From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D74042D46CA; Sat, 16 Aug 2025 14:50:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755355830; cv=none; b=YlGqqhWIPi2YbWMPj43H4KBPW2+UbRz+P2LLXu1MYj4m1MmgZCanIW4rZDVg/oENyekpKweIHkaYYaOsv6e6/pBs1YLj25EFUBp/Qo2hxD0sDGHOYbw9C2X1noZuUrmJqolLfCWaHd4hzw2g4vpYvXZO00eYYgEBlRbr7LKx35g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755355830; c=relaxed/simple; bh=3/6j6G8m0fiGcHsJh9fJn6cHi5TaoU26V0jjDuRfG+A=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=VsMtu4UU4/DgQAtRIrBVD/Nlak/KGlIWlAhLR9C6tV4ud0mLsfdv2JLBzbIyFO/XMG5pp4tlMIWCBSvC7v8ozL7oK3GsIKq1YGzseYVceZIGRmjLm3mBYfmZackjLtR7ZZf6Eg9WVSsRu+wgEJMdmYZHB6QU/qo1vWU40+v2s64= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f5cR47R6; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="f5cR47R6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1AA1CC4CEEF; Sat, 16 Aug 2025 14:50:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755355829; bh=3/6j6G8m0fiGcHsJh9fJn6cHi5TaoU26V0jjDuRfG+A=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=f5cR47R6qxae48z9hM2mG0DES2xjsZfWd4eXtRf/u1POszbsgvpHz4oYwRrRBX+sF HG6wQSXjA+J2Q+ejd2Hjw0bdXH/x8EWJdO1fFoHk7HM+xI8vmqM62WFKbmytnFv2gr HeVNXOvdO5WWPv5M0aSm6ulo7kGtnqi6KPVSSUZtlC/XrI0kijHEBDuR8aqk5NX/sG VkDKCpTG3iO7R0NcddX+8jEUIjsKu/eC+JsuYcF0W4VMqramGQmI/6qiHiQAGxZfJh z4ttB6PpFLctgPaTtIZLTJ3gwcR7uCGS71IV8U8gBMYH3xtEPGVFJlnj1bIwegDXO+ SSLSAs0zDe72A== Date: Sat, 16 Aug 2025 23:50:23 +0900 From: Masami Hiramatsu (Google) To: Menglong Dong Cc: olsajiri@gmail.com, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, hca@linux.ibm.com, revest@chromium.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH bpf-next v4 1/4] fprobe: use rhltable for fprobe_ip_table Message-Id: <20250816235023.4dabfbc13a46a859de61cf4d@kernel.org> In-Reply-To: <20250815064712.771089-2-dongml2@chinatelecom.cn> References: <20250815064712.771089-1-dongml2@chinatelecom.cn> <20250815064712.771089-2-dongml2@chinatelecom.cn> X-Mailer: Sylpheed 3.8.0beta1 (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 Hi Menglong, Sorry, one more thing. > @@ -260,14 +263,12 @@ static int fprobe_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops, > if (WARN_ON_ONCE(!fregs)) > return 0; > > - first = node = find_first_fprobe_node(func); > - if (unlikely(!first)) > - return 0; > - > + rcu_read_lock(); Actually, we don't need these rcu_read_lock() in this function, because the caller function_graph_enter_regs() uses ftrace_test_recursion_trylock() which disables preemption. Thus we don't need to do this again here. > + head = rhltable_lookup(&fprobe_ip_table, &func, fprobe_rht_params); > reserved_words = 0; > - hlist_for_each_entry_from_rcu(node, hlist) { > + rhl_for_each_entry_rcu(node, pos, head, hlist) { > if (node->addr != func) > - break; > + continue; > fp = READ_ONCE(node->fp); > if (!fp || !fp->exit_handler) > continue; > @@ -278,17 +279,19 @@ static int fprobe_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops, > reserved_words += > FPROBE_HEADER_SIZE_IN_LONG + SIZE_IN_LONG(fp->entry_data_size); > } > - node = first; > + rcu_read_unlock(); > if (reserved_words) { > fgraph_data = fgraph_reserve_data(gops->idx, reserved_words * sizeof(long)); > if (unlikely(!fgraph_data)) { > - hlist_for_each_entry_from_rcu(node, hlist) { > + rcu_read_lock(); Ditto. > + rhl_for_each_entry_rcu(node, pos, head, hlist) { > if (node->addr != func) > - break; > + continue; > fp = READ_ONCE(node->fp); > if (fp && !fprobe_disabled(fp)) > fp->nmissed++; > } > + rcu_read_unlock(); > return 0; > } > } Thank you, -- Masami Hiramatsu (Google)