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Fri, 9 Apr 2021 05:07:11 +0000 Received: from DM5PR04MB0762.namprd04.prod.outlook.com ([fe80::4c98:aeb:87a8:13ad]) by DM5PR04MB0762.namprd04.prod.outlook.com ([fe80::4c98:aeb:87a8:13ad%5]) with mapi id 15.20.4020.017; Fri, 9 Apr 2021 05:07:11 +0000 From: Zev Weiss To: Andrew Jeffery CC: "openipmi-developer@lists.sourceforge.net" , "openbmc@lists.ozlabs.org" , "minyard@acm.org" , "devicetree@vger.kernel.org" , "ryan_chen@aspeedtech.com" , "tmaimon77@gmail.com" , "linux-aspeed@lists.ozlabs.org" , "avifishman70@gmail.com" , "venture@google.com" , "linus.walleij@linaro.org" , "linux-kernel@vger.kernel.org" , "tali.perry1@gmail.com" , "linux-gpio@vger.kernel.org" , "robh+dt@kernel.org" , "lee.jones@linaro.org" , "chiawei_wang@aspeedtech.com" , "linux-arm-kernel@lists.infradead.org" , "benjaminfair@google.com" Subject: Re: [PATCH v2 15/21] ipmi: kcs_bmc: Don't enforce single-open policy in the kernel Thread-Topic: [PATCH v2 15/21] ipmi: kcs_bmc: Don't enforce single-open policy in the kernel Thread-Index: AQHXLP4yV1bPwWXIUE6uiUHJ1sIkdw== Date: Fri, 9 Apr 2021 05:07:11 +0000 Message-ID: References: <20210319062752.145730-1-andrew@aj.id.au> <20210319062752.145730-15-andrew@aj.id.au> In-Reply-To: <20210319062752.145730-15-andrew@aj.id.au> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: aj.id.au; 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charset="us-ascii" Content-ID: <4AFF152F614E864091DBF9A7AB886B87@namprd04.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: equinix.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: DM5PR04MB0762.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 12788c7b-e50f-4a19-e12f-08d8fb155501 X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Apr 2021 05:07:11.1506 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72adb271-2fc7-4afe-a5ee-9de6a59f6bfb X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: /fZl6HVF5n+m30geKhwEbIGHPif8SYJ+knyeCNrqM1sE8xh0bP0CV18msaU56zR8tlxTJ/H02jIn+T5qS8Y2+Q== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR04MB1034 X-Proofpoint-GUID: xoTdrgzNs9ersZl9TD_dsMaivlxdYq4U X-Proofpoint-ORIG-GUID: xoTdrgzNs9ersZl9TD_dsMaivlxdYq4U X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-04-09_03:2021-04-08,2021-04-09 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 lowpriorityscore=0 phishscore=0 impostorscore=0 suspectscore=0 malwarescore=0 bulkscore=0 adultscore=0 mlxlogscore=999 mlxscore=0 spamscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104060000 definitions=main-2104090036 Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org On Fri, Mar 19, 2021 at 01:27:46AM CDT, Andrew Jeffery wrote: >Soon it will be possible for one KCS device to have multiple associated >chardevs exposed to userspace (for IPMI and raw-style access). However, >don't prevent userspace from: > >1. Opening more than one chardev at a time, or >2. Opening the same chardev more than once. > >System behaviour is undefined for both classes of multiple access, so >userspace must manage itself accordingly. > >The implementation delivers IBF and OBF events to the first chardev >client to associate with the KCS device. An open on a related chardev >cannot associate its client with the KCS device and so will not >receive notification of events. However, any fd on any chardev may race >their accesses to the data and status registers. > >Signed-off-by: Andrew Jeffery >--- > drivers/char/ipmi/kcs_bmc.c | 34 ++++++++++------------------- > drivers/char/ipmi/kcs_bmc_aspeed.c | 3 +-- > drivers/char/ipmi/kcs_bmc_npcm7xx.c | 3 +-- > 3 files changed, 14 insertions(+), 26 deletions(-) > >diff --git a/drivers/char/ipmi/kcs_bmc.c b/drivers/char/ipmi/kcs_bmc.c >index 05bbb72418b2..2fafa9541934 100644 >--- a/drivers/char/ipmi/kcs_bmc.c >+++ b/drivers/char/ipmi/kcs_bmc.c >@@ -55,24 +55,12 @@ EXPORT_SYMBOL(kcs_bmc_update_status); > int kcs_bmc_handle_event(struct kcs_bmc_device *kcs_bmc) > { > struct kcs_bmc_client *client; >- int rc; >+ int rc =3D KCS_BMC_EVENT_NONE; > > spin_lock(&kcs_bmc->lock); > client =3D kcs_bmc->client; >- if (client) { >+ if (!WARN_ON_ONCE(!client)) > rc =3D client->ops->event(client); The double-negation split by a macro seems a bit confusing to me readability-wise; could we simplify to something like if (client) rc =3D client->ops->event(client); else WARN_ONCE(); ? >- } else { >- u8 status; >- >- status =3D kcs_bmc_read_status(kcs_bmc); >- if (status & KCS_BMC_STR_IBF) { >- /* Ack the event by reading the data */ >- kcs_bmc_read_data(kcs_bmc); >- rc =3D KCS_BMC_EVENT_HANDLED; >- } else { >- rc =3D KCS_BMC_EVENT_NONE; >- } >- } > spin_unlock(&kcs_bmc->lock); > > return rc; >@@ -81,26 +69,28 @@ EXPORT_SYMBOL(kcs_bmc_handle_event); > > int kcs_bmc_enable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bmc_= client *client) > { >- int rc; >- > spin_lock_irq(&kcs_bmc->lock); >- if (kcs_bmc->client) { >- rc =3D -EBUSY; >- } else { >+ if (!kcs_bmc->client) { >+ u8 mask =3D KCS_BMC_EVENT_TYPE_IBF; >+ > kcs_bmc->client =3D client; >- rc =3D 0; >+ kcs_bmc_update_event_mask(kcs_bmc, mask, mask); > } > spin_unlock_irq(&kcs_bmc->lock); > >- return rc; >+ return 0; Since this function appears to be infallible now, should it just return void? (Might be more churn than it's worth...shrug.) > } > EXPORT_SYMBOL(kcs_bmc_enable_device); > > void kcs_bmc_disable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bm= c_client *client) > { > spin_lock_irq(&kcs_bmc->lock); >- if (client =3D=3D kcs_bmc->client) >+ if (client =3D=3D kcs_bmc->client) { >+ u8 mask =3D KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE; >+ >+ kcs_bmc_update_event_mask(kcs_bmc, mask, 0); > kcs_bmc->client =3D NULL; >+ } > spin_unlock_irq(&kcs_bmc->lock); > } > EXPORT_SYMBOL(kcs_bmc_disable_device); >diff --git a/drivers/char/ipmi/kcs_bmc_aspeed.c b/drivers/char/ipmi/kcs_bm= c_aspeed.c >index 5f26471c038c..271845eb2e26 100644 >--- a/drivers/char/ipmi/kcs_bmc_aspeed.c >+++ b/drivers/char/ipmi/kcs_bmc_aspeed.c >@@ -419,8 +419,7 @@ static int aspeed_kcs_probe(struct platform_device *pd= ev) > > platform_set_drvdata(pdev, priv); > >- aspeed_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EV= ENT_TYPE_OBE), >- KCS_BMC_EVENT_TYPE_IBF); >+ aspeed_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EV= ENT_TYPE_OBE), 0); > aspeed_kcs_enable_channel(kcs_bmc, true); > > rc =3D kcs_bmc_add_device(&priv->kcs_bmc); >diff --git a/drivers/char/ipmi/kcs_bmc_npcm7xx.c b/drivers/char/ipmi/kcs_b= mc_npcm7xx.c >index c2032728a03d..fdf35cad2eba 100644 >--- a/drivers/char/ipmi/kcs_bmc_npcm7xx.c >+++ b/drivers/char/ipmi/kcs_bmc_npcm7xx.c >@@ -207,8 +207,7 @@ static int npcm7xx_kcs_probe(struct platform_device *p= dev) > if (rc) > return rc; > >- npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_E= VENT_TYPE_OBE), >- KCS_BMC_EVENT_TYPE_IBF); >+ npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_E= VENT_TYPE_OBE), 0); > npcm7xx_kcs_enable_channel(kcs_bmc, true); > > pr_info("channel=3D%u idr=3D0x%x odr=3D0x%x str=3D0x%x\n", >--=20 >2.27.0 >= 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 X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,PDS_BAD_THREAD_QP_64,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB7C0C43460 for ; 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Fri, 9 Apr 2021 05:07:11 +0000 From: Zev Weiss To: Andrew Jeffery Subject: Re: [PATCH v2 15/21] ipmi: kcs_bmc: Don't enforce single-open policy in the kernel Thread-Topic: [PATCH v2 15/21] ipmi: kcs_bmc: Don't enforce single-open policy in the kernel Thread-Index: AQHXLP4yV1bPwWXIUE6uiUHJ1sIkdw== Date: Fri, 9 Apr 2021 05:07:11 +0000 Message-ID: References: <20210319062752.145730-1-andrew@aj.id.au> <20210319062752.145730-15-andrew@aj.id.au> In-Reply-To: <20210319062752.145730-15-andrew@aj.id.au> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: aj.id.au; dkim=none (message not signed) header.d=none;aj.id.au; dmarc=none action=none header.from=equinix.com; x-originating-ip: [24.181.166.149] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 12788c7b-e50f-4a19-e12f-08d8fb155501 x-ms-traffictypediagnostic: DM5PR04MB1034: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:6108; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; 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charset="us-ascii" Content-ID: <4AFF152F614E864091DBF9A7AB886B87@namprd04.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: equinix.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: DM5PR04MB0762.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 12788c7b-e50f-4a19-e12f-08d8fb155501 X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Apr 2021 05:07:11.1506 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72adb271-2fc7-4afe-a5ee-9de6a59f6bfb X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: /fZl6HVF5n+m30geKhwEbIGHPif8SYJ+knyeCNrqM1sE8xh0bP0CV18msaU56zR8tlxTJ/H02jIn+T5qS8Y2+Q== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR04MB1034 X-Proofpoint-GUID: xoTdrgzNs9ersZl9TD_dsMaivlxdYq4U X-Proofpoint-ORIG-GUID: xoTdrgzNs9ersZl9TD_dsMaivlxdYq4U X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-04-09_03:2021-04-08, 2021-04-09 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 lowpriorityscore=0 phishscore=0 impostorscore=0 suspectscore=0 malwarescore=0 bulkscore=0 adultscore=0 mlxlogscore=999 mlxscore=0 spamscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104060000 definitions=main-2104090036 X-BeenThere: openbmc@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development list for OpenBMC List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "devicetree@vger.kernel.org" , "chiawei_wang@aspeedtech.com" , "ryan_chen@aspeedtech.com" , "tmaimon77@gmail.com" , "minyard@acm.org" , "avifishman70@gmail.com" , "venture@google.com" , "openbmc@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" , "tali.perry1@gmail.com" , "linux-gpio@vger.kernel.org" , "robh+dt@kernel.org" , "linux-arm-kernel@lists.infradead.org" , "openipmi-developer@lists.sourceforge.net" , "lee.jones@linaro.org" , "linus.walleij@linaro.org" , "linux-aspeed@lists.ozlabs.org" , "benjaminfair@google.com" Errors-To: openbmc-bounces+openbmc=archiver.kernel.org@lists.ozlabs.org Sender: "openbmc" On Fri, Mar 19, 2021 at 01:27:46AM CDT, Andrew Jeffery wrote: >Soon it will be possible for one KCS device to have multiple associated >chardevs exposed to userspace (for IPMI and raw-style access). However, >don't prevent userspace from: > >1. Opening more than one chardev at a time, or >2. Opening the same chardev more than once. > >System behaviour is undefined for both classes of multiple access, so >userspace must manage itself accordingly. > >The implementation delivers IBF and OBF events to the first chardev >client to associate with the KCS device. An open on a related chardev >cannot associate its client with the KCS device and so will not >receive notification of events. However, any fd on any chardev may race >their accesses to the data and status registers. > >Signed-off-by: Andrew Jeffery >--- > drivers/char/ipmi/kcs_bmc.c | 34 ++++++++++------------------- > drivers/char/ipmi/kcs_bmc_aspeed.c | 3 +-- > drivers/char/ipmi/kcs_bmc_npcm7xx.c | 3 +-- > 3 files changed, 14 insertions(+), 26 deletions(-) > >diff --git a/drivers/char/ipmi/kcs_bmc.c b/drivers/char/ipmi/kcs_bmc.c >index 05bbb72418b2..2fafa9541934 100644 >--- a/drivers/char/ipmi/kcs_bmc.c >+++ b/drivers/char/ipmi/kcs_bmc.c >@@ -55,24 +55,12 @@ EXPORT_SYMBOL(kcs_bmc_update_status); > int kcs_bmc_handle_event(struct kcs_bmc_device *kcs_bmc) > { > struct kcs_bmc_client *client; >- int rc; >+ int rc =3D KCS_BMC_EVENT_NONE; > > spin_lock(&kcs_bmc->lock); > client =3D kcs_bmc->client; >- if (client) { >+ if (!WARN_ON_ONCE(!client)) > rc =3D client->ops->event(client); The double-negation split by a macro seems a bit confusing to me readability-wise; could we simplify to something like if (client) rc =3D client->ops->event(client); else WARN_ONCE(); ? >- } else { >- u8 status; >- >- status =3D kcs_bmc_read_status(kcs_bmc); >- if (status & KCS_BMC_STR_IBF) { >- /* Ack the event by reading the data */ >- kcs_bmc_read_data(kcs_bmc); >- rc =3D KCS_BMC_EVENT_HANDLED; >- } else { >- rc =3D KCS_BMC_EVENT_NONE; >- } >- } > spin_unlock(&kcs_bmc->lock); > > return rc; >@@ -81,26 +69,28 @@ EXPORT_SYMBOL(kcs_bmc_handle_event); > > int kcs_bmc_enable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bmc_= client *client) > { >- int rc; >- > spin_lock_irq(&kcs_bmc->lock); >- if (kcs_bmc->client) { >- rc =3D -EBUSY; >- } else { >+ if (!kcs_bmc->client) { >+ u8 mask =3D KCS_BMC_EVENT_TYPE_IBF; >+ > kcs_bmc->client =3D client; >- rc =3D 0; >+ kcs_bmc_update_event_mask(kcs_bmc, mask, mask); > } > spin_unlock_irq(&kcs_bmc->lock); > >- return rc; >+ return 0; Since this function appears to be infallible now, should it just return void? (Might be more churn than it's worth...shrug.) > } > EXPORT_SYMBOL(kcs_bmc_enable_device); > > void kcs_bmc_disable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bm= c_client *client) > { > spin_lock_irq(&kcs_bmc->lock); >- if (client =3D=3D kcs_bmc->client) >+ if (client =3D=3D kcs_bmc->client) { >+ u8 mask =3D KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE; >+ >+ kcs_bmc_update_event_mask(kcs_bmc, mask, 0); > kcs_bmc->client =3D NULL; >+ } > spin_unlock_irq(&kcs_bmc->lock); > } > EXPORT_SYMBOL(kcs_bmc_disable_device); >diff --git a/drivers/char/ipmi/kcs_bmc_aspeed.c b/drivers/char/ipmi/kcs_bm= c_aspeed.c >index 5f26471c038c..271845eb2e26 100644 >--- a/drivers/char/ipmi/kcs_bmc_aspeed.c >+++ b/drivers/char/ipmi/kcs_bmc_aspeed.c >@@ -419,8 +419,7 @@ static int aspeed_kcs_probe(struct platform_device *pd= ev) > > platform_set_drvdata(pdev, priv); > >- aspeed_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EV= ENT_TYPE_OBE), >- KCS_BMC_EVENT_TYPE_IBF); >+ aspeed_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EV= ENT_TYPE_OBE), 0); > aspeed_kcs_enable_channel(kcs_bmc, true); > > rc =3D kcs_bmc_add_device(&priv->kcs_bmc); >diff --git a/drivers/char/ipmi/kcs_bmc_npcm7xx.c b/drivers/char/ipmi/kcs_b= mc_npcm7xx.c >index c2032728a03d..fdf35cad2eba 100644 >--- a/drivers/char/ipmi/kcs_bmc_npcm7xx.c >+++ b/drivers/char/ipmi/kcs_bmc_npcm7xx.c >@@ -207,8 +207,7 @@ static int npcm7xx_kcs_probe(struct platform_device *p= dev) > if (rc) > return rc; > >- npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_E= VENT_TYPE_OBE), >- KCS_BMC_EVENT_TYPE_IBF); >+ npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_E= VENT_TYPE_OBE), 0); > npcm7xx_kcs_enable_channel(kcs_bmc, true); > > pr_info("channel=3D%u idr=3D0x%x odr=3D0x%x str=3D0x%x\n", >--=20 >2.27.0 >= 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 X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46D84C433ED for ; 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Fri, 9 Apr 2021 05:07:11 +0000 From: Zev Weiss To: Andrew Jeffery CC: "openipmi-developer@lists.sourceforge.net" , "openbmc@lists.ozlabs.org" , "minyard@acm.org" , "devicetree@vger.kernel.org" , "ryan_chen@aspeedtech.com" , "tmaimon77@gmail.com" , "linux-aspeed@lists.ozlabs.org" , "avifishman70@gmail.com" , "venture@google.com" , "linus.walleij@linaro.org" , "linux-kernel@vger.kernel.org" , "tali.perry1@gmail.com" , "linux-gpio@vger.kernel.org" , "robh+dt@kernel.org" , "lee.jones@linaro.org" , "chiawei_wang@aspeedtech.com" , "linux-arm-kernel@lists.infradead.org" , "benjaminfair@google.com" Subject: Re: [PATCH v2 15/21] ipmi: kcs_bmc: Don't enforce single-open policy in the kernel Thread-Topic: [PATCH v2 15/21] ipmi: kcs_bmc: Don't enforce single-open policy in the kernel Thread-Index: AQHXLP4yV1bPwWXIUE6uiUHJ1sIkdw== Date: Fri, 9 Apr 2021 05:07:11 +0000 Message-ID: References: <20210319062752.145730-1-andrew@aj.id.au> <20210319062752.145730-15-andrew@aj.id.au> In-Reply-To: <20210319062752.145730-15-andrew@aj.id.au> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: aj.id.au; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Mar 19, 2021 at 01:27:46AM CDT, Andrew Jeffery wrote: >Soon it will be possible for one KCS device to have multiple associated >chardevs exposed to userspace (for IPMI and raw-style access). However, >don't prevent userspace from: > >1. Opening more than one chardev at a time, or >2. Opening the same chardev more than once. > >System behaviour is undefined for both classes of multiple access, so >userspace must manage itself accordingly. > >The implementation delivers IBF and OBF events to the first chardev >client to associate with the KCS device. An open on a related chardev >cannot associate its client with the KCS device and so will not >receive notification of events. However, any fd on any chardev may race >their accesses to the data and status registers. > >Signed-off-by: Andrew Jeffery >--- > drivers/char/ipmi/kcs_bmc.c | 34 ++++++++++------------------- > drivers/char/ipmi/kcs_bmc_aspeed.c | 3 +-- > drivers/char/ipmi/kcs_bmc_npcm7xx.c | 3 +-- > 3 files changed, 14 insertions(+), 26 deletions(-) > >diff --git a/drivers/char/ipmi/kcs_bmc.c b/drivers/char/ipmi/kcs_bmc.c >index 05bbb72418b2..2fafa9541934 100644 >--- a/drivers/char/ipmi/kcs_bmc.c >+++ b/drivers/char/ipmi/kcs_bmc.c >@@ -55,24 +55,12 @@ EXPORT_SYMBOL(kcs_bmc_update_status); > int kcs_bmc_handle_event(struct kcs_bmc_device *kcs_bmc) > { > struct kcs_bmc_client *client; >- int rc; >+ int rc = KCS_BMC_EVENT_NONE; > > spin_lock(&kcs_bmc->lock); > client = kcs_bmc->client; >- if (client) { >+ if (!WARN_ON_ONCE(!client)) > rc = client->ops->event(client); The double-negation split by a macro seems a bit confusing to me readability-wise; could we simplify to something like if (client) rc = client->ops->event(client); else WARN_ONCE(); ? >- } else { >- u8 status; >- >- status = kcs_bmc_read_status(kcs_bmc); >- if (status & KCS_BMC_STR_IBF) { >- /* Ack the event by reading the data */ >- kcs_bmc_read_data(kcs_bmc); >- rc = KCS_BMC_EVENT_HANDLED; >- } else { >- rc = KCS_BMC_EVENT_NONE; >- } >- } > spin_unlock(&kcs_bmc->lock); > > return rc; >@@ -81,26 +69,28 @@ EXPORT_SYMBOL(kcs_bmc_handle_event); > > int kcs_bmc_enable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bmc_client *client) > { >- int rc; >- > spin_lock_irq(&kcs_bmc->lock); >- if (kcs_bmc->client) { >- rc = -EBUSY; >- } else { >+ if (!kcs_bmc->client) { >+ u8 mask = KCS_BMC_EVENT_TYPE_IBF; >+ > kcs_bmc->client = client; >- rc = 0; >+ kcs_bmc_update_event_mask(kcs_bmc, mask, mask); > } > spin_unlock_irq(&kcs_bmc->lock); > >- return rc; >+ return 0; Since this function appears to be infallible now, should it just return void? (Might be more churn than it's worth...shrug.) > } > EXPORT_SYMBOL(kcs_bmc_enable_device); > > void kcs_bmc_disable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bmc_client *client) > { > spin_lock_irq(&kcs_bmc->lock); >- if (client == kcs_bmc->client) >+ if (client == kcs_bmc->client) { >+ u8 mask = KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE; >+ >+ kcs_bmc_update_event_mask(kcs_bmc, mask, 0); > kcs_bmc->client = NULL; >+ } > spin_unlock_irq(&kcs_bmc->lock); > } > EXPORT_SYMBOL(kcs_bmc_disable_device); >diff --git a/drivers/char/ipmi/kcs_bmc_aspeed.c b/drivers/char/ipmi/kcs_bmc_aspeed.c >index 5f26471c038c..271845eb2e26 100644 >--- a/drivers/char/ipmi/kcs_bmc_aspeed.c >+++ b/drivers/char/ipmi/kcs_bmc_aspeed.c >@@ -419,8 +419,7 @@ static int aspeed_kcs_probe(struct platform_device *pdev) > > platform_set_drvdata(pdev, priv); > >- aspeed_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE), >- KCS_BMC_EVENT_TYPE_IBF); >+ aspeed_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE), 0); > aspeed_kcs_enable_channel(kcs_bmc, true); > > rc = kcs_bmc_add_device(&priv->kcs_bmc); >diff --git a/drivers/char/ipmi/kcs_bmc_npcm7xx.c b/drivers/char/ipmi/kcs_bmc_npcm7xx.c >index c2032728a03d..fdf35cad2eba 100644 >--- a/drivers/char/ipmi/kcs_bmc_npcm7xx.c >+++ b/drivers/char/ipmi/kcs_bmc_npcm7xx.c >@@ -207,8 +207,7 @@ static int npcm7xx_kcs_probe(struct platform_device *pdev) > if (rc) > return rc; > >- npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE), >- KCS_BMC_EVENT_TYPE_IBF); >+ npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE), 0); > npcm7xx_kcs_enable_channel(kcs_bmc, true); > > pr_info("channel=%u idr=0x%x odr=0x%x str=0x%x\n", >-- >2.27.0 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel