Re: [PATCH 6/8] x86: use flush_tlb_others to implement flush_tlb_all

Ian Campbell
2009-05-08T15:52:22Z

On Fri, 2009-05-08 at 11:49 -0400, Jeremy Fitzhardinge wrote:
> Ian Campbell wrote:
> > On Thu, 2009-05-07 at 13:25 -0700, Jeremy Fitzhardinge wrote:
> >
> >> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> >>
> >> Use the flush_tlb_others() call to implement flush_tlb_all().
> >>
> >
> > This causes:
> > BUG: spinlock bad magic on CPU#0, swapper/0
> > lock: c05b7588, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
> > Pid: 0, comm: swapper Not tainted 2.6.30-rc3-x86_32p-xen0-tip-01797-g3db7847 #1054
> > Call Trace:
> > [<c023e656>] spin_bug+0x96/0xf0
> > [<c023e90f>] _raw_spin_lock+0x6f/0x150
> >
>
> Ah, right. I had another change (somewhere around here) to explicitly
> initialize the tlb flush code from the normal early init code, rather
> than make it implicit via initcall. Otherwise we have an unknown point
> at which we're allowed to start using global flushes, which is a bit flakey.

That was my v1, which I still happen to have lying around:

---

Subject: initialise tlbflush locks before any callers

Now that flush_tlb_all() is implemented via flush_tlb_others() the later
can be called before the core_initcalls are run. Explicitly call
init_smp_flush early on.

Also there is no need for init_smp_flush to be __cpuinit.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

[ Impact: initialise spinlock before use ]

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 16a5c84..2a4848d 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -129,6 +129,8 @@ static inline void reset_lazy_tlbstate(void)

#define local_flush_tlb() __flush_tlb()

+extern int init_smp_flush(void);
+
extern void flush_tlb_all(void);
extern void flush_tlb_current_task(void);
extern void flush_tlb_mm(struct mm_struct *);
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index e69bdad..0f030fb 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -229,7 +229,7 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
flush_tlb_others_ipi(cpumask, mm, va);
}

-static int __cpuinit init_smp_flush(void)
+int __init init_smp_flush(void)
{
int i;

@@ -238,7 +238,6 @@ static int __cpuinit init_smp_flush(void)

return 0;
}
-core_initcall(init_smp_flush);

void flush_tlb_current_task(void)
{
diff --git a/init/main.c b/init/main.c
index 33ce929..f798501 100644
--- a/init/main.c
+++ b/init/main.c
@@ -651,6 +651,7 @@ asmlinkage void __init start_kernel(void)
vfs_caches_init_early();
cpuset_init_early();
page_cgroup_init();
+ init_smp_flush();
mem_init();
enable_debug_pagealloc();
cpu_hotplug_init();

>
> J