From: Zev Weiss <zweiss@equinix.com>
To: Andrew Jeffery <andrew@aj.id.au>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"chiawei_wang@aspeedtech.com" <chiawei_wang@aspeedtech.com>,
"ryan_chen@aspeedtech.com" <ryan_chen@aspeedtech.com>,
"tmaimon77@gmail.com" <tmaimon77@gmail.com>,
"minyard@acm.org" <minyard@acm.org>,
"avifishman70@gmail.com" <avifishman70@gmail.com>,
"venture@google.com" <venture@google.com>,
"openbmc@lists.ozlabs.org" <openbmc@lists.ozlabs.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"tali.perry1@gmail.com" <tali.perry1@gmail.com>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
"robh+dt@kernel.org" <robh+dt@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"openipmi-developer@lists.sourceforge.net"
<openipmi-developer@lists.sourceforge.net>,
"lee.jones@linaro.org" <lee.jones@linaro.org>,
"linus.walleij@linaro.org" <linus.walleij@linaro.org>,
"linux-aspeed@lists.ozlabs.org" <linux-aspeed@lists.ozlabs.org>,
"benjaminfair@google.com" <benjaminfair@google.com>
Subject: Re: [PATCH v2 15/21] ipmi: kcs_bmc: Don't enforce single-open policy in the kernel
Date: Fri, 9 Apr 2021 05:07:11 +0000 [thread overview]
Message-ID: <YG/g/poZLwO34QH7@packtop> (raw)
In-Reply-To: <20210319062752.145730-15-andrew@aj.id.au>
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 <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 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
>
next prev parent reply other threads:[~2021-04-09 5:09 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-19 6:27 [PATCH v2 01/21] dt-bindings: aspeed-lpc: Remove LPC partitioning Andrew Jeffery
2021-03-19 6:27 ` [PATCH v2 02/21] ARM: dts: Remove LPC BMC and Host partitions Andrew Jeffery
2021-03-19 6:27 ` [PATCH v2 03/21] ipmi: kcs: aspeed: Adapt to new LPC DTS layout Andrew Jeffery
2021-04-09 3:35 ` Joel Stanley
2021-03-19 6:27 ` [PATCH v2 04/21] pinctrl: aspeed-g5: Adapt to new LPC device tree layout Andrew Jeffery
2021-04-09 3:36 ` Joel Stanley
2021-03-19 6:27 ` [PATCH v2 05/21] soc: aspeed: " Andrew Jeffery
2021-04-09 3:38 ` Joel Stanley
2021-03-19 6:27 ` [PATCH v2 06/21] ipmi: kcs_bmc_aspeed: Use of match data to extract KCS properties Andrew Jeffery
2021-04-06 6:07 ` ChiaWei Wang
2021-04-09 3:24 ` Zev Weiss
2021-03-19 6:27 ` [PATCH v2 07/21] ipmi: kcs_bmc: Make status update atomic Andrew Jeffery
2021-04-09 5:32 ` Zev Weiss
2021-03-19 6:27 ` [PATCH v2 08/21] ipmi: kcs_bmc: Rename {read, write}_{status, data}() functions Andrew Jeffery
2021-04-09 5:33 ` Zev Weiss
2021-03-19 6:27 ` [PATCH v2 09/21] ipmi: kcs_bmc: Split out kcs_bmc_cdev_ipmi Andrew Jeffery
2021-04-09 3:56 ` Zev Weiss
2021-04-09 5:48 ` Andrew Jeffery
2021-04-09 19:21 ` Zev Weiss
2021-03-19 6:27 ` [PATCH v2 10/21] ipmi: kcs_bmc: Turn the driver data-structures inside-out Andrew Jeffery
2021-04-09 3:57 ` Zev Weiss
2021-04-09 5:59 ` Andrew Jeffery
2021-04-09 6:25 ` Zev Weiss
2021-04-09 19:26 ` Zev Weiss
2021-04-11 23:00 ` Andrew Jeffery
2021-03-19 6:27 ` [PATCH v2 11/21] ipmi: kcs_bmc: Split headers into device and client Andrew Jeffery
2021-04-09 4:01 ` Zev Weiss
2021-04-09 6:06 ` Andrew Jeffery
2021-03-19 6:27 ` [PATCH v2 12/21] ipmi: kcs_bmc: Strip private client data from struct kcs_bmc Andrew Jeffery
2021-04-09 4:07 ` Zev Weiss
2021-04-09 6:15 ` Andrew Jeffery
2021-03-19 6:27 ` [PATCH v2 13/21] ipmi: kcs_bmc: Decouple the IPMI chardev from the core Andrew Jeffery
2021-04-06 6:07 ` ChiaWei Wang
2021-04-09 4:35 ` Zev Weiss
2021-04-09 6:24 ` Andrew Jeffery
2021-03-19 6:27 ` [PATCH v2 14/21] ipmi: kcs_bmc: Allow clients to control KCS IRQ state Andrew Jeffery
2021-04-09 4:37 ` Zev Weiss
2021-04-09 6:39 ` Andrew Jeffery
2021-03-19 6:27 ` [PATCH v2 15/21] ipmi: kcs_bmc: Don't enforce single-open policy in the kernel Andrew Jeffery
2021-04-09 5:07 ` Zev Weiss [this message]
2021-04-09 6:42 ` Andrew Jeffery
2021-03-19 6:27 ` [PATCH v2 16/21] ipmi: kcs_bmc: Add a "raw" character device interface Andrew Jeffery
2021-04-09 5:17 ` Zev Weiss
2021-04-09 6:46 ` Andrew Jeffery
2021-04-09 7:55 ` Arnd Bergmann
2021-04-12 1:33 ` Andrew Jeffery
2021-04-12 8:48 ` Arnd Bergmann
2021-04-12 23:45 ` Andrew Jeffery
2021-04-13 8:22 ` Arnd Bergmann
2021-04-14 0:30 ` Andrew Jeffery
2021-03-19 6:27 ` [PATCH v2 17/21] dt-bindings: ipmi: Convert ASPEED KCS binding to schema Andrew Jeffery
2021-03-26 1:48 ` Rob Herring
2021-04-09 5:15 ` Zev Weiss
2021-04-09 5:33 ` Andrew Jeffery
2021-04-09 5:44 ` Zev Weiss
2021-04-09 8:46 ` Zev Weiss
2021-03-19 6:27 ` [PATCH v2 18/21] dt-bindings: ipmi: Add optional SerIRQ property to ASPEED KCS devices Andrew Jeffery
2021-03-26 1:49 ` Rob Herring
2021-03-19 6:27 ` [PATCH v2 19/21] ipmi: kcs_bmc_aspeed: Implement KCS SerIRQ configuration Andrew Jeffery
2021-04-01 9:30 ` [EXTERNAL] " Zev Weiss
2021-03-19 6:27 ` [PATCH v2 20/21] ipmi: kcs_bmc_aspeed: Fix IBFIE typo from datasheet Andrew Jeffery
2021-04-09 5:40 ` Zev Weiss
2021-03-19 6:27 ` [PATCH v2 21/21] ipmi: kcs_bmc_aspeed: Optionally apply status address Andrew Jeffery
2021-04-01 18:18 ` Re " Zev Weiss
2021-04-06 6:09 ` ChiaWei Wang
2021-04-09 3:18 ` [PATCH v2 01/21] dt-bindings: aspeed-lpc: Remove LPC partitioning Joel Stanley
2021-04-09 5:24 ` Andrew Jeffery
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