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MIPS: Fix broken malta qemu

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Malta defconfig compiles with GIC on. Hence when compiling for SMP it causes
the new IPI code to be activated. But on qemu malta there's no GIC causing a
BUG_ON(!ipidomain) to be hit in mips_smp_ipi_init().

Since in that configuration one can only run a single core SMP (!), skip IPI
initialisation if we detect that this is the case. It is a sensible
behaviour to introduce and should keep such possible configuration to run
rather than die hard unnecessarily.

Signed-off-by: Qais Yousef <qsyousef@gmail.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12892/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Qais Yousef 2016-03-17 21:08:09 +00:00 committed by Ralf Baechle
parent f55532a0c0
commit 19fb5818ed
1 changed files with 12 additions and 0 deletions
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12
arch/mips/kernel/smp.c
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@ -243,6 +243,18 @@ static int __init mips_smp_ipi_init(void)
struct irq_domain *ipidomain;
struct device_node *node;
/*
* In some cases like qemu-malta, it is desired to try SMP with
* a single core. Qemu-malta has no GIC, so an attempt to set any IPIs
* would cause a BUG_ON() to be triggered since there's no ipidomain.
*
* Since for a single core system IPIs aren't required really, skip the
* initialisation which should generally keep any such configurations
* happy and only fail hard when trying to truely run SMP.
*/
if (cpumask_weight(cpu_possible_mask) == 1)
return 0;
node = of_irq_find_parent(of_root);
ipidomain = irq_find_matching_host(node, DOMAIN_BUS_IPI);