From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from abb.hmeau.com (abb.hmeau.com [180.181.231.80]) (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 131CB242D98; Tue, 2 Sep 2025 09:17:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=180.181.231.80 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756804642; cv=none; b=qCVhHrhfIF2A5hHXoTveX3ZrvR/giB3HZYXraairoz4rdj+vK9a7rYegfhwjygqwVkvHkcXTD6N2haAM886xdy34dLoOC2OF2NkmVqujlmiNMcKORa2kZj9oOnzJ5QMxerVzliJ4EDmaneRYUJ+jJO+7AeiQvrwsVT13KG5/2z8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756804642; c=relaxed/simple; bh=u/gpzFc54E7Qkui3Rf+FQee8DH7Jl2fl0v2tnQNBejs=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=mI+bIWXjt7zO6tA2VqT13z3xa5cXNCQOOyNQu+qIiWZdgNo+/PcQKx45e8LMjPZCzGcpzzO7JoT7l+UH860qPJ4gDHNCoK172+3+Y1si6eFLzWsYupn+EiL/Lwy7bpbFIPHwTKH4QBlyy1VCYVBCvhiIBtFWjeBrmm2737UgxVE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gondor.apana.org.au; spf=pass smtp.mailfrom=gondor.apana.org.au; dkim=pass (2048-bit key) header.d=hmeau.com header.i=@hmeau.com header.b=kWNUjHso; arc=none smtp.client-ip=180.181.231.80 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gondor.apana.org.au Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gondor.apana.org.au Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=hmeau.com header.i=@hmeau.com header.b="kWNUjHso" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=hmeau.com; s=formenos; h=In-Reply-To:Content-Type:MIME-Version:Message-ID:Subject:Cc:To: From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=2Dmf2HsAjLA9aMcC0oK5XbhwP0WeOH0TUSdhNSFuoWg=; b=kWNUjHso6SRKfHUaQV0X1yfbm0 fdGdpbbUrng21bwO4DHcKE2NjzYFD0RDzw4CYke6Y7od3AKYiCJthROr7U4SJkJm8KO7SPw3QfAwy 1WRWtJ8MiKS94qm0OZIF7kF4sVAH7tfiEAITMJ7SU1PuVQ2rDsTJNdicyvlUxnGyyAWSl6r1arbPS n/bbJQiCpmCWbrH42wGlDI+OuKy3n/izvdnSXHmhdoPVNo7Vj3h7oh4H0ZHbp23BSnD02t1ONd/zY URPWEI8rmJdSoqwskcX7uV2VMMCOTqC7rqtbXrSLdlvTzyq7VsZuD02gFcyJyazBEZNR/OYHrGjgM tPICuk9g==; Received: from loth.rohan.me.apana.org.au ([192.168.167.2]) by formenos.hmeau.com with smtp (Exim 4.96 #2 (Debian)) id 1utMt1-001wj9-1v; Tue, 02 Sep 2025 17:17:05 +0800 Received: by loth.rohan.me.apana.org.au (sSMTP sendmail emulation); Tue, 02 Sep 2025 17:17:03 +0800 Date: Tue, 2 Sep 2025 17:17:03 +0800 From: Herbert Xu To: Menglong Dong Cc: mhiramat@kernel.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, oliver.sang@intel.com Subject: Re: [PATCH] tracing: fprobe: fix suspicious rcu usage in fprobe_entry Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250829021436.19982-1-dongml2@chinatelecom.cn> X-Newsgroups: apana.lists.os.linux.kernel Menglong Dong wrote: > > diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c > index fb127fa95f21..fece0f849c1c 100644 > --- a/kernel/trace/fprobe.c > +++ b/kernel/trace/fprobe.c > @@ -269,7 +269,9 @@ static int fprobe_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops, > if (WARN_ON_ONCE(!fregs)) > return 0; > > + rcu_read_lock(); > head = rhltable_lookup(&fprobe_ip_table, &func, fprobe_rht_params); > + rcu_read_unlock(); > reserved_words = 0; > rhl_for_each_entry_rcu(node, pos, head, hlist) { > if (node->addr != func) Actually this isn't quite right. I know that it is a false-positive so that it's actually safe, but if you're going to mark it with rcu_read_lock, it should cover both the lookup as well as the dereference which happens in the loop rhl_for_each_entry_rcu. Thanks, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt