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 A1E33C3DA4A for ; Fri, 16 Aug 2024 14:12:53 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 66F3E10E7A5; Fri, 16 Aug 2024 14:12:53 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="n0r5M/ff"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2553D10E7A5 for ; Fri, 16 Aug 2024 14:12:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1723817572; x=1755353572; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to; bh=7FRMh5+/rMOU7A0yLfxjW26RdVaOlhvNAygy3LptfFI=; b=n0r5M/ffLvsxg7qUtVfbknyRjtDZWEIIMrAYkK5LgKmPrwQ4A5tYbiTF NKIxxJIrb7l5HSeYkbF9GEK232NyLY1D48Mgs8sgWo8WN2DxQ862XKleT Mz1cxfzdfIPdmIjJ/k89OWz6lw7s/LwehJ7VUCm9lsc1v5DwPfTYqnemn zPScrtSaW/1+shpumpCSmPxyAa1bbAiCxdj+lk/vqXw7TX29/gHyGbNyQ AnOcQJOToYP5XpmrICSJ8g3XnKE88vhmZrpA+2QBgOTe1qiOnVJqPlhO6 HsnpOeWvvx03/8RToSptXQ9TGNFdZPDR6ONfdrRPcfcAoiqbYk2a6EncQ g==; X-CSE-ConnectionGUID: RgulUwpQRraEcEBu/2NGOQ== X-CSE-MsgGUID: Jbpla0E+Ru6E8rGZ+AkGKQ== X-IronPort-AV: E=McAfee;i="6700,10204,11166"; a="39626977" X-IronPort-AV: E=Sophos;i="6.10,151,1719903600"; d="scan'208,217";a="39626977" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Aug 2024 07:12:52 -0700 X-CSE-ConnectionGUID: 2Nuc8imLRJKegcLFNhILsQ== X-CSE-MsgGUID: W+C9PHVxQw+vCDfYMN9wlA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.10,151,1719903600"; d="scan'208,217";a="90414855" Received: from nirmoyda-mobl.ger.corp.intel.com (HELO [10.245.146.109]) ([10.245.146.109]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Aug 2024 07:12:51 -0700 Content-Type: multipart/alternative; boundary="------------fOJ0R00DEZEQgqfpJsKj0lvY" Message-ID: <42f3736c-8611-4b8f-b24e-b803474cfaf7@linux.intel.com> Date: Fri, 16 Aug 2024 16:12:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drm/xe: Remove NULL check of lrc->bo in xe_lrc_snapshot_capture() To: Rodrigo Vivi , apoorva.singh@intel.com Cc: intel-xe@lists.freedesktop.org References: <20240816080355.897256-1-apoorva.singh@intel.com> Content-Language: en-US From: Nirmoy Das In-Reply-To: X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" This is a multi-part message in MIME format. --------------fOJ0R00DEZEQgqfpJsKj0lvY Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/16/2024 4:00 PM, Rodrigo Vivi wrote: > On Fri, Aug 16, 2024 at 01:33:55PM +0530,apoorva.singh@intel.com wrote: >> From: Apoorva Singh >> >> - lrc->bo NULL check is not needed in xe_lrc_snapshot_capture() as >> its already been taken care of in xe_lrc_init(). > I'm afraid this is not a good reason. > This snapshot capture is coming from other places and apparently > with risks of paths where bo was already freed?! I didn't think about it while suggesting this while reviewing https://patchwork.freedesktop.org/patch/608210/?series=137289&rev=1 If the bo is null then we will hit NPD while doing xe_lrc_ggtt_addr() in the next like. so I guess it should be then if (lrc->bo) { snapshot->context_desc = xe_lrc_ggtt_addr(lrc); snapshot->lrc_bo = xe_bo_get(lrc->bo); .... } Regards, Nirmoy > > why is this check bothering you so much? > >> Signed-off-by: Apoorva Singh >> --- >> drivers/gpu/drm/xe/xe_lrc.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/xe/xe_lrc.c b/drivers/gpu/drm/xe/xe_lrc.c >> index 974a9cd8c379..aec7db39c061 100644 >> --- a/drivers/gpu/drm/xe/xe_lrc.c >> +++ b/drivers/gpu/drm/xe/xe_lrc.c >> @@ -1649,7 +1649,7 @@ struct xe_lrc_snapshot *xe_lrc_snapshot_capture(struct xe_lrc *lrc) >> if (!snapshot) >> return NULL; >> >> - if (lrc->bo && lrc->bo->vm) >> + if (lrc->bo->vm) >> xe_vm_get(lrc->bo->vm); >> >> snapshot->context_desc = xe_lrc_ggtt_addr(lrc); >> -- >> 2.34.1 >> --------------fOJ0R00DEZEQgqfpJsKj0lvY Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit


On 8/16/2024 4:00 PM, Rodrigo Vivi wrote:
On Fri, Aug 16, 2024 at 01:33:55PM +0530, apoorva.singh@intel.com wrote:

From: Apoorva Singh <apoorva.singh@intel.com>

- lrc->bo NULL check is not needed in xe_lrc_snapshot_capture() as
  its already been taken care of in xe_lrc_init().

I'm afraid this is not a good reason.
This snapshot capture is coming from other places and apparently
with risks of paths where bo was already freed?!


I didn't think about it while suggesting this while reviewing https://patchwork.freedesktop.org/patch/608210/?series=137289&rev=1

If the bo is null then we will hit NPD while doing xe_lrc_ggtt_addr() in the next like. so I guess it should be then

if (lrc->bo) {

snapshot->context_desc = xe_lrc_ggtt_addr(lrc);

snapshot->lrc_bo = xe_bo_get(lrc->bo);

....

}


Regards,

Nirmoy


why is this check bothering you so much?


Signed-off-by: Apoorva Singh <apoorva.singh@intel.com>
---
 drivers/gpu/drm/xe/xe_lrc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_lrc.c b/drivers/gpu/drm/xe/xe_lrc.c
index 974a9cd8c379..aec7db39c061 100644
--- a/drivers/gpu/drm/xe/xe_lrc.c
+++ b/drivers/gpu/drm/xe/xe_lrc.c
@@ -1649,7 +1649,7 @@ struct xe_lrc_snapshot *xe_lrc_snapshot_capture(struct xe_lrc *lrc)
 	if (!snapshot)
 		return NULL;
 
-	if (lrc->bo && lrc->bo->vm)
+	if (lrc->bo->vm)
 		xe_vm_get(lrc->bo->vm);
 
 	snapshot->context_desc = xe_lrc_ggtt_addr(lrc);
-- 
2.34.1
--------------fOJ0R00DEZEQgqfpJsKj0lvY--