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 F1C221F542A; Thu, 19 Jun 2025 03:45:20 +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=1750304723; cv=none; b=D4SmGxJVU6vulkRW4y4DRznstWubaLEBd0SANnYrOqmkdDdVcLEiNemih6TsSsHpQeCWTO5jwk/c13AIvFZSmr24gaj33DeI6aCwfSK9ug+y4FGwK3UBzuic+78fT+wZ0/DDhrA9zYVs52/5kotUNaC2gGEY3p+IqK1A3w/+4HA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750304723; c=relaxed/simple; bh=9CzMphxe3lW5Q3aLp/MGYbMjrc/VDOWnRy/s1Jiwmv0=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=Is0PvEYo10L6WdeuECQXbh3zXnxS5uwpPFYwi6wqytoVNcdy1OEJPZrFEi0cAf6aHre1aZcTqR1DiH/+kUvgamoXTcl9mmVM2mQfRgLMUR7xQYE7QBpYoMeVPMh0WvCeQ2KFNISB8Qow4XtT/I2AEq6uVg3R11e38qoex7F+oE0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MXvzKPqU; 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="MXvzKPqU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 67E1CC4CEEA; Thu, 19 Jun 2025 03:45:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750304720; bh=9CzMphxe3lW5Q3aLp/MGYbMjrc/VDOWnRy/s1Jiwmv0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=MXvzKPqUZiVQLYrAn65ar80qKZyE29uppXnHTNGE5EpWmEGYeAld594V8mSewyozp qL+uz6D33wRi4CxdN+FPQ/T0ta/Fds8j7VYG+XSwWSWr5QG1Q7hkVzewEmKW4tx6TE 4gk08HPKQ2GsDS5i3Ws590JY1CKBN8JaFLM50uYuIlvvc/URj9m3w4Tl9wdJNuvz97 VKdliSZ4ccaPh5Uj1xPCUSjdodo2yVNSP0QSI23kLexXybQjPH2jRW5LSfl4FzpzHO nG0Yl0MikXbHcuKicd2N0fFnszhzNnCTpoZ5vZSewP2lJGsFDmBJWZUU2jZuZMaRXV AH3IowBPDFqFw== Date: Thu, 19 Jun 2025 12:45:17 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: LKML , Linux Trace Kernel , Masami Hiramatsu , Mathieu Desnoyers , Mark Rutland Subject: Re: [PATCH] fgraph: Keep track of when fgraph_ops are registered or not Message-Id: <20250619124517.3e6665439e1794918e83f1b6@kernel.org> In-Reply-To: <20250618073117.024efb2e@gandalf.local.home> References: <20250618073117.024efb2e@gandalf.local.home> 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 On Wed, 18 Jun 2025 07:31:17 -0400 Steven Rostedt wrote: > From: Steven Rostedt > > Add a warning if unregister_ftrace_graph() is called without ever > registering it, or if register_ftrace_graph() is called twice. This can > detect errors when they happen and not later when there's a side effect: > > Link: https://lore.kernel.org/all/20250617120830.24fbdd62@gandalf.local.home/ > > Signed-off-by: Steven Rostedt (Google) > --- > kernel/trace/fgraph.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c > index c5b207992fb4..c6bb6c68764f 100644 > --- a/kernel/trace/fgraph.c > +++ b/kernel/trace/fgraph.c > @@ -1325,6 +1325,10 @@ int register_ftrace_graph(struct fgraph_ops *gops) > int ret = 0; > int i = -1; > > + if (WARN_ONCE(gops->ops.flags & FTRACE_OPS_FL_GRAPH, > + "function graph ops registered again")) > + return -EBUSY; > + > guard(mutex)(&ftrace_lock); > > if (!fgraph_stack_cachep) { > @@ -1401,17 +1405,21 @@ void unregister_ftrace_graph(struct fgraph_ops *gops) > { > int command = 0; > > + if (WARN_ONCE(!(gops->ops.flags & FTRACE_OPS_FL_GRAPH), > + "function graph ops unregistered without registering")) > + return; > + > guard(mutex)(&ftrace_lock); > > if (unlikely(!ftrace_graph_active)) > - return; > + goto out; > > if (unlikely(gops->idx < 0 || gops->idx >= FGRAPH_ARRAY_SIZE || > fgraph_array[gops->idx] != gops)) > - return; > + goto out; > > if (fgraph_lru_release_index(gops->idx) < 0) > - return; > + goto out; > > fgraph_array[gops->idx] = &fgraph_stub; > > @@ -1434,4 +1442,6 @@ void unregister_ftrace_graph(struct fgraph_ops *gops) > unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL); > } > gops->saved_func = NULL; > + out: > + gops->ops.flags = 0; Can we make it cleaning only FTRACE_OPS_FL_GRAPH flag here? Or, ops.flags should be set again before registering it? Thank you, > } > -- > 2.47.2 > -- Masami Hiramatsu (Google)