From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) (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 0668E1DF980; Tue, 24 Mar 2026 12:38:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774355907; cv=none; b=EpWTu7Hujal8se7l7Xg0OpRno9803qvQDAQeO4ODJ7MtsBjqWRagbz3V1FtLQeZiJEg80XLtXgNJ4RRI+mb2/IjuDmbzwQAJiquruLTypXj5dKGFHUfKCH9Qp+vJuy6g6+z4MAw7Pm2noRLU3WOrFO4X6h7ZUZkvvSHTtGjXjzY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774355907; c=relaxed/simple; bh=6SI9y8m/OHmwOY4jJ91uhi4+UdGQdJyw4oq2Ofh+hM0=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=bMOZGSExeYr9m0vlkvqHICZmr2QT85sehlaXx7R+k5ExqjKXMFG42/nBrGIMLhrnKVJAixHd6hyGDK5DaNhG/nYnFXS5CV3OIJsfhbrW+kn4EbtXlaLd8+9u4Aj/P1dkEQMS2E4KZwrBIjlKWDv3pAa5HinpRqzUY0alsCyEi1c= 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=216.40.44.16 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 omf17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 940FEBA44E; Tue, 24 Mar 2026 12:38:24 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf17.hostedemail.com (Postfix) with ESMTPA id D155117; Tue, 24 Mar 2026 12:38:22 +0000 (UTC) Date: Tue, 24 Mar 2026 08:39:03 -0400 From: Steven Rostedt To: Martin Kaiser Cc: Masami Hiramatsu , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] tracing: fprobe: do not zero out unused fgraph_data Message-ID: <20260324083903.414352aa@gandalf.local.home> In-Reply-To: <20260324084804.375764-1-martin@kaiser.cx> References: <20260323102020.239567-1-martin@kaiser.cx> <20260324084804.375764-1-martin@kaiser.cx> 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-Rspamd-Queue-Id: D155117 X-Stat-Signature: kcio7beqtmqt5dc1f7wi5aumf58khno8 X-Rspamd-Server: rspamout03 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1+HLER84+fSlHH/X84/OfEjdWtC5reKrSg= X-HE-Tag: 1774355902-599556 X-HE-Meta: U2FsdGVkX19Nfof1UU2EMvymvjD7ssybtCHLQxLMmjalIyr+I4zsDWFGNiM3t+K1D63x1WmGUymLs6waFlVIXBJIvSFOpeCIUdBsjOz7wYksELEKgL1kEWpsvQbOsrnsIuqk5eIMzHJvtLNEDTCHLcoD+w/vBJRswjyLLJzEolZrbL7FLmci9JUbGzqAJ1ggQx5s+ddVhBjVl2GciIkBYtKCmj76UpvyfJk/zLl8a6m2S20LcEZ2w5RQppZaS6xX4gdukinqmf6Bbo/20O/OFYTLWtqm3zuncfMaF8e2AWUPUWx5LqhOI0Nge9hbJOgnWVr0EA769bhVXliQ/EeOfNUdO16a8SCDtVpi2H5fMdxIoaV3s8prBGdqqZBE/0m6r+pPCLIt4Vor+3V9a4iDww== On Tue, 24 Mar 2026 09:47:08 +0100 Martin Kaiser wrote: Hi Martin, First, please do not send a v2 as a reply to v1. A new version should always start a new mail thread. > If fprobe_entry does not fill the allocated fgraph_data completely, the > unused part does not have to be zeroed. > > fgraph_data is a short-lived part of the shadow stack. The preceding > length field allows locating the end regardless of the content. > > Signed-off-by: Martin Kaiser > --- > v2: But to maintain a link to the previous version, I recommend adding here: Changes since v1: https://lore.kernel.org/all/20260324084804.375764-1-martin@kaiser.cx > - remove the memset instead of fixing the length > > kernel/trace/fprobe.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c > index dcadf1d23b8a..56d145017902 100644 > --- a/kernel/trace/fprobe.c > +++ b/kernel/trace/fprobe.c > @@ -450,8 +450,6 @@ static int fprobe_fgraph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops > used += FPROBE_HEADER_SIZE_IN_LONG + size_words; > } > } > - if (used < reserved_words) > - memset(fgraph_data + used, 0, reserved_words - used); > > /* If any exit_handler is set, data must be used. */ > return used != 0; As for the patch, Reviewed-by: Steven Rostedt (Google) -- Steve