Commit f21afc25 authored Jun 14, 2013 by David Daney Committed by Linus Torvalds Jun 14, 2013

smp.h: Use local_irq_{save,restore}() in !SMP version of on_each_cpu().



Thanks to commit f91eb62f ("init: scream bloody murder if interrupts
are enabled too early"), "bloody murder" is now being screamed.

With a MIPS OCTEON config, we use on_each_cpu() in our
irq_chip.irq_bus_sync_unlock() function.  This gets called in early as a
result of the time_init() call.  Because the !SMP version of
on_each_cpu() unconditionally enables irqs, we get:

    WARNING: at init/main.c:560 start_kernel+0x250/0x410()
    Interrupts were enabled early
    CPU: 0 PID: 0 Comm: swapper Not tainted 3.10.0-rc5-Cavium-Octeon+ #801
    Call Trace:
      show_stack+0x68/0x80
      warn_slowpath_common+0x78/0xb0
      warn_slowpath_fmt+0x38/0x48
      start_kernel+0x250/0x410

Suggested fix: Do what we already do in the SMP version of
on_each_cpu(), and use local_irq_save/local_irq_restore.  Because we
need a flags variable, make it a static inline to avoid name space
issues.

[ Change from v1: Convert on_each_cpu to a static inline function, add
  #include <linux/irqflags.h> to avoid build breakage on some files.

  on_each_cpu_mask() and on_each_cpu_cond() suffer the same problem as
  on_each_cpu(), but they are not causing !SMP bugs for me, so I will
  defer changing them to a less urgent patch. ]

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent d0ff9348

include/linux/smp.h

+12 −7

Original line number	Diff line number	Diff line
		@@ -11,6 +11,7 @@
		#include <linux/list.h>
		#include <linux/cpumask.h>
		#include <linux/init.h>
		#include <linux/irqflags.h>

		extern void cpu_idle(void);

		@@ -139,13 +140,17 @@ static inline int up_smp_call_function(smp_call_func_t func, void *info)
		}
		#define smp_call_function(func, info, wait) \
		(up_smp_call_function(func, info))
		#define on_each_cpu(func,info,wait) \
		({ \
		local_irq_disable(); \
		func(info); \
		local_irq_enable(); \
		0; \
		})

		static inline int on_each_cpu(smp_call_func_t func, void *info, int wait)
		{
		unsigned long flags;

		local_irq_save(flags);
		func(info);
		local_irq_restore(flags);
		return 0;
		}

		/*
		* Note we still need to test the mask even for UP
		* because we actually can get an empty mask from

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