From: Oleg Nesterov <oleg@redhat.com>
Date: Mon, 4 Feb 2013 16:48:34 +0000 (+0100)
Subject: uprobes/perf: Teach trace_uprobe/perf code to use UPROBE_HANDLER_REMOVE
X-Git-Tag: v3.9-rc1~173^2~2^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f42d24a1d20d2e72d1e5d48930f18b138dfad117;p=pandora-kernel.git

uprobes/perf: Teach trace_uprobe/perf code to use UPROBE_HANDLER_REMOVE

Change uprobe_trace_func() and uprobe_perf_func() to return "int". Change
uprobe_dispatcher() to return "trace_ret | perf_ret" although this is not
needed, currently TP_FLAG_TRACE/TP_FLAG_PROFILE are mutually exclusive.

The only functional change is that uprobe_perf_func() checks the filtering
too and returns UPROBE_HANDLER_REMOVE if nobody wants to trace current.

Testing:

	# perf probe -x /lib/libc.so.6 syscall

	# perf record -e probe_libc:syscall -i perl -e 'fork; syscall -1 for 1..10; wait'

	# perf report --show-total-period
		100.00%            10     perl  libc-2.8.so    [.] syscall

Before this patch:

	# cat /sys/kernel/debug/tracing/uprobe_profile
		/lib/libc.so.6 syscall				20

A child process doesn't have a counter, but still it hits this breakoint
"copied" by dup_mmap().

After the patch:

	# cat /sys/kernel/debug/tracing/uprobe_profile
		/lib/libc.so.6 syscall				11

The child process hits this int3 only once and does unapply_uprobe().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
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