From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4E5E338757F; Thu, 30 Apr 2026 20:01:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777579301; cv=none; b=qrXsRvM3JK+70mPE7MgkAQzA18WjwT2cYb4prg+VQFDrEt2JhHRqjMsGk3I145bwDtQIGS4C02KBA879+QCnw14ghBbaCKs8YrbaMbbh69kMCbUt4I6tJM2uYGNPXx9xZKX2ASermGu/Gkt0HMw9wS30SaCmHoRrTg444o6PjXQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777579301; c=relaxed/simple; bh=7oGY8yQZmZVqH7VogZXoTauvK3oFgVKItJcXm+ZnCu4=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=J2WexwCSz0j8RI1DawuFGb2b07tI5ocIiXiTBPv86ggrfR9DoeV/CmsPkucMmRwtqXm3jJRKIsiVRZ+2QoCqz+f2SRoIk1yRR6iMvFEkgDfQaPTj5evqg4oTmJO0ymbUOe4yDouteVyjktxcKc6wMaXSgly+Gq1tAu+4vmRRA0w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Received: from omf09.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 7799C140170; Thu, 30 Apr 2026 20:01:38 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf09.hostedemail.com (Postfix) with ESMTPA id 5D4412002A; Thu, 30 Apr 2026 20:01:36 +0000 (UTC) Date: Thu, 30 Apr 2026 16:01:34 -0400 From: Steven Rostedt To: David Carlier Cc: linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, peterz@infradead.org, vineeth@bitbyteword.org Subject: Re: [PATCH v2] tracepoint: add lockdep rcu_is_watching() check to trace_##name##_enabled() Message-ID: <20260430160134.2964130a@gandalf.local.home> In-Reply-To: <20260430144159.10985-1-devnexen@gmail.com> References: <20260430053511.8767-1-devnexen@gmail.com> <20260430144159.10985-1-devnexen@gmail.com> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 44bijysaxrc4cb9k5jmnencubwenb8os X-Rspamd-Server: rspamout08 X-Rspamd-Queue-Id: 5D4412002A X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX19FvYrAG7ZUJ3Jezkz5hCVnYWn1NtdQ9Eo= X-HE-Tag: 1777579296-131249 X-HE-Meta: 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 On Thu, 30 Apr 2026 15:41:59 +0100 David Carlier wrote: > trace_call__##name() was added by commit 677a3d82b640 ("tracepoint: Add > trace_call__##name() API") for callers that already gate on > trace_##name##_enabled(), letting them skip the redundant > static_branch_unlikely() re-evaluation. The LOCKDEP rcu_is_watching() > WARN_ONCE() that trace_##name() carries on the disabled path was not > mirrored, so the cold-path coverage added by commit c2679254b9c9 > ("tracing: Make tracepoint lockdep check actually test something") is > lost for trace_call__##name() callers when the tracepoint is disabled. > > When the tracepoint is enabled, the rcu_dereference inside > __DO_TRACE_CALL() already trips under PROVE_RCU, so the warning is > only needed on the !enabled path. The natural place is the gate that > trace_call__##name() callers consult: trace_##name##_enabled(). > > Fixes: 677a3d82b640 ("tracepoint: Add trace_call__##name() API") Thanks, but I'm 86'ing the Fixes tag. The above commit has absolutely nothing to do with this patch. This issue was there from the beginning of having the trace_*_enabled() macro. This isn't a fix. I'll modify the change log to be more accurate as well. -- Steve > Cc: Vineeth Pillai (Google) > Cc: Mathieu Desnoyers > Cc: Masami Hiramatsu > Cc: Peter Zijlstra > Signed-off-by: David Carlier > --- > include/linux/tracepoint.h | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h > index 578e520b6ee6..3b3ab19c2627 100644 > --- a/include/linux/tracepoint.h > +++ b/include/linux/tracepoint.h > @@ -293,6 +293,10 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) > static inline bool \ > trace_##name##_enabled(void) \ > { \ > + if (IS_ENABLED(CONFIG_LOCKDEP)) { \ > + WARN_ONCE(!rcu_is_watching(), \ > + "RCU not watching for tracepoint"); \ > + } \ > return static_branch_unlikely(&__tracepoint_##name.key);\ > } >