On 3/20/24 18:09, Masami Hiramatsu (Google) wrote:
On Wed, 20 Mar 2024 14:18:44 +0000
Mark Rutland <mark.rutland@xxxxxxx> wrote:
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.
Looks good to me.
Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
I think this should be a fix because test task name can have ':'.
Fixes: eb50d0f250e9 ("selftests/ftrace: Choose target function for filter test from samples")
Cc: stable@xxxxxxxxxxxxxxx
Shuah, can you pick this as a fix?
Applied to linux-ksleftest fixes for next rc
thanks,
-- Shuah
