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: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110120110635.GB6036@htj.dyndns.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 7e8d3bc80af6969b5ae5e1a35ab15463000fd7eb..50542efe45fbbc9313e8d66670d99ce573d682a6 100644 (file)
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -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();
 

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 5a9d9059520b9fd36fb4049bef4e673a18a9cdd1..d07d8057e440e9eb685b0ab36d9f29cd64db97d5 100644 (file)
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -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,

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 71c09b26c7592ff4a1f6351fd226c9442ef66e5d..f638fd78d106cff2d2e91c3a9d141017fb1aa764 100644 (file)
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -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)
 {
 }

diff --git a/init/main.c b/init/main.c
index 00799c1d46288fb491e6eb07ccf17dc8406883cc..33c37c379e96458521a0111a968849139edcf586 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -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. */

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 42ba65dff7d99e4eeadfe6175d70c2f9665ad431..0d2058da80f51888b503f4e92829bddbe884b264 100644 (file)
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -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)) {

diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 5cf8c602b8804c054bbed65475b4815fd29d5b82..92b6e1e12d982931309e4ecf431a923ffff56c84 100644 (file)
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -453,14 +453,6 @@ void time_hardirqs_off(unsigned long a0, unsigned long a1)
  * Stubs:
  */
 
-void early_boot_irqs_off(void)
-{
-}
-
-void early_boot_irqs_on(void)
-{
-}
-
 void trace_softirqs_on(unsigned long ip)
 {
 }