linux-kernel - Re: [PATCH PATCH 2/2] selftests: livepatch: test if ftrace can trace a livepatched function

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Message-ID: <alpine.LSU.2.21.2503141411010.4442@pobox.suse.cz>
Date: Fri, 14 Mar 2025 14:14:47 +0100 (CET)
From: Miroslav Benes <mbenes@...e.cz>
To: Filipe Xavier <felipeaggger@...il.com>
cc: Josh Poimboeuf <jpoimboe@...nel.org>, Jiri Kosina <jikos@...nel.org>, 
    Petr Mladek <pmladek@...e.com>, Joe Lawrence <joe.lawrence@...hat.com>, 
    Shuah Khan <shuah@...nel.org>, Marcos Paulo de Souza <mpdesouza@...e.com>, 
    live-patching@...r.kernel.org, linux-kselftest@...r.kernel.org, 
    linux-kernel@...r.kernel.org, felipe_life@...e.com
Subject: Re: [PATCH PATCH 2/2] selftests: livepatch: test if ftrace can trace
 a livepatched function

Hi,

> +start_test "trace livepatched function and check that the live patch remains in effect"
> +
> +FUNCTION_NAME="livepatch_cmdline_proc_show"
> +
> +load_lp $MOD_LIVEPATCH
> +trace_function "$FUNCTION_NAME"

trace_funtion() calls cleanup_ftrace() to prepare the test. Ok.

> +if [[ "$(cat /proc/cmdline)" == "$MOD_LIVEPATCH: this has been live patched" ]] ; then
> +	log "livepatch: ok"
> +fi
> +
> +check_traced_function "$FUNCTION_NAME"
> +
> +cleanup_tracing

Here, I suppose, cleanup_tracing() is called to clean up after the check 
above so that nothing stays and more tests can be added later. Right? 
Would it make sense then to call cleanup_tracing() in 
check_traced_function()? I think it would less error prone. 
If needed, check_traced_function() can always be upgraded so that it 
checks for more traced functions.

Miroslav