The event filter function test has been failing in our internal test farm:
| # not ok 33 event filter function - test event filtering on functions
Running the test in verbose mode indicates that this is because the test erroneously determines that kmem_cache_free() is the most common caller of kmem_cache_free():
# # + cut -d: -f3 trace # # + sed s/call_site=([^+]*)+0x.*/1/ # # + sort # # + uniq -c # # + sort # # + tail -n 1 # # + sed s/^[ 0-9]*// # # + target_func=kmem_cache_free
... and as kmem_cache_free() doesn't call itself, setting this as the filter function for kmem_cache_free() results in no hits, and consequently the test fails:
# # + grep kmem_cache_free trace # # + grep kmem_cache_free # # + wc -l # # + hitcnt=0 # # + grep kmem_cache_free trace # # + grep -v kmem_cache_free # # + wc -l # # + misscnt=0 # # + [ 0 -eq 0 ] # # + exit_fail
This seems to be because the system in question has tasks with ':' in their name (which a number of kernel worker threads have). These show up in the trace, e.g.
test:.sh-1299 [004] ..... 2886.040608: kmem_cache_free: call_site=putname+0xa4/0xc8 ptr=000000000f4d22f4 name=names_cache
... and so when we try to extact the call_site with:
cut -d: -f3 trace | sed 's/call_site=([^+]*)+0x.*/\1/'
... the 'cut' command will extrace the column containing 'kmem_cache_free' rather than the column containing 'call_site=...', and the 'sed' command will leave this unchanged. Consequently, the test will decide to use 'kmem_cache_free' as the filter function, resulting in the failure seen above.
Fix this by matching the 'call_site=<func>' part specifically to extract the function name.
Signed-off-by: Mark Rutland mark.rutland@arm.com Reported-by: Aishwarya TCV aishwarya.tcv@arm.com Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Mathieu Desnoyers mathieu.desnoyers@efficios.com Cc: Shuah Khan shuah@kernel.org Cc: Steven Rostedt rostedt@goodmis.org Cc: linux-kernel@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Cc: linux-trace-kernel@vger.kernel.org --- .../selftests/ftrace/test.d/filter/event-filter-function.tc | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc b/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc index 2de7c61d1ae3..3f74c09c56b6 100644 --- a/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc +++ b/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc @@ -24,7 +24,7 @@ echo 0 > events/enable echo "Get the most frequently calling function" sample_events
-target_func=`cut -d: -f3 trace | sed 's/call_site=([^+]*)+0x.*/\1/' | sort | uniq -c | sort | tail -n 1 | sed 's/^[ 0-9]*//'` +target_func=`cat trace | grep -o 'call_site=([^+]*)' | sed 's/call_site=//' | sort | uniq -c | sort | tail -n 1 | sed 's/^[ 0-9]*//'` if [ -z "$target_func" ]; then exit_fail fi