WARN_ONCE() splats once per call site, so only the first offending event
registered is ever reported. The tree currently has six:
ice_{rx,tx}_dim_template, two hfi1 txq events, mtu3_ep and edma_log_io.
Whichever registers first hides the rest, and each has to be found again
on the next boot.

Add a pr_warn() next to the WARN_ONCE() so every offender is listed, the
same way test_event_printk() already pairs WARN_ON_ONCE() with pr_warn()
for unsafe %p* dereferences. The WARN_ONCE() stays so the condition still
fails tests and panics under panic_on_warn.

Suggested-by: Steven Rostedt <[email protected]>
Signed-off-by: David Carlier <[email protected]>
---
 kernel/trace/trace_events.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index a8590d2394e3..ce902482ec7c 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -415,6 +415,8 @@ static void test_double_dereference(const char *str, int 
len,
                ptr += 5;
                for (; ptr < end; ptr++) {
                        if (ptr[0] == '-' && ptr[1] == '>') {
+                               pr_warn("TRACE EVENT ERROR: Event %s has double 
dereference in TP_printk: %.*s\n",
+                                       trace_event_name(call), len, str);
                                WARN_ONCE(1, "Event %s has double dereference 
in TP_printk: %.*s\n",
                                          trace_event_name(call), len, str);
                                return;
-- 
2.55.0


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