x86: Call do_notify_resume() with interrupts enabled

do_notify_resume() gets called with interrupts disabled on x86_32. This
is different from the x86_64 behavior, where interrupts are enabled at
the time.

Queries on lkml on this issue hasn't yielded any clear answer. Lets make
x86_32 behave the same as x86_64, unless there is a real reason to
maintain status quo.

Please refer https://lkml.org/lkml/2011/9/27/130 for more
details.

A similar change was suggested in ARM:

	https://lkml.org/lkml/2011/8/25/231

My 32-bit machine works fine (tm) with this patch.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20111025141812.GA21225@linux.vnet.ibm.comSigned-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/entry_32.S

@@ -625,6 +625,8 @@ work_notifysig:				# deal with pending signals and
 	movl %esp, %eax
 	jne work_notifysig_v86		# returning to kernel-space or
 					# vm86-space
+	TRACE_IRQS_ON
+	ENABLE_INTERRUPTS(CLBR_NONE)
 	xorl %edx, %edx
 	call do_notify_resume
 	jmp resume_userspace_sig
@@ -638,6 +640,8 @@ work_notifysig_v86:
 #else
 	movl %esp, %eax
 #endif
+	TRACE_IRQS_ON
+	ENABLE_INTERRUPTS(CLBR_NONE)
 	xorl %edx, %edx
 	call do_notify_resume
 	jmp resume_userspace_sig