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x86, cpu hotplug: Fix stack frame warning in check_irq_vectors_for_cp…
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…u_disable()

Further discussion here: http://marc.info/?l=linux-kernel&m=139073901101034&w=2

kbuild, 0day kernel build service, outputs the warning:

arch/x86/kernel/irq.c:333:1: warning: the frame size of 2056 bytes
is larger than 2048 bytes [-Wframe-larger-than=]

because check_irq_vectors_for_cpu_disable() allocates two cpumasks on the
stack.   Fix this by moving the two cpumasks to a global file context.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Tested-by: David Rientjes <rientjes@google.com>
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1390915331-27375-1-git-send-email-prarit@redhat.com
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Yang Zhang <yang.z.zhang@Intel.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Janet Morgan <janet.morgan@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Ruiv Wang <ruiv.wang@gmail.com>
Cc: Gong Chen <gong.chen@linux.intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Prarit Bhargava authored and H. Peter Anvin committed Jan 31, 2014
1 parent edc6bc7 commit 39424e8
Showing 1 changed file with 8 additions and 1 deletion.
9 changes: 8 additions & 1 deletion arch/x86/kernel/irq.c
Original file line number Diff line number Diff line change
Expand Up @@ -266,6 +266,14 @@ __visible void smp_trace_x86_platform_ipi(struct pt_regs *regs)
EXPORT_SYMBOL_GPL(vector_used_by_percpu_irq);

#ifdef CONFIG_HOTPLUG_CPU

/* These two declarations are only used in check_irq_vectors_for_cpu_disable()
* below, which is protected by stop_machine(). Putting them on the stack
* results in a stack frame overflow. Dynamically allocating could result in a
* failure so declare these two cpumasks as global.
*/
static struct cpumask affinity_new, online_new;

/*
* This cpu is going to be removed and its vectors migrated to the remaining
* online cpus. Check to see if there are enough vectors in the remaining cpus.
Expand All @@ -277,7 +285,6 @@ int check_irq_vectors_for_cpu_disable(void)
unsigned int this_cpu, vector, this_count, count;
struct irq_desc *desc;
struct irq_data *data;
struct cpumask affinity_new, online_new;

this_cpu = smp_processor_id();
cpumask_copy(&online_new, cpu_online_mask);
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