[PATCH v2 0/7] Provide and use generic_handle_irq_safe() where appropriate.

[PATCH v2 0/7] Provide and use generic_handle_irq_safe() where appropriate.

[Sebastian Andrzej Siewior]

generic_handle_irq() must be used from primary IRQ-handler (chain
handler/ interrupt controller entry). It is low level code and the
function expects that interrupts are disabled at entry point.

This isn't the case for invocations from tasklets, workqueues or the
primary interrupt handler on PREEMPT_RT. Once this gets noticed a
"local_irq_disable|safe()" is added. To avoid further confusion this
series adds generic_handle_irq_safe() which can be used from any context
and adds a few user.

v2…v1:
 - Redo kernel-doc for generic_handle_irq_safe() in #1.
 - Use generic_handle_irq_safe() instead of generic_handle_irq() in the
   patch description where I accidently used the wrong one.

v1:
   https://lore.kernel.org/all/20220127113303.3012207-1-bigeasy@linutronix.de/

Sebastian

[PATCH v2 1/7] genirq: Provide generic_handle_irq_safe().

[Sebastian Andrzej Siewior]

Provide generic_handle_irq_safe() which can used from any context.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Oleksandr Natalenko <oleksandr@natalenko.name>
---
 include/linux/irqdesc.h |  1 +
 kernel/irq/irqdesc.c    | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 93d270ca0c567..a77584593f7d1 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -160,6 +160,7 @@ static inline void generic_handle_irq_desc(struct irq_desc *desc)
 
 int handle_irq_desc(struct irq_desc *desc);
 int generic_handle_irq(unsigned int irq);
+int generic_handle_irq_safe(unsigned int irq);
 
 #ifdef CONFIG_IRQ_DOMAIN
 /*
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 2267e6527db3c..4c58fa940a61c 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -662,6 +662,29 @@ int generic_handle_irq(unsigned int irq)
 }
 EXPORT_SYMBOL_GPL(generic_handle_irq);
 
+/**
+ * generic_handle_irq_safe - Invoke the handler for a particular irq from any
+ *			     context.
+ * @irq:	The irq number to handle
+ *
+ * Returns:	0 on success, a negative value on error.
+ *
+ * This function can be called any context (IRQ or process context). It will
+ * report an error if not invoked from IRQ context and the irq has been marked
+ * to enforce IRQ-contex only.
+ */
+int generic_handle_irq_safe(unsigned int irq)
+{
+	unsigned long flags;
+	int ret;
+
+	local_irq_save(flags);
+	ret = handle_irq_desc(irq_to_desc(irq));
+	local_irq_restore(flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(generic_handle_irq_safe);
+
 #ifdef CONFIG_IRQ_DOMAIN
 /**
  * generic_handle_domain_irq - Invoke the handler for a HW irq belonging
-- 
2.34.1

[PATCH v2 2/7] i2c: core: Use generic_handle_irq_safe() in i2c_handle_smbus_host_notify().

[Sebastian Andrzej Siewior]

The i2c-i801 driver invokes i2c_handle_smbus_host_notify() from his
interrupt service routine. On PREEMPT_RT i2c-i801's handler is forced
threaded with enabled interrupts which leads to a warning by
handle_irq_event_percpu() assuming that irq_default_primary_handler()
enabled interrupts.

i2c-i801's interrupt handler can't be made non-threaded because the
interrupt line is shared with other devices.

Use generic_handle_irq_safe() which can invoked with disabled and enabled
interrupts.

Reported-by: Michael Below <below@judiz.de>
Link: https://bugs.debian.org/1002537
Cc: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Acked-by: Wolfram Sang <wsa@kernel.org>
---
 drivers/i2c/i2c-core-base.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 2c59dd748a49f..3f9e5303b6163 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1424,7 +1424,7 @@ int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr)
 	if (irq <= 0)
 		return -ENXIO;
 
-	generic_handle_irq(irq);
+	generic_handle_irq_safe(irq);
 
 	return 0;
 }
-- 
2.34.1

[PATCH v2 3/7] i2c: cht-wc: Use generic_handle_irq_safe().

[Sebastian Andrzej Siewior]

Instead of manually disabling interrupts before invoking use
generic_handle_irq_safe() which can be invoked with enabled and disabled
interrupts.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Wolfram Sang <wsa@kernel.org>
---
 drivers/i2c/busses/i2c-cht-wc.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/i2c/busses/i2c-cht-wc.c b/drivers/i2c/busses/i2c-cht-wc.c
index 1cf68f85b2e11..8ccf0c928bb44 100644
--- a/drivers/i2c/busses/i2c-cht-wc.c
+++ b/drivers/i2c/busses/i2c-cht-wc.c
@@ -99,15 +99,8 @@ static irqreturn_t cht_wc_i2c_adap_thread_handler(int id, void *data)
 	 * interrupt handler as well, so running the client irq handler from
 	 * this thread will cause things to lock up.
 	 */
-	if (reg & CHT_WC_EXTCHGRIRQ_CLIENT_IRQ) {
-		/*
-		 * generic_handle_irq expects local IRQs to be disabled
-		 * as normally it is called from interrupt context.
-		 */
-		local_irq_disable();
-		generic_handle_irq(adap->client_irq);
-		local_irq_enable();
-	}
+	if (reg & CHT_WC_EXTCHGRIRQ_CLIENT_IRQ)
+		generic_handle_irq_safe(adap->client_irq);
 
 	return IRQ_HANDLED;
 }
-- 
2.34.1

[PATCH v2 4/7] mfd: hi6421-spmi-pmic: Use generic_handle_irq_safe().

[Sebastian Andrzej Siewior]

generic_handle_irq() is invoked from a regular interrupt service
routine. This handler will become a forced-threaded handler on
PREEMPT_RT and will be invoked with enabled interrupts. The
generic_handle_irq() must be invoked with disabled interrupts in order
to avoid deadlocks.

Instead of manually disabling interrupts before invoking use
generic_handle_irq_safe() which can be invoked with enabled and disabled
interrupts.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/misc/hi6421v600-irq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/hi6421v600-irq.c b/drivers/misc/hi6421v600-irq.c
index 1c763796cf1fa..caa3de37698b0 100644
--- a/drivers/misc/hi6421v600-irq.c
+++ b/drivers/misc/hi6421v600-irq.c
@@ -117,8 +117,8 @@ static irqreturn_t hi6421v600_irq_handler(int irq, void *__priv)
 			 * If both powerkey down and up IRQs are received,
 			 * handle them at the right order
 			 */
-			generic_handle_irq(priv->irqs[POWERKEY_DOWN]);
-			generic_handle_irq(priv->irqs[POWERKEY_UP]);
+			generic_handle_irq_safe(priv->irqs[POWERKEY_DOWN]);
+			generic_handle_irq_safe(priv->irqs[POWERKEY_UP]);
 			pending &= ~HISI_IRQ_POWERKEY_UP_DOWN;
 		}
 
@@ -126,7 +126,7 @@ static irqreturn_t hi6421v600_irq_handler(int irq, void *__priv)
 			continue;
 
 		for_each_set_bit(offset, &pending, BITS_PER_BYTE) {
-			generic_handle_irq(priv->irqs[offset + i * BITS_PER_BYTE]);
+			generic_handle_irq_safe(priv->irqs[offset + i * BITS_PER_BYTE]);
 		}
 	}
 
-- 
2.34.1

[PATCH v2 5/7] mfd: ezx-pcap: Use generic_handle_irq_safe().

[Sebastian Andrzej Siewior]

Instead of manually disabling interrupts before invoking use
generic_handle_irq_safe() which can be invoked with enabled and disabled
interrupts.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/mfd/ezx-pcap.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/mfd/ezx-pcap.c b/drivers/mfd/ezx-pcap.c
index 70fa18b04ad2b..b14d3f98e1ebd 100644
--- a/drivers/mfd/ezx-pcap.c
+++ b/drivers/mfd/ezx-pcap.c
@@ -193,13 +193,11 @@ static void pcap_isr_work(struct work_struct *work)
 		ezx_pcap_write(pcap, PCAP_REG_MSR, isr | msr);
 		ezx_pcap_write(pcap, PCAP_REG_ISR, isr);
 
-		local_irq_disable();
 		service = isr & ~msr;
 		for (irq = pcap->irq_base; service; service >>= 1, irq++) {
 			if (service & 1)
-				generic_handle_irq(irq);
+				generic_handle_irq_safe(irq);
 		}
-		local_irq_enable();
 		ezx_pcap_write(pcap, PCAP_REG_MSR, pcap->msr);
 	} while (gpio_get_value(pdata->gpio));
 }
-- 
2.34.1

[PATCH v2 6/7] net: usb: lan78xx: Use generic_handle_irq_safe().

[Sebastian Andrzej Siewior]

Instead of manually disabling interrupts before invoking use
generic_handle_irq_safe() which can be invoked with enabled and disabled
interrupts.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/net/usb/lan78xx.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index b8e20a3f2b84e..415f16662f88e 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -1537,11 +1537,8 @@ static void lan78xx_status(struct lan78xx_net *dev, struct urb *urb)
 		netif_dbg(dev, link, dev->net, "PHY INTR: 0x%08x\n", intdata);
 		lan78xx_defer_kevent(dev, EVENT_LINK_RESET);
 
-		if (dev->domain_data.phyirq > 0) {
-			local_irq_disable();
-			generic_handle_irq(dev->domain_data.phyirq);
-			local_irq_enable();
-		}
+		if (dev->domain_data.phyirq > 0)
+			generic_handle_irq_safe(dev->domain_data.phyirq);
 	} else {
 		netdev_warn(dev->net,
 			    "unexpected interrupt: 0x%08x\n", intdata);
-- 
2.34.1

[PATCH v2 7/7] staging: greybus: gpio: Use generic_handle_irq_safe().

[Sebastian Andrzej Siewior]

Instead of manually disabling interrupts before invoking use
generic_handle_irq_safe() which can be invoked with enabled and disabled
interrupts.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/staging/greybus/gpio.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/staging/greybus/gpio.c b/drivers/staging/greybus/gpio.c
index 7e6347fe93f99..8a7cf1d0e9688 100644
--- a/drivers/staging/greybus/gpio.c
+++ b/drivers/staging/greybus/gpio.c
@@ -391,10 +391,7 @@ static int gb_gpio_request_handler(struct gb_operation *op)
 		return -EINVAL;
 	}
 
-	local_irq_disable();
-	ret = generic_handle_irq(irq);
-	local_irq_enable();
-
+	ret = generic_handle_irq_safe(irq);
 	if (ret)
 		dev_err(dev, "failed to invoke irq handler\n");
 
-- 
2.34.1

Re: [PATCH v2 7/7] staging: greybus: gpio: Use generic_handle_irq_safe().

[Greg Kroah-Hartman]

On Mon, Jan 31, 2022 at 01:34:04PM +0100, Sebastian Andrzej Siewior wrote:
> Instead of manually disabling interrupts before invoking use
> generic_handle_irq_safe() which can be invoked with enabled and disabled
> interrupts.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [PATCH v2 4/7] mfd: hi6421-spmi-pmic: Use generic_handle_irq_safe().

[Lee Jones]

On Mon, 31 Jan 2022, Sebastian Andrzej Siewior wrote:

> generic_handle_irq() is invoked from a regular interrupt service
> routine. This handler will become a forced-threaded handler on
> PREEMPT_RT and will be invoked with enabled interrupts. The
> generic_handle_irq() must be invoked with disabled interrupts in order
> to avoid deadlocks.
> 
> Instead of manually disabling interrupts before invoking use
> generic_handle_irq_safe() which can be invoked with enabled and disabled
> interrupts.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  drivers/misc/hi6421v600-irq.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

The subject line should be "misc".

> diff --git a/drivers/misc/hi6421v600-irq.c b/drivers/misc/hi6421v600-irq.c
> index 1c763796cf1fa..caa3de37698b0 100644
> --- a/drivers/misc/hi6421v600-irq.c
> +++ b/drivers/misc/hi6421v600-irq.c
> @@ -117,8 +117,8 @@ static irqreturn_t hi6421v600_irq_handler(int irq, void *__priv)
>  			 * If both powerkey down and up IRQs are received,
>  			 * handle them at the right order
>  			 */
> -			generic_handle_irq(priv->irqs[POWERKEY_DOWN]);
> -			generic_handle_irq(priv->irqs[POWERKEY_UP]);
> +			generic_handle_irq_safe(priv->irqs[POWERKEY_DOWN]);
> +			generic_handle_irq_safe(priv->irqs[POWERKEY_UP]);
>  			pending &= ~HISI_IRQ_POWERKEY_UP_DOWN;
>  		}
>  
> @@ -126,7 +126,7 @@ static irqreturn_t hi6421v600_irq_handler(int irq, void *__priv)
>  			continue;
>  
>  		for_each_set_bit(offset, &pending, BITS_PER_BYTE) {
> -			generic_handle_irq(priv->irqs[offset + i * BITS_PER_BYTE]);
> +			generic_handle_irq_safe(priv->irqs[offset + i * BITS_PER_BYTE]);
>  		}
>  	}
>  

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH v2 7/7] staging: greybus: gpio: Use generic_handle_irq_safe().

[Johan Hovold]

On Mon, Jan 31, 2022 at 01:34:04PM +0100, Sebastian Andrzej Siewior wrote:
> Instead of manually disabling interrupts before invoking use
> generic_handle_irq_safe() which can be invoked with enabled and disabled
> interrupts.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Acked-by: Johan Hovold <johan@kernel.org>

[PATCH v2.1 4/7] misc: hi6421-spmi-pmic: Use generic_handle_irq_safe().

[Sebastian Andrzej Siewior]

generic_handle_irq() is invoked from a regular interrupt service
routine. This handler will become a forced-threaded handler on
PREEMPT_RT and will be invoked with enabled interrupts. The
generic_handle_irq() must be invoked with disabled interrupts in order
to avoid deadlocks.

Instead of manually disabling interrupts before invoking use
generic_handle_irq_safe() which can be invoked with enabled and disabled
interrupts.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/misc/hi6421v600-irq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/hi6421v600-irq.c b/drivers/misc/hi6421v600-irq.c
index 1c763796cf1fa..caa3de37698b0 100644
--- a/drivers/misc/hi6421v600-irq.c
+++ b/drivers/misc/hi6421v600-irq.c
@@ -117,8 +117,8 @@ static irqreturn_t hi6421v600_irq_handler(int irq, void *__priv)
 			 * If both powerkey down and up IRQs are received,
 			 * handle them at the right order
 			 */
-			generic_handle_irq(priv->irqs[POWERKEY_DOWN]);
-			generic_handle_irq(priv->irqs[POWERKEY_UP]);
+			generic_handle_irq_safe(priv->irqs[POWERKEY_DOWN]);
+			generic_handle_irq_safe(priv->irqs[POWERKEY_UP]);
 			pending &= ~HISI_IRQ_POWERKEY_UP_DOWN;
 		}
 
@@ -126,7 +126,7 @@ static irqreturn_t hi6421v600_irq_handler(int irq, void *__priv)
 			continue;
 
 		for_each_set_bit(offset, &pending, BITS_PER_BYTE) {
-			generic_handle_irq(priv->irqs[offset + i * BITS_PER_BYTE]);
+			generic_handle_irq_safe(priv->irqs[offset + i * BITS_PER_BYTE]);
 		}
 	}
 
-- 
2.34.1

Re: [PATCH v2 1/7] genirq: Provide generic_handle_irq_safe().

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 393 bytes --]


> + * This function can be called any context (IRQ or process context). It will

"from any context"

> + * report an error if not invoked from IRQ context and the irq has been marked
> + * to enforce IRQ-contex only.

"IRQ-context"

Other than that, the paragraph is really helpful now IMO. So with the
above fixed, you may add:

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[PATCH v3 1/7] genirq: Provide generic_handle_irq_safe().

[Sebastian Andrzej Siewior]

Provide generic_handle_irq_safe() which can used from any context.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

v2…v3: Correct kernel doc for generic_handle_irq_safe() as per Wolfram
       Sang.

 include/linux/irqdesc.h |  1 +
 kernel/irq/irqdesc.c    | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 93d270ca0c567..a77584593f7d1 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -160,6 +160,7 @@ static inline void generic_handle_irq_desc(struct irq_desc *desc)
 
 int handle_irq_desc(struct irq_desc *desc);
 int generic_handle_irq(unsigned int irq);
+int generic_handle_irq_safe(unsigned int irq);
 
 #ifdef CONFIG_IRQ_DOMAIN
 /*
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 2267e6527db3c..346d283d2da14 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -662,6 +662,29 @@ int generic_handle_irq(unsigned int irq)
 }
 EXPORT_SYMBOL_GPL(generic_handle_irq);
 
+/**
+ * generic_handle_irq_safe - Invoke the handler for a particular irq from any
+ *			     context.
+ * @irq:	The irq number to handle
+ *
+ * Returns:	0 on success, a negative value on error.
+ *
+ * This function can be called from any context (IRQ or process context). It
+ * will report an error if not invoked from IRQ context and the irq has been
+ * marked to enforce IRQ-context only.
+ */
+int generic_handle_irq_safe(unsigned int irq)
+{
+	unsigned long flags;
+	int ret;
+
+	local_irq_save(flags);
+	ret = handle_irq_desc(irq_to_desc(irq));
+	local_irq_restore(flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(generic_handle_irq_safe);
+
 #ifdef CONFIG_IRQ_DOMAIN
 /**
  * generic_handle_domain_irq - Invoke the handler for a HW irq belonging
-- 
2.34.1