From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 8ADC94C6811; Mon, 7 Sep 2026 13:28:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788787737; cv=none; b=cTl7TdhjsCa4CaMs5vR7nU2i/y1wTvYcc8ifXpaGEcAY8NMX1PZbterfBWEkNntmg57DMqfW18Mf4RgmUjvVW2QdSBythelTs8myEtQxXQxZ7+mbnwXkPQQ7VQUnx6YmkKAClqwkzjT8j7zKqQ6+DKL0JRTsj7lgcDEGai5y3cI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788787737; c=relaxed/simple; bh=Q43zjFngUH4CVRm0yM8HzVAnPDiw5923YGyUdTIL2X8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Y8sIYRa04BG+r0YasISF83TtOIpPA261kZ2vk7IiCrtVT3ZRXRnVK3iAHh1snt51Ibr0R8dwxNsO62XjjDz27t+mRku2V6CdCIMOs83GKDUK6MoI3LczpZwafWOkWeyFyEKJTKX5GDhqlv54Xpx5SJqh2ozc5Q+sGOqrgt6zTXA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=iDqy+gXd; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="iDqy+gXd" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B49641476; Mon, 7 Sep 2026 06:28:47 -0700 (PDT) Received: from [10.0.152.207] (unknown [10.0.152.207]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 893583F7D8; Mon, 7 Sep 2026 06:28:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788787731; bh=Q43zjFngUH4CVRm0yM8HzVAnPDiw5923YGyUdTIL2X8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=iDqy+gXdsbWjQJPd91C1nM1zZ+xgWeS11WliE9Osu1N/a3Fjgd/2p2Xx/8MhgRZLR ucE++QR5nAlr8Qq4g07e9u7HQKvsSBNE2oaru/6qRuQM+o3PTaTePwbVhyW9QXlP4A f0nPXWjg8bGVTYGo8ofymc0I7B9rALdmwVs+EelI= Message-ID: Date: Mon, 7 Sep 2026 14:28:47 +0100 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [BUG/PATCH] drivers/usb/mtu3: Work around mtu3_log_ep double-indirection issue To: paulmck@kernel.org, Chunfeng Yun , Greg Kroah-Hartman , rostedt@goodmis.org Cc: linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org References: Content-Language: en-GB From: Vladimir Murzin In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/4/26 00:59, Paul E. McKenney wrote: > This is more bug report than patch, but this patch does suppress the > splat, so there is that. ;-) > > Kernels built with either KASAN or KCSAN produce this splat: > I see it on kernel w/o KASAN or KCSAN. IIUC, this is new check introduced by b5cc230af5e5 ("tracing: Warn when an event dereferences a pointer in TP_printk()") so adding Steven :) > [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma > [ 0.000000] ------------[ cut here ]------------ > [ 0.000000] Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma > [ 0.000000] WARNING: kernel/trace/trace_events.c:420 at test_double_dereference+0x144/0x14c, CPU#0: swapper/0/0 > [ 0.000000] Modules linked in: > [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 7.3.0-rc1 #15247 PREEMPT > [ 0.000000] Hardware name: linux,dummy-virt (DT) > [ 0.000000] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 0.000000] pc : test_double_dereference+0x144/0x14c > [ 0.000000] lr : test_double_dereference+0x144/0x14c > [ 0.000000] sp : ffffc80aa7633bf0 > [ 0.000000] x29: ffffc80aa7633bf0 x28: ffffc80aa7c0f047 x27: 000508b58019388f > [ 0.000000] x26: 0000000000000003 x25: 0000000000000007 x24: ffffc80aa5fceff8 > [ 0.000000] x23: ffffc80aa7c0f05a x22: ffffc80aa64edfe8 x21: ffffc80aa7c0fce8 > [ 0.000000] x20: ffffc80aa7c0f047 x19: 0000000000000013 x18: 0000000000000001 > [ 0.000000] x17: 6572656420656c62 x16: 756f642073616820 x15: 746c61685f746573 > [ 0.000000] x14: 0000000000000000 x13: ffff000139d90000 x12: 0000000000000045 > [ 0.000000] x11: 00000000000000cf x10: ffff00013f546428 x9 : ffff000139d90000 > [ 0.000000] x8 : 3fffffffffffc000 x7 : 0000000000000001 x6 : 0000000000000001 > [ 0.000000] x5 : ffff00013f4e6440 x4 : 0000000000000000 x3 : 0000000000000000 > [ 0.000000] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffffc80aa764a700 > [ 0.000000] Call trace: > [ 0.000000] test_double_dereference+0x144/0x14c (P) > [ 0.000000] trace_event_raw_init+0x37c/0x5d8 > [ 0.000000] event_init+0x34/0xc0 > [ 0.000000] trace_event_init+0xec/0x588 > [ 0.000000] trace_init+0x24/0x6e0 > [ 0.000000] start_kernel+0x4a0/0x8ec > [ 0.000000] __primary_switched+0x88/0x90 > [ 0.000000] irq event stamp: 0 > [ 0.000000] hardirqs last enabled at (0): [<0000000000000000>] 0x0 > [ 0.000000] hardirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 0.000000] softirqs last enabled at (0): [<0000000000000000>] 0x0 > [ 0.000000] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 0.000000] ---[ end trace 0000000000000000 ]--- > [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_disable has double dereference in TP_printk: &REC->gpd_ring->dma > [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_enable has double dereference in TP_printk: &REC->gpd_ring->dma > > Apparently, the code should instead create another entry in > TP_STRUCT__entry(), and do the double-indirection TP_fast_assign() instead > of TP_printk(). But simply removing the offending double indirection > in TP_printk() gets this splat out of the way of other debugging. > Indeed, splat has gone after applying the patch. Thanks Vladimir > Signed-off-by: Paul E. McKenney > Cc: Chunfeng Yun > Cc: Greg Kroah-Hartman > Cc: > Cc: > Cc: > > diff --git a/drivers/usb/mtu3/mtu3_trace.h b/drivers/usb/mtu3/mtu3_trace.h > index 89870175d63561..7c414e196d5871 100644 > --- a/drivers/usb/mtu3/mtu3_trace.h > +++ b/drivers/usb/mtu3/mtu3_trace.h > @@ -236,11 +236,11 @@ DECLARE_EVENT_CLASS(mtu3_log_ep, > __entry->direction = mep->is_in; > __entry->gpd_ring = &mep->gpd_ring; > ), > - TP_printk("%s: type %s maxp %d slot %d mult %d burst %d ring %p/%pad flags %c:%c%c%c:%c", > + TP_printk("%s: type %s maxp %d slot %d mult %d burst %d ring %p flags %c:%c%c%c:%c", > __get_str(name), usb_ep_type_string(__entry->type), > __entry->maxp, __entry->slot, > __entry->mult, __entry->maxburst, > - __entry->gpd_ring, &__entry->gpd_ring->dma, > + __entry->gpd_ring, > __entry->flags & MTU3_EP_ENABLED ? 'E' : 'e', > __entry->flags & MTU3_EP_STALL ? 'S' : 's', > __entry->flags & MTU3_EP_WEDGE ? 'W' : 'w', >