Commit 2ce802f6 authored by Tejun Heo's avatar Tejun Heo Committed by Ingo Molnar
Browse files

lockdep: Move early boot local IRQ enable/disable status to init/main.c 



During early boot, local IRQ is disabled until IRQ subsystem is
properly initialized.  During this time, no one should enable
local IRQ and some operations which usually are not allowed with
IRQ disabled, e.g. operations which might sleep or require
communications with other processors, are allowed.

lockdep tracked this with early_boot_irqs_off/on() callbacks.
As other subsystems need this information too, move it to
init/main.c and make it generally available.  While at it,
toggle the boolean to early_boot_irqs_disabled instead of
enabled so that it can be initialized with %false and %true
indicates the exceptional condition.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarPekka Enberg <penberg@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110120110635.GB6036@htj.dyndns.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 12fcdba1

arch/x86/xen/enlighten.c

+1 −1
Original line number Diff line number Diff line
@@ -1194,7 +1194,7 @@ asmlinkage void __init xen_start_kernel(void) 
	per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];



	local_irq_disable();

	early_boot_irqs_off();

	early_boot_irqs_disabled = true;



	memblock_init();

include/linux/kernel.h

+2 −0
Original line number Diff line number Diff line
@@ -243,6 +243,8 @@ extern int test_taint(unsigned flag); 
extern unsigned long get_taint(void);

extern int root_mountflags;



extern bool early_boot_irqs_disabled;



/* Values used for system_state */

extern enum system_states {

	SYSTEM_BOOTING,

include/linux/lockdep.h

+0 −8
Original line number Diff line number Diff line
@@ -436,16 +436,8 @@ do { \ 
#endif /* CONFIG_LOCKDEP */



#ifdef CONFIG_TRACE_IRQFLAGS

extern void early_boot_irqs_off(void);

extern void early_boot_irqs_on(void);

extern void print_irqtrace_events(struct task_struct *curr);

#else

static inline void early_boot_irqs_off(void)

{

}

static inline void early_boot_irqs_on(void)

{

}

static inline void print_irqtrace_events(struct task_struct *curr)

{

}

init/main.c

+11 −2
Original line number Diff line number Diff line
@@ -96,6 +96,15 @@ static inline void mark_rodata_ro(void) { } 
extern void tc_init(void);

#endif



/*

 * Debug helper: via this flag we know that we are in 'early bootup code'

 * where only the boot processor is running with IRQ disabled.  This means

 * two things - IRQ must not be enabled before the flag is cleared and some

 * operations which are not allowed with IRQ disabled are allowed while the

 * flag is set.

 */

bool early_boot_irqs_disabled __read_mostly;



enum system_states system_state __read_mostly;

EXPORT_SYMBOL(system_state);
@@ -554,7 +563,7 @@ asmlinkage void __init start_kernel(void) 
	cgroup_init_early();



	local_irq_disable();

	early_boot_irqs_off();

	early_boot_irqs_disabled = true;



/*

 * Interrupts are still disabled. Do necessary setups, then
@@ -621,7 +630,7 @@ asmlinkage void __init start_kernel(void) 
	if (!irqs_disabled())

		printk(KERN_CRIT "start_kernel(): bug: interrupts were "

				 "enabled early\n");

	early_boot_irqs_on();

	early_boot_irqs_disabled = false;

	local_irq_enable();



	/* Interrupts are enabled now so all GFP allocations are safe. */

kernel/lockdep.c

+1 −17
Original line number Diff line number Diff line
@@ -2291,22 +2291,6 @@ mark_held_locks(struct task_struct *curr, enum mark_type mark) 
	return 1;

}



/*

 * Debugging helper: via this flag we know that we are in

 * 'early bootup code', and will warn about any invalid irqs-on event:

 */

static int early_boot_irqs_enabled;



void early_boot_irqs_off(void)

{

	early_boot_irqs_enabled = 0;

}



void early_boot_irqs_on(void)

{

	early_boot_irqs_enabled = 1;

}



/*

 * Hardirqs will be enabled:

 */
@@ -2319,7 +2303,7 @@ void trace_hardirqs_on_caller(unsigned long ip) 
	if (unlikely(!debug_locks || current->lockdep_recursion))

		return;



	if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))

	if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))

		return;



	if (unlikely(curr->hardirqs_enabled)) {

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