Re: [PATCH v1 2/5] perf test trace: Remove set -e and print trace test's error messages

[Namhyung Kim <namhyung@kernel.org>]

Hi Howard,

On Sat, May 17, 2025 at 09:32:27AM -0700, Howard Chu wrote:
> Currently perf test utilizes the set -e option in shell that exit
> immediately if a command exits with a non-zero status, this prevents
> further error handling and introduces ambiguity. This patch removes set
> -e and prints the error message after invoking perf trace during perf
> tests.

I think it's fine to exits with non-zero inside 'if' statements.  But
it won't work if you want to move it out of the 'if' statements.  I'm
not sure how it'd work in a subshll for the assignment.  But it'd be ok
to remove 'set -e' anyway since the test checks the result manually.

Thanks,
Namhyung

> 
> In my case, the command that exits with a non-zero status is perf
> trace instead of grep, because it can't find the 'timer:hrtimer_setup'
> tracepoint, see below.
> 
> Before:
>     $ sudo /tmp/perf test enum -vv
>     107: perf trace enum augmentation tests:
>     107: perf trace enum augmentation tests                              : Running
>     --- start ---
>     test child forked, pid 783533
>     Checking if vmlinux exists
>     Tracing syscall landlock_add_rule
>     Tracing non-syscall tracepoint syscall
>     ---- end(-1) ----
>     107: perf trace enum augmentation tests                              : FAILED!
> 
> After:
>     $ sudo /tmp/perf test enum -vv
>     107: perf trace enum augmentation tests:
>     107: perf trace enum augmentation tests                              : Running
>     --- start ---
>     test child forked, pid 851658
>     Checking if vmlinux exists
>     Tracing syscall landlock_add_rule
>     Tracing non-syscall tracepoint timer:hrtimer_setup,timer:hrtimer_start
>     [tracepoint failure] Failed to trace tracepoint timer:hrtimer_setup,timer:hrtimer_start, output:
>     event syntax error: 'timer:hrtimer_setup,timer:hrtimer_start'
> 			 \___ unknown tracepoint
> 
>     Error:  File /sys/kernel/tracing//events/timer/hrtimer_setup not found.
>     Hint:   Perhaps this kernel misses some CONFIG_ setting to enable this feature?.
> 
>     Run 'perf list' for a list of valid events
> 
>      Usage: perf trace [<options>] [<command>]
> 	or: perf trace [<options>] -- <command> [<options>]
> 	or: perf trace record [<options>] [<command>]
> 	or: perf trace record [<options>] -- <command> [<options>]
> 
> 	-e, --event <event>   event/syscall selector. use 'perf list' to list available events---- end(-1) ----
>     107: perf trace enum augmentation tests                              : FAILED!
> 
> Signed-off-by: Howard Chu <howardchu95@gmail.com>
> ---
>  tools/perf/tests/shell/trace_btf_enum.sh | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/tests/shell/trace_btf_enum.sh b/tools/perf/tests/shell/trace_btf_enum.sh
> index b3775209a0b1..cd4c8754f5d4 100755
> --- a/tools/perf/tests/shell/trace_btf_enum.sh
> +++ b/tools/perf/tests/shell/trace_btf_enum.sh
> @@ -3,7 +3,6 @@
>  # SPDX-License-Identifier: GPL-2.0
>  
>  err=0
> -set -e
>  
>  syscall="landlock_add_rule"
>  non_syscall="timer:hrtimer_setup,timer:hrtimer_start"
> @@ -34,22 +33,24 @@ trace_landlock() {
>      return
>    fi
>  
> -  if perf trace -e $syscall $TESTPROG 2>&1 | \
> -     grep -q -E ".*landlock_add_rule\(ruleset_fd: 11, rule_type: (LANDLOCK_RULE_PATH_BENEATH|LANDLOCK_RULE_NET_PORT), rule_attr: 0x[a-f0-9]+, flags: 45\) = -1.*"
> +  output="$(perf trace -e $syscall $TESTPROG 2>&1)"
> +  if echo "$output" | grep -q -E ".*landlock_add_rule\(ruleset_fd: 11, rule_type: (LANDLOCK_RULE_PATH_BENEATH|LANDLOCK_RULE_NET_PORT), rule_attr: 0x[a-f0-9]+, flags: 45\) = -1.*"
>    then
>      err=0
>    else
> +	printf "[syscall failure] Failed to trace syscall $syscall, output:\n$output"
>      err=1
>    fi
>  }
>  
>  trace_non_syscall() {
> -  echo "Tracing non-syscall tracepoint ${non-syscall}"
> -  if perf trace -e $non_syscall --max-events=1 2>&1 | \
> -     grep -q -E '.*timer:hrtimer_.*\(.*mode: HRTIMER_MODE_.*\)$'
> +  echo "Tracing non-syscall tracepoint ${non_syscall}"
> +  output="$(perf trace -e $non_syscall --max-events=1 2>&1)"
> +  if echo "$output" | grep -q -E '.*timer:hrtimer_.*\(.*mode: HRTIMER_MODE_.*\)$'
>    then
>      err=0
>    else
> +	printf "[tracepoint failure] Failed to trace tracepoint $non_syscall, output:\n$output"
>      err=1
>    fi
>  }
> -- 
> 2.45.2
>