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Commit 30e1e6d1 authored by Rusty Russell's avatar Rusty Russell Committed by Ingo Molnar
Browse files

cpumask: fix CONFIG_CPUMASK_OFFSTACK=y cpu hotunplug crash 



Impact: Fix cpu offline when CONFIG_MAXSMP=y

Changeset bc9b83dd "cpumask: convert
c1e_mask in arch/x86/kernel/process.c to cpumask_var_t" contained a
bug: c1e_mask is manipulated even if C1E isn't detected (and hence
not allocated).

This is simply fixed by checking for NULL (which gcc optimizes out
anyway of CONFIG_CPUMASK_OFFSTACK=n, since it knows ce1_mask can never
be NULL).

In addition, fix a leak where select_idle_routine re-allocates
(and re-clears) c1e_mask on every cpu init.

Reported-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Cc: Mike Travis <travis@sgi.com>
LKML-Reference: <200903171450.34549.rusty@rustcorp.com.au>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 082edb7b

arch/x86/include/asm/processor.h

+1 −0
Original line number Diff line number Diff line
@@ -733,6 +733,7 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx) 
extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);



extern void select_idle_routine(const struct cpuinfo_x86 *c);

extern void init_c1e_mask(void);



extern unsigned long		boot_option_idle_override;

extern unsigned long		idle_halt;

arch/x86/kernel/cpu/common.c

+1 −0
Original line number Diff line number Diff line
@@ -812,6 +812,7 @@ static void vgetcpu_set_mode(void) 
void __init identify_boot_cpu(void)

{

	identify_cpu(&boot_cpu_data);

	init_c1e_mask();

#ifdef CONFIG_X86_32

	sysenter_setup();

	enable_sep_cpu();

arch/x86/kernel/process.c

+11 −3
Original line number Diff line number Diff line
@@ -479,6 +479,7 @@ static int c1e_detected; 


void c1e_remove_cpu(int cpu)

{

	if (c1e_mask != NULL)

		cpumask_clear_cpu(cpu, c1e_mask);

}
@@ -556,13 +557,20 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) 
		pm_idle = mwait_idle;

	} else if (check_c1e_idle(c)) {

		printk(KERN_INFO "using C1E aware idle routine\n");

		alloc_cpumask_var(&c1e_mask, GFP_KERNEL);

		cpumask_clear(c1e_mask);

		pm_idle = c1e_idle;

	} else

		pm_idle = default_idle;

}



void __init init_c1e_mask(void)

{

	/* If we're using c1e_idle, we need to allocate c1e_mask. */

	if (pm_idle == c1e_idle) {

		alloc_cpumask_var(&c1e_mask, GFP_KERNEL);

		cpumask_clear(c1e_mask);

	}

}



static int __init idle_setup(char *str)

{

	if (!str)