ACK: [PATCH 1/1] tty/hvc: Use IRQF_SHARED for OPAL hvc consoles
Stefan Bader
stefan.bader at canonical.com
Fri Aug 18 12:48:44 UTC 2017
On 18.08.2017 14:22, Colin King wrote:
> From: Sam Mendoza-Jonas <sam at mendozajonas.com>
>
> BugLink: http://bugs.launchpad.net/bugs/1711401
>
> Commit 2def86a7200c ("hvc: Convert to using interrupts instead of opal
> events") enabled the use of interrupts in the hvc_driver for OPAL
> platforms. However on machines with more than one hvc console, any
> console after the first will fail to register an interrupt handler in
> notifier_add_irq() since all consoles share the same IRQ number but do
> not set the IRQF_SHARED flag:
>
> genirq: Flags mismatch irq 31. 00000000 (hvc_console) vs. 00000000 (hvc_console)
> hvc_open: request_irq failed with rc -16.
>
> This error propagates up to hvc_open() and the console is closed, but
> OPAL will still generate interrupts that are not handled, leading to
> rcu_sched stall warnings.
>
> Set IRQF_SHARED when calling request_irq(), allowing additional consoles
> to start properly. This is only set for consoles handled by
> hvc_opal_probe(), leaving other types unaffected.
>
> Signed-off-by: Samuel Mendoza-Jonas <sam at mendozajonas.com>
> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
> (upstream cherry-pick of commit bbc3dfe8805de86874b1a1b1429a002e8670043e)
> Signed-off-by: Colin Ian King <colin.king at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
> ---
> drivers/tty/hvc/hvc_console.h | 1 +
> drivers/tty/hvc/hvc_irq.c | 9 +++++++--
> drivers/tty/hvc/hvc_opal.c | 3 +++
> 3 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/hvc/hvc_console.h b/drivers/tty/hvc/hvc_console.h
> index 913101980827..798c48d0d32c 100644
> --- a/drivers/tty/hvc/hvc_console.h
> +++ b/drivers/tty/hvc/hvc_console.h
> @@ -60,6 +60,7 @@ struct hvc_struct {
> struct winsize ws;
> struct work_struct tty_resize;
> struct list_head next;
> + unsigned long flags;
> };
>
> /* implemented by a low level driver */
> diff --git a/drivers/tty/hvc/hvc_irq.c b/drivers/tty/hvc/hvc_irq.c
> index c9adb0559f61..bc7a96874637 100644
> --- a/drivers/tty/hvc/hvc_irq.c
> +++ b/drivers/tty/hvc/hvc_irq.c
> @@ -14,6 +14,11 @@ static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance)
> /* if hvc_poll request a repoll, then kick the hvcd thread */
> if (hvc_poll(dev_instance))
> hvc_kick();
> +
> + /*
> + * We're safe to always return IRQ_HANDLED as the hvcd thread will
> + * iterate through each hvc_struct.
> + */
> return IRQ_HANDLED;
> }
>
> @@ -28,8 +33,8 @@ int notifier_add_irq(struct hvc_struct *hp, int irq)
> hp->irq_requested = 0;
> return 0;
> }
> - rc = request_irq(irq, hvc_handle_interrupt, 0,
> - "hvc_console", hp);
> + rc = request_irq(irq, hvc_handle_interrupt, hp->flags,
> + "hvc_console", hp);
> if (!rc)
> hp->irq_requested = 1;
> return rc;
> diff --git a/drivers/tty/hvc/hvc_opal.c b/drivers/tty/hvc/hvc_opal.c
> index 47b54c6aefd2..b7cd0ae7d927 100644
> --- a/drivers/tty/hvc/hvc_opal.c
> +++ b/drivers/tty/hvc/hvc_opal.c
> @@ -224,6 +224,9 @@ static int hvc_opal_probe(struct platform_device *dev)
> hp = hvc_alloc(termno, irq, ops, MAX_VIO_PUT_CHARS);
> if (IS_ERR(hp))
> return PTR_ERR(hp);
> +
> + /* hvc consoles on powernv may need to share a single irq */
> + hp->flags = IRQF_SHARED;
> dev_set_drvdata(&dev->dev, hp);
>
> return 0;
>
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