.mmap' optional basically make 'kernel.function("do_mmap")'
optional?
But "do_mmap" is found, and so the optional flag is satisfied. The
probe handler is processed without further error suppression. It's
not obvious that this is wrong.
I guess I was thinking that the "optionalness" of vm.mmap would have
meant that when do_mmap wasn't found, vm.mmap would be tossed (so that
there would be no attempt to look up $addr and $len)
Perhaps the real bug is that the kernel.function("do_mmap") should be
made optional in the vm.mmap probe alias.
--
David Smith
dsmith@redhat.com
Red Hat
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