From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 47587E6FE51 for ; Wed, 24 Dec 2025 01:11:41 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A53AC10E2F2; Wed, 24 Dec 2025 01:11:40 +0000 (UTC) Received: from outboundhk.mxmail.xiaomi.com (outboundhk.mxmail.xiaomi.com [118.143.206.90]) by gabe.freedesktop.org (Postfix) with ESMTP id 3A16F10E2F2 for ; Wed, 24 Dec 2025 01:11:38 +0000 (UTC) X-CSE-ConnectionGUID: H1pX4pXDTgKSu6gQX2U8bA== X-CSE-MsgGUID: qU21qwFcSiGZONs5d8diDQ== X-IronPort-AV: E=Sophos;i="6.21,172,1763395200"; d="scan'208,217";a="136357648" From: =?gb2312?B?uN/P6A==?= To: Steven Rostedt , Xiang Gao CC: "sumit.semwal@linaro.org" , "christian.koenig@amd.com" , "mhiramat@kernel.org" , "linux-media@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , "linux-kernel@vger.kernel.org" , "mathieu.desnoyers@efficios.com" , "dhowells@redhat.com" , "kuba@kernel.org" , "brauner@kernel.org" , "akpm@linux-foundation.org" , "linux-trace-kernel@vger.kernel.org" Subject: =?gb2312?B?tPC4tDogW0V4dGVybmFsIE1haWxdUmU6IFtQQVRDSCB2OV0gZG1hLWJ1Zjog?= =?gb2312?Q?add_some_tracepoints_to_debug.?= Thread-Topic: [External Mail]Re: [PATCH v9] dma-buf: add some tracepoints to debug. 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ok, thanks.

=B7=A2=BC=FE=C8=CB: Steve= n Rostedt <rostedt@goodmis.org>
=B7=A2=CB=CD=CA=B1=BC=E4: 2025=C4=EA12=D4=C224=C8=D5 0:44:24
=CA=D5=BC=FE=C8=CB: Xiang Gao
=B3=AD=CB=CD: sumit.semwal@linaro.org; christian.koenig@amd.com; mhi= ramat@kernel.org; linux-media@vger.kernel.org; dri-devel@lists.freedesktop.= org; linux-kernel@vger.kernel.org; mathieu.desnoyers@efficios.com; dhowells= @redhat.com; kuba@kernel.org; brauner@kernel.org; akpm@linux-foundation.org; linux-trace-kernel@vger.kernel.org; =B8=DF=CF= =E8
=D6=F7=CC=E2: [External Mail]Re: [PATCH v9] dma-buf: add some tracep= oints to debug.
 
[=CD=E2=B2=BF=D3=CA=BC=FE] =B4=CB=D3=CA=BC=FE=C0= =B4=D4=B4=D3=DA=D0=A1=C3=D7=B9=AB=CB=BE=CD=E2=B2=BF=A3=AC=C7=EB=BD=F7=C9=F7= =B4=A6=C0=ED=A1=A3=C8=F4=B6=D4=D3=CA=BC=FE=B0=B2=C8=AB=D0=D4=B4=E6=D2=C9=A3= =AC=C7=EB=BD=AB=D3=CA=BC=FE=D7=AA=B7=A2=B8=F8misec@xiaomi.com=BD=F8=D0=D0= =B7=B4=C0=A1

On Tue, 23 Dec 2025 11:27:49 +0800
Xiang Gao <gxxa03070307@gmail.com> wrote:

>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/dma_buf.h>
> +
> +/*
> + * dmabuf->name must be accessed with holding dmabuf->name_= lock.
> + * we need to take the lock around the tracepoint call itself whe= re
> + * it is called in the code.
> + *
> + * Note: FUNC##_enabled() is a static branch that will only
> + *       be set when the trace even= t is enabled.
> + */
> +#define DMA_BUF_TRACE(FUNC, ...)     &nb= sp;            =             &nb= sp;      \
> +     do {      =             &nb= sp;            =             &nb= sp;            =             &nb= sp;            =    \
> +           = ;  if (FUNC##_enabled()) {       &n= bsp;            = ;            &n= bsp;        \
> +           = ;          guard(spinlock)(&am= p;dmabuf->name_lock);    \
> +           = ;          FUNC(__VA_ARGS__);&= nbsp;           &nbs= p;            &= nbsp;           &nbs= p;        \
> +           = ;  } else if (IS_ENABLED(CONFIG_LOCKDEP)) {    &nb= sp;   \
> +           = ;          /* Expose this lock= when lockdep is enabled */  \
> +           = ;          guard(spinlock)(&am= p;dmabuf->name_lock);    \
> +           = ;  }           =             &nb= sp;            =             &nb= sp;            =             &nb= sp;            = \
> +     } while (0)
> +

I hate to make another comment here, but I was just thinking that this can<= br> be made to look a little nicer. Basically, we want to make sure that when LOCKDEP is active, we always take the lock. But we also need to take the lock when tracing is enabled. The tracepoint itself is a static branch,
which means it is a nop when not active, so there's no real problem with calling it. Thus, this could look better as:

#define DMA_BUF_TRACE(FUNC, ...)       &= nbsp;           &nbs= p;            &= nbsp;       \
        do {    &nbs= p;            &= nbsp;           &nbs= p;            &= nbsp;           &nbs= p;     \
            &nb= sp;   /* Always expose lock if lockdep is enabled */  &= nbsp;       \
            &nb= sp;   if (IS_ENABLED(CONFIG_LOCKDEP) || FUNC##_enabled()) { =   \
            &nb= sp;           guard(spinl= ock)(&dmabuf->name_lock);       &= nbsp;    \
            &nb= sp;           FUNC(__VA_A= RGS__);           &n= bsp;            = ;      \
            &nb= sp;   }         &nbs= p;            &= nbsp;           &nbs= p;            &= nbsp;       \
        } while (0)


-- Steve
 --_000_49db0d7370224e14ad7788b280bd1602xiaomicom_--