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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4995420cb4esm32477045e9.2.2026.08.05.22.07.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Aug 2026 22:07:19 -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] tracing: Report TP_printk double dereference with pr_warn() Date: Thu, 6 Aug 2026 06:07:16 +0100 Message-ID: <20260806050716.16612-1-devnexen@gmail.com> X-Mailer: git-send-email 2.55.0 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 test_double_dereference() uses WARN_ONCE(), which is per-call-site. Only the first offending event in the kernel is ever reported, and the tree still has six: ice_{rx,tx}_dim_template, two hfi1 txq events, mtu3_ep and edma_log_io. Whichever registers first hides the rest, and it taints the kernel for what is a source-level mistake. Use pr_warn() instead, matching the "TRACE EVENT ERROR:" report that handle_dereference_arg() already emits for the same class of problem. All offenders are now listed on one boot. Fixes: b5cc230af5e5 ("tracing: Warn when an event dereferences a pointer in TP_printk()") Signed-off-by: David Carlier --- kernel/trace/trace_events.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index a8590d2394e3..53f32752edc0 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -415,8 +415,8 @@ static void test_double_dereference(const char *str, int len, ptr += 5; for (; ptr < end; ptr++) { if (ptr[0] == '-' && ptr[1] == '>') { - WARN_ONCE(1, "Event %s has double dereference in TP_printk: %.*s\n", - trace_event_name(call), len, str); + pr_warn("TRACE EVENT ERROR: Event %s has double dereference in TP_printk: %.*s\n", + trace_event_name(call), len, str); return; } if (!isalnum(*ptr) && *ptr != '_') -- 2.55.0