linux-kernel - Re: [PATCH] tty/hvc: Use IRQF

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Message-ID: <87twjxydq3.fsf@birb.au.ibm.com>
Date:	Wed, 23 Mar 2016 16:17:56 +1100
From:	Stewart Smith <stewart@...ux.vnet.ibm.com>
To:	Samuel Mendoza-Jonas <sam@...dozajonas.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Samuel Mendoza-Jonas <sam@...dozajonas.com>,
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	Jiri Slaby <jslaby@...e.com>
Subject: Re: [PATCH] tty/hvc: Use IRQF_SHARED for hvc consoles

Samuel Mendoza-Jonas <sam@...dozajonas.com> 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@...dozajonas.com>
> Cc: <stable@...r.kernel.org> # 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
system.

Tested-by: Stewart Smith <stewart@...ux.vnet.ibm.com>

-- 
Stewart Smith
OPAL Architect, IBM.