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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-499541b86f5sm91381405e9.0.2026.08.06.14.52.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Aug 2026 14:52:59 -0700 (PDT) From: David Carlier To: Steven Rostedt Cc: Masami Hiramatsu , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, David Carlier Subject: [PATCH v2] tracing: Report every TP_printk double dereference Date: Thu, 6 Aug 2026 22:52:56 +0100 Message-ID: <20260806215256.1680267-1-devnexen@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260806174110.11fcd317@gandalf.local.home> References: <20260806174110.11fcd317@gandalf.local.home> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 Signed-off-by: David Carlier --- 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