kexec jump: fix for lockdep

Replace local_irq_disable() with raw_local_irq_disable() to prevent lockdep complain.

Signed-off-by Huang Ying <[email protected]>

---
 arch/x86/kernel/machine_kexec_32.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

arch/x86/kernel/machine_kexec_32.c +1 -2

@@ -123,7 +123,7 @@ void machine_kexec(struct kimage *image)
 	tracer_disable();
 
 	/* Interrupts aren't acceptable while we reboot */
-	local_irq_disable();
+	raw_local_irq_disable();
 
 	if (image->preserve_context) {
 #ifdef CONFIG_X86_IO_APIC
 
 
--

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Quoted 2 lines · Huang Ying

Replace local_irq_disable() with raw_local_irq_disable() to prevent lockdep complain.

Uhhm, please provide more information - just using raw_* to silence lockdep is generally the wrong thing to do.

Quoted 5 lines · Peter Zijlstra

Quoted 2 lines · Huang Ying

Replace local_irq_disable() with raw_local_irq_disable() to prevent lockdep complain.

Uhhm, please provide more information - just using raw_* to silence lockdep is generally the wrong thing to do.

In traditional kexec, the new kernel will replace current one, so the irq is simply disabled. But now jumping back from kexeced kernel is supported, so the irq should be enabled again.

The code sequence of irq during kexec jump is as follow:

local_irq_disable(); /* in kernel_kexec() */
local_irq_disable(); /* in machine_kexec() */
local_irq_enable(); /* in kernel_kexec() */

The disable and enable is not match. Maybe another method is to use local_irq_save(), local_irq_restore() pair in machine_kexec(), so the disable and enable is matched.

Quoted 13 lines · Huang Ying

Quoted 5 lines · Peter Zijlstra

Quoted 2 lines · Huang Ying

Replace local_irq_disable() with raw_local_irq_disable() to prevent lockdep complain.

Uhhm, please provide more information - just using raw_* to silence lockdep is generally the wrong thing to do.

In traditional kexec, the new kernel will replace current one, so the irq is simply disabled. But now jumping back from kexeced kernel is supported, so the irq should be enabled again.

The code sequence of irq during kexec jump is as follow:

Quoted 7 lines

local_irq_disable(); /* in kernel_kexec() */
local_irq_disable(); /* in machine_kexec() */
local_irq_enable(); /* in kernel_kexec() */

The disable and enable is not match. Maybe another method is to use local_irq_save(), local_irq_restore() pair in machine_kexec(), so the disable and enable is matched.

And its the machine kernel's lockdep instance that goes complain?

whichever annotation gets used - and I think I can agree that raw_* might be approriate there, this should be accompanied with a rather elaborate changelog and preferably a comment in the code too. Without such we'll be wondering in the years to come WTH happens here.