Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 3 Apr 2023 17:06:11 +0300
From:   Vladimir Oltean <vladimir.oltean@nxp.com>
To:     Sean Anderson <sean.anderson@seco.com>
Cc:     Li Yang <leoyang.li@nxp.com>, linuxppc-dev@lists.ozlabs.org,
        linux-arm-kernel@lists.infradead.org,
        Scott Wood <oss@buserror.net>,
        Camelia Groza <camelia.groza@nxp.com>,
        linux-kernel@vger.kernel.org, Roy Pledge <roy.pledge@nxp.com>,
        "David S . Miller" <davem@davemloft.net>,
        Claudiu Manoil <claudiu.manoil@nxp.com>
Subject: Re: [PATCH v2 2/2] soc: fsl: qbman: Use raw spinlock for cgr_lock
Message-ID: <20230403140611.6m7xmver4wnqqigk@skbuf>
References: <20230331151413.1684105-1-sean.anderson@seco.com>
 <20230331151413.1684105-1-sean.anderson@seco.com>
 <20230331151413.1684105-2-sean.anderson@seco.com>
 <20230331151413.1684105-2-sean.anderson@seco.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230331151413.1684105-2-sean.anderson@seco.com>
 <20230331151413.1684105-2-sean.anderson@seco.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?pQQcDP2F+NNQIIx1tTud39lxnmPzxB8nSlZnsH33fs8793GULKq9TgT6jhp7?=
 =?us-ascii?Q?p0s56H5Krhi9ZUz/uiuT3ThcaOuRQyjR9P6UtZvpXEiPqnkT5FObWzCdWC10?=
 =?us-ascii?Q?RYnX3URcrK5uHapvayI0q5RwfDgLOLBR7B65/yFB3PTE8yBrvbFJgh2txLrk?=
 =?us-ascii?Q?67mEsPW4NXaUN0bjSljAsrVBJB6ZfgEuEgKEwGfMneMoA63YSGAODSbQS/y0?=
 =?us-ascii?Q?rtg7VpNsHd0wgbW6L06zwlRXsuTESXqMNNadxMLnj8Gn8GdnBj0AzVUhOZqY?=
 =?us-ascii?Q?1ssliVIT7EwN+d+IW7IuUOSmAiyWEFAvFx7fThbKlnZQQRvuja6Xvf1yGWqc?=
 =?us-ascii?Q?F1/LYr0Zbl+Pnplxfp/ZuWUAX5ZRhw8gU7dQ5dO7VTpa/2EJpfTutbh9xo3n?=
 =?us-ascii?Q?9j2d1ZzXj8jF/Ep/r+msIeJ7rJ+ZM4yjmghmV19QtipijfQvAX7kYFQzqKjr?=
 =?us-ascii?Q?GqQSsPtnVW72BLEceC1cfv37u42GFM+M97t/nqVcMJQZMPtezjTuBDK8i0CX?=
 =?us-ascii?Q?SHUX6nXgm+6rDdJ6l8FgjyxgMD8JNHzoekMGP1XzMq5jGbhtg+Et6S0AGgpn?=
 =?us-ascii?Q?jRk1q2BrTxUflria+RTO5idUdWHOo5rS7/4SITviHVssbhJEzLRSO4cfnAKB?=
 =?us-ascii?Q?RsTYw7mgnKstabz1CIhQK9uQS4iANbizvALsm2TJ36OHWBUM1j21EFOZwwmd?=
 =?us-ascii?Q?d+NPx8/tw9mCC8ytHiqVq9ZbkaUOL5ePxoORUzhn4c5dIcnm2upbNMhS8CtZ?=
 =?us-ascii?Q?BtmSCx8REp3DyPNQkuQ0q+550U+zmUGabar7ctAYdt+r7bxzZS3mRTLZ5zMI?=
 =?us-ascii?Q?y2nxuaR0tS55uSKXZRulIe01Q+RTGVS4Nja6yevAKVbqf31R997HrqSRuypJ?=
 =?us-ascii?Q?ZiMIEKFnT55Xh8HhNLeF4FQ+Gwn6OzWtVrC2jc9fVWi36IYyyO81l6JgVFyP?=
 =?us-ascii?Q?iEEO7VEvA2cPzDhj9iLmx/ZVyc1ybPWLSS9OkSIBhdjNiUWV/5LDlVnsSmV6?=
 =?us-ascii?Q?VkdhGi0Dpd3Ex6ZkApWwK3g2NEpvutgy6wmRuvhGpF1qBWxTDKIcuIU58l7/?=
 =?us-ascii?Q?M5zmoiovvvEp8UgFaGXFc2ngoVmKHNbgg7C0P+6/ixaRWGDzv4iu2WHpIXu9?=
 =?us-ascii?Q?QOgk+k6NI5caqBDtLnkXjJ6nw23dBzGLNoIdPP0WluFRtVslp3w3xst6UiV6?=
 =?us-ascii?Q?sexwim+wa03iP9XiCIWW/mB+jbI0odFaaLCj9Wa07uvHIsvAcHQ4Lc2eyu9v?=
 =?us-ascii?Q?XJofOybHnEEwWsYqdXirxmA0j4CVjYhHFWnGv6ZMTBIhcN6by9H+ryxeQszp?=
 =?us-ascii?Q?JxtNojW8nYCj00uxj9BzNZBFmhxUExsvsoFP8Bhir028HgwpBpLisHJ4jQbb?=
 =?us-ascii?Q?S2Mx7z+BYN6mriN1yVTDQWnAHYx7FUjMLqc9BJCHafVlYd3BGn9+9HeAmsNx?=
 =?us-ascii?Q?FlQcQ8WKgJeimD6HfBSkKp5Nil5BJ8dx2/Pxuhou1lOpQRwsk3AoXFeQoC9L?=
 =?us-ascii?Q?KQd6FbzzGtXncBB22SNH55f3HKyhH+CXOQlAnlrs44/jtL/Fpjtp3NIxE3Bh?=
 =?us-ascii?Q?opOkjvVV1i9SXL2cA+v8mMzhnpLR4YNgtVg26E7CSE0Z5v+iuiZqOAFTpk+k?=
 =?us-ascii?Q?cw=3D=3D?=
X-OriginatorOrg: nxp.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 6e8ab989-a56c-444e-e389-08db344c966f
X-MS-Exchange-CrossTenant-AuthSource: AM0PR04MB6452.eurprd04.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Apr 2023 14:06:15.0862
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: pVmdo2K5rAk4v1iBK+MgNrWX34t/6c8qdhD8oDjWh0K2aRlBC9ILA2BEdGoUQNjuIRDqckOvsiRSZLB34mmkMQ==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB8PR04MB7131
X-Spam-Status: No, score=0.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
        DKIM_VALID_AU,DKIM_VALID_EF,FORGED_SPF_HELO,SPF_HELO_PASS,
        T_SPF_PERMERROR autolearn=no autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, Mar 31, 2023 at 11:14:13AM -0400, Sean Anderson wrote:
> cgr_lock may be locked with interrupts already disabled by
> smp_call_function_single. As such, we must use a raw spinlock to avoid
> problems on PREEMPT_RT kernels. Although this bug has existed for a
> while, it was not apparent until commit ef2a8d5478b9 ("net: dpaa: Adjust
> queue depth on rate change") which invokes smp_call_function_single via
> qman_update_cgr_safe every time a link goes up or down.
> 
> Fixes: c535e923bb97 ("soc/fsl: Introduce DPAA 1.x QMan device driver")

Same comment about the Fixes tag.

git tag --contains c535e923bb97
v4.9
git tag --contains 96f413f47677
v4.16

Looking at https://www.kernel.org/, I see that kernel 4.14 is still
maintained but should not have this patch backported, do you agree?

> Reported-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> Link: https://lore.kernel.org/all/20230323153935.nofnjucqjqnz34ej@skbuf/
> Signed-off-by: Sean Anderson <sean.anderson@seco.com>
> ---

Anyway,

Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>