On 20-Oct-2022, at 8:10 PM, Peter Zijlstra [off-list ref] wrote:

On Thu, Oct 20, 2022 at 12:36:56PM +0530, Athira Rajeev wrote:

quoted

commit 838d9bb62d13 ("perf: Use sample_flags for raw_data")
added check for PERF_SAMPLE_RAW in sample_flags in
perf_prepare_sample(). But while copying the sample in memory,
the check for sample_flags is not added in perf_output_sample().
Fix adds the same in perf_output_sample as well.

Fixes: 838d9bb62d13 ("perf: Use sample_flags for raw_data")
Signed-off-by: Athira Rajeev <redacted>
---
kernel/events/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 4ec3717003d5..daf387c75d33 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c

@@ -7099,7 +7099,7 @@ void perf_output_sample(struct perf_output_handle *handle,

	if (sample_type & PERF_SAMPLE_RAW) {
		struct perf_raw_record *raw = data->raw;

-		if (raw) {
+		if (raw && (data->sample_flags & PERF_SAMPLE_RAW)) {
			struct perf_raw_frag *frag = &raw->frag;

			perf_output_put(handle, raw->size);

Urgh.. something smells here. We already did a PERF_SAMPLE_RAW test.

And perf_prepare_sample() explicitly makes data->raw be NULL when not
set earlier.

So what's going wrong?

Hi Peter,

Sorry for late response. I was out on vacation couple of days.

I didn't hit any specific issue or fail with current code. But patch intention was
to keep the perf_prepare_sample and perf_output_sample to be in sync with the checks that we
are doing.

Thanks
Athira