Re: [PATCH 2/2] check: generate gcov code coverage reports at the end of each section

[Zorro Lang <zlang@redhat.com>]

On Tue, Jul 18, 2023 at 06:11:01PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Support collecting kernel code coverage information as reported in
> debugfs.  At the start of each section, we reset the gcov counters;
> during the section wrapup, we'll collect the kernel gcov data.
> 
> If lcov is installed and the kernel source code is available, it will
> also generate a nice html report.  If a CLI web browser is available, it
> will also format the html report into text for easy grepping.
> 
> This requires the test runner to set REPORT_GCOV=1 explicitly and gcov
> to be enabled in the kernel.
> 
> Cc: tytso@mit.edu
> Cc: kent.overstreet@linux.dev
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---

Hi Darrick,

Is that possible to split this function from check script to tools/ ?

Thanks,
Zorro

>  README |    3 ++
>  check  |   86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 89 insertions(+)
> 
> 
> diff --git a/README b/README
> index 9790334db1..ccfdcbe703 100644
> --- a/README
> +++ b/README
> @@ -249,6 +249,9 @@ Kernel/Modules related configuration:
>     to "forever" and we'll wait forever until the module is gone.
>   - Set KCONFIG_PATH to specify your preferred location of kernel config
>     file. The config is used by tests to check if kernel feature is enabled.
> + - Set REPORT_GCOV to a directory path to make lcov and genhtml generate
> +   html reports from any gcov code coverage data collected by the kernel.
> +   If REPORT_GCOV is set to 1, the report will be written to $REPORT_DIR/gcov/.
>  
>  Test control:
>   - Set LOAD_FACTOR to a nonzero positive integer to increase the amount of
> diff --git a/check b/check
> index 97c7c4c7d1..3e6f27c653 100755
> --- a/check
> +++ b/check
> @@ -451,6 +451,87 @@ _global_log() {
>  	fi
>  }
>  
> +GCOV_DIR=/sys/kernel/debug/gcov
> +
> +# Find the topmost directories of the .gcno directory hierarchy
> +_gcov_find_topdirs() {
> +	find "${GCOV_DIR}/" -name '*.gcno' -printf '%d|%h\n' | \
> +		sort -g -k 1 | \
> +		uniq | \
> +		$AWK_PROG -F '|' 'BEGIN { x = -1 } { if (x < 0) x = $1; if ($1 == x) printf("%s\n", $2);}'
> +}
> +
> +# Generate lcov html report from kernel gcov data if configured
> +_gcov_generate_report() {
> +	unset REPORT_GCOV	# don't trigger multiple times if ^C
> +
> +	local output_dir="$1"
> +	test -n "${output_dir}" || return
> +	test "$output_dir" = "1" && output_dir="$REPORT_DIR/gcov"
> +
> +	# Kernel support built in?
> +	test -d "$GCOV_DIR" || return
> +
> +	readarray -t gcno_dirs < <(_gcov_find_topdirs)
> +	test "${#gcno_dirs[@]}" -gt 0 || return
> +
> +	mkdir -p "${output_dir}/"
> +
> +	# Collect raw coverage data from the kernel
> +	readarray -t source_dirs < <(find "${GCOV_DIR}/" -mindepth 1 -maxdepth 1 -type d)
> +	for dir in "${source_dirs[@]}"; do
> +		cp -p -R -d -u "${dir}" "${output_dir}/"
> +	done
> +
> +	# If lcov is installed, use it to summarize the gcda data.
> +	# If it is not installed, there's no point in going forward
> +	command -v lcov > /dev/null || return
> +	local lcov=(lcov --exclude 'include*' --capture)
> +	lcov+=(--output-file "${output_dir}/gcov.report")
> +	for d in "${gcno_dirs[@]}"; do
> +		lcov+=(--directory "${d}")
> +	done
> +
> +	# Generate a detailed HTML report from the summary
> +	local gcov_start_time="$(date --date="${fstests_start_time:-now}")"
> +	local genhtml=()
> +	if command -v genhtml > /dev/null; then
> +		genhtml+=(genhtml -o "${output_dir}/" "${output_dir}/gcov.report")
> +		genhtml+=(--title "fstests on $(hostname -s) @ ${gcov_start_time}" --legend)
> +	fi
> +
> +	# Try to convert the HTML report summary as text for easier grepping if
> +	# there's an HTML renderer present
> +	local totext=()
> +	test "${#totext[@]}" -eq 0 && \
> +		command -v lynx &>/dev/null && \
> +		totext=(lynx -dump "${output_dir}/index.html" -width 120 -nonumbers -nolist)
> +	test "${#totext[@]}" -eq 0 && \
> +		command -v links &>/dev/null && \
> +		totext=(links -dump "${output_dir}/index.html" -width 120)
> +	test "${#totext[@]}" -eq 0 && \
> +		command -v elinks &>/dev/null && \
> +		totext=(elinks -dump "${output_dir}/index.html" --dump-width 120 --no-numbering --no-references)
> +
> +	# Analyze kernel data
> +	"${lcov[@]}" > "${output_dir}/gcov.stdout" 2> "${output_dir}/gcov.stderr"
> +	test "${#genhtml[@]}" -ne 0 && \
> +		"${genhtml[@]}" >> "${output_dir}/gcov.stdout" 2>> "${output_dir}/gcov.stderr"
> +	test "${#totext[@]}" -ne 0 && \
> +		"${totext[@]}" > "${output_dir}/index.txt" 2>> "${output_dir}/gcov.stderr"
> +}
> +
> +# Reset gcov usage data
> +_gcov_reset() {
> +	test -n "${REPORT_GCOV}" || return
> +
> +	if [ -w "${GCOV_DIR}/reset" ]; then
> +		echo 1 > "${GCOV_DIR}/reset"
> +	else
> +		unset REPORT_GCOV
> +	fi
> +}
> +
>  _wrapup()
>  {
>  	seq="check"
> @@ -527,6 +608,10 @@ _wrapup()
>  					     "${#bad[*]}" "${#notrun[*]}" \
>  					     "$((sect_stop - sect_start))"
>  		fi
> +
> +		# Generate code coverage report
> +		test -n "$REPORT_GCOV" && _gcov_generate_report "$REPORT_GCOV"
> +
>  		needwrap=false
>  	fi
>  
> @@ -801,6 +886,7 @@ function run_section()
>  	  echo "MOUNT_OPTIONS -- `_scratch_mount_options`"
>  	fi
>  	echo
> +	_gcov_reset
>  	needwrap=true
>  
>  	if [ ! -z "$SCRATCH_DEV" ]; then
>