[PATCH] lockdep: annotate i386 apm

Lockdep doesn't like to enable interrupts when they are enabled already.

BUG: warning at kernel/lockdep.c:1814/trace_hardirqs_on() (Not tainted)
 [<c04051ed>] show_trace_log_lvl+0x58/0x16a
 [<c04057fa>] show_trace+0xd/0x10
 [<c0405913>] dump_stack+0x19/0x1b
 [<c043abfb>] trace_hardirqs_on+0xa2/0x11e
 [<c041463c>] apm_bios_call_simple+0xcd/0xfd
 [<c0415242>] apm+0x92/0x5b1
 [<c0402005>] kernel_thread_helper+0x5/0xb
DWARF2 unwinder stuck at kernel_thread_helper+0x5/0xb
Leftover inexact backtrace:
 [<c04057fa>] show_trace+0xd/0x10
 [<c0405913>] dump_stack+0x19/0x1b
 [<c043abfb>] trace_hardirqs_on+0xa2/0x11e
 [<c041463c>] apm_bios_call_simple+0xcd/0xfd
 [<c0415242>] apm+0x92/0x5b1
 [<c0402005>] kernel_thread_helper+0x5/0xb

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/i386/kernel/apm.c

@@ -540,11 +540,30 @@ static inline void apm_restore_cpus(cpumask_t mask)
  * Also, we KNOW that for the non error case of apm_bios_call, there
  * is no useful data returned in the low order 8 bits of eax.
  */
-#define APM_DO_CLI	\
-	if (apm_info.allow_ints) \
-		local_irq_enable(); \
-	else \
+
+static inline unsigned long __apm_irq_save(void)
+{
+	unsigned long flags;
+	local_save_flags(flags);
+	if (apm_info.allow_ints) {
+		if (irqs_disabled_flags(flags))
+			local_irq_enable();
+	} else
+		local_irq_disable();
+
+	return flags;
+}
+
+#define apm_irq_save(flags) \
+	do { flags = __apm_irq_save(); } while (0)
+
+static inline void apm_irq_restore(unsigned long flags)
+{
+	if (irqs_disabled_flags(flags))
 		local_irq_disable();
+	else if (irqs_disabled())
+		local_irq_enable();
+}
 
 #ifdef APM_ZERO_SEGS
 #	define APM_DECL_SEGS \
@@ -596,12 +615,11 @@ static u8 apm_bios_call(u32 func, u32 ebx_in, u32 ecx_in,
 	save_desc_40 = gdt[0x40 / 8];
 	gdt[0x40 / 8] = bad_bios_desc;
 
-	local_save_flags(flags);
-	APM_DO_CLI;
+	apm_irq_save(flags);
 	APM_DO_SAVE_SEGS;
 	apm_bios_call_asm(func, ebx_in, ecx_in, eax, ebx, ecx, edx, esi);
 	APM_DO_RESTORE_SEGS;
-	local_irq_restore(flags);
+	apm_irq_restore(flags);
 	gdt[0x40 / 8] = save_desc_40;
 	put_cpu();
 	apm_restore_cpus(cpus);
@@ -640,12 +658,11 @@ static u8 apm_bios_call_simple(u32 func, u32 ebx_in, u32 ecx_in, u32 *eax)
 	save_desc_40 = gdt[0x40 / 8];
 	gdt[0x40 / 8] = bad_bios_desc;
 
-	local_save_flags(flags);
-	APM_DO_CLI;
+	apm_irq_save(flags);
 	APM_DO_SAVE_SEGS;
 	error = apm_bios_call_simple_asm(func, ebx_in, ecx_in, eax);
 	APM_DO_RESTORE_SEGS;
-	local_irq_restore(flags);
+	apm_irq_restore(flags);
 	gdt[0x40 / 8] = save_desc_40;
 	put_cpu();
 	apm_restore_cpus(cpus);