Re: [PATCH] tty/hvc: Use IRQF_SHARED for hvc consoles

From: Stewart Smith
Date: Wed Mar 23 2016 - 01:18:26 EST

Samuel Mendoza-Jonas <sam@xxxxxxxxxxxxxxxx> writes:
> 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:
> [ 51.179907] genirq: Flags mismatch irq 31. 00000000 (hvc_console) vs.
> 00000000 (hvc_console)
> [ 51.180010] 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.
> Signed-off-by: Samuel Mendoza-Jonas <sam@xxxxxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # 4.1.x-

Tested on 4.4.6 - seemed to stop (some of) the problems I was having
when using it as a kernel for the bootloader on a FSP based POWER8

Tested-by: Stewart Smith <stewart@xxxxxxxxxxxxxxxxxx>

Stewart Smith
OPAL Architect, IBM.