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From: Andrew Jeffery <andrew@aj.id.au>
To: openipmi-developer@lists.sourceforge.net,
	openbmc@lists.ozlabs.org, minyard@acm.org
Cc: devicetree@vger.kernel.org, tmaimon77@gmail.com,
	linux-aspeed@lists.ozlabs.org, avifishman70@gmail.com,
	venture@google.com, linux-kernel@vger.kernel.org,
	tali.perry1@gmail.com, robh+dt@kernel.org,
	chiawei_wang@aspeedtech.com,
	linux-arm-kernel@lists.infradead.org, benjaminfair@google.com,
	arnd@arndb.de, zweiss@equinix.com
Subject: [PATCH v3 10/16] ipmi: kcs_bmc: Don't enforce single-open policy in the kernel
Date: Mon, 10 May 2021 15:12:07 +0930	[thread overview]
Message-ID: <20210510054213.1610760-11-andrew@aj.id.au> (raw)
In-Reply-To: <20210510054213.1610760-1-andrew@aj.id.au>

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 <andrew@aj.id.au>
---
 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 7081541bb6ce..ad9ff13ba831 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);
 irqreturn_t kcs_bmc_handle_event(struct kcs_bmc_device *kcs_bmc)
 {
 	struct kcs_bmc_client *client;
-	irqreturn_t rc;
+	irqreturn_t rc = IRQ_NONE;
 
 	spin_lock(&kcs_bmc->lock);
 	client = kcs_bmc->client;
-	if (client) {
+	if (client)
 		rc = client->ops->event(client);
-	} 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 = IRQ_HANDLED;
-		} else {
-			rc = IRQ_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;
 }
 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 8b223e58d900..8a0b1e18e945 100644
--- a/drivers/char/ipmi/kcs_bmc_aspeed.c
+++ b/drivers/char/ipmi/kcs_bmc_aspeed.c
@@ -414,8 +414,7 @@ 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);
 
 	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 f8b7162fb830..ab4a8caf1270 100644
--- a/drivers/char/ipmi/kcs_bmc_npcm7xx.c
+++ b/drivers/char/ipmi/kcs_bmc_npcm7xx.c
@@ -202,8 +202,7 @@ 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


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  parent reply	other threads:[~2021-05-10  5:50 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-10  5:41 [PATCH v3 00/16] ipmi: Allow raw access to KCS devices Andrew Jeffery
2021-05-10  5:41 ` [PATCH v3 01/16] ipmi: kcs_bmc_aspeed: Use of match data to extract KCS properties Andrew Jeffery
2021-05-21  7:17   ` Zev Weiss
2021-05-10  5:41 ` [PATCH v3 02/16] ipmi: kcs_bmc: Make status update atomic Andrew Jeffery
2021-05-10  5:42 ` [PATCH v3 03/16] ipmi: kcs_bmc: Rename {read, write}_{status, data}() functions Andrew Jeffery
2021-05-10  5:42 ` [PATCH v3 04/16] ipmi: kcs_bmc: Split out kcs_bmc_cdev_ipmi Andrew Jeffery
2021-05-10  5:42 ` [PATCH v3 05/16] ipmi: kcs_bmc: Turn the driver data-structures inside-out Andrew Jeffery
2021-05-21 17:14   ` Corey Minyard
2021-05-24  0:53     ` Andrew Jeffery
2021-05-24 15:41       ` [Openipmi-developer] " Corey Minyard
2021-05-25  0:12         ` Andrew Jeffery
2021-05-10  5:42 ` [PATCH v3 06/16] ipmi: kcs_bmc: Split headers into device and client Andrew Jeffery
2021-05-21  7:18   ` Zev Weiss
2021-05-10  5:42 ` [PATCH v3 07/16] ipmi: kcs_bmc: Strip private client data from struct kcs_bmc Andrew Jeffery
2021-05-21  7:18   ` Zev Weiss
2021-05-10  5:42 ` [PATCH v3 08/16] ipmi: kcs_bmc: Decouple the IPMI chardev from the core Andrew Jeffery
2021-05-21  7:19   ` Zev Weiss
2021-05-10  5:42 ` [PATCH v3 09/16] ipmi: kcs_bmc: Allow clients to control KCS IRQ state Andrew Jeffery
2021-05-21  7:19   ` Zev Weiss
2021-05-10  5:42 ` Andrew Jeffery [this message]
2021-05-21 17:30   ` [PATCH v3 10/16] ipmi: kcs_bmc: Don't enforce single-open policy in the kernel Corey Minyard
2021-05-24  0:39     ` Andrew Jeffery
2021-05-10  5:42 ` [PATCH v3 11/16] ipmi: kcs_bmc: Add serio adaptor Andrew Jeffery
2021-05-21  7:20   ` Zev Weiss
2021-06-08  0:37     ` Andrew Jeffery
2021-05-10  5:42 ` [PATCH v3 12/16] dt-bindings: ipmi: Convert ASPEED KCS binding to schema Andrew Jeffery
2021-05-10  5:42 ` [PATCH v3 13/16] dt-bindings: ipmi: Add optional SerIRQ property to ASPEED KCS devices Andrew Jeffery
2021-05-10  5:42 ` [PATCH v3 14/16] ipmi: kcs_bmc_aspeed: Implement KCS SerIRQ configuration Andrew Jeffery
2021-05-21  7:21   ` Zev Weiss
2021-06-08  0:41     ` Andrew Jeffery
2021-06-08  0:55       ` Andrew Jeffery
2021-05-10  5:42 ` [PATCH v3 15/16] ipmi: kcs_bmc_aspeed: Fix IBFIE typo from datasheet Andrew Jeffery
2021-05-10  5:42 ` [PATCH v3 16/16] ipmi: kcs_bmc_aspeed: Optionally apply status address Andrew Jeffery
2021-05-20  6:51 ` [PATCH v3 00/16] ipmi: Allow raw access to KCS devices Andrew Jeffery
2021-05-20 13:33   ` Corey Minyard
2021-05-21 17:36 ` Corey Minyard
2021-05-24  0:36   ` Andrew Jeffery

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