Re: [PATCH 3/4] sparc64: convert spinlock_t to raw_spinlock_t in mmu_context_t

[Allen Pais <allen.pais@oracle.com>]

>> diff --git a/arch/sparc/mm/tsb.c b/arch/sparc/mm/tsb.c
>> index 9eb10b4..24dcd29 100644
>> --- a/arch/sparc/mm/tsb.c
>> +++ b/arch/sparc/mm/tsb.c
>> @@ -6,6 +6,7 @@
>>  #include <linux/kernel.h>
>>  #include <linux/preempt.h>
>>  #include <linux/slab.h>
>> +#include <linux/locallock.h>
>>  #include <asm/page.h>
>>  #include <asm/pgtable.h>
>>  #include <asm/mmu_context.h>
>> @@ -14,6 +15,7 @@
>>  #include <asm/oplib.h>
>>
>>  extern struct tsb swapper_tsb[KERNEL_TSB_NENTRIES];
>> +static DEFINE_LOCAL_IRQ_LOCK(tsb_lock);
>>
>>  static inline unsigned long tsb_hash(unsigned long vaddr, unsigned long hash_sh
>>  {
>> @@ -71,9 +73,9 @@ static void __flush_tsb_one(struct tlb_batch *tb, unsigned lon
>>  void flush_tsb_user(struct tlb_batch *tb)
>>  {
>>         struct mm_struct *mm = tb->mm;
>> -       unsigned long nentries, base, flags;
>> +       unsigned long nentries, base;
>>
>> -       raw_spin_lock_irqsave(&mm->context.lock, flags);
>> +       local_lock(tsb_lock);
>>
>>         base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
>>         nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
>> @@ -90,7 +92,7 @@ void flush_tsb_user(struct tlb_batch *tb)
>>                 __flush_tsb_one(tb, HPAGE_SHIFT, base, nentries);
>>         }
>>  #endif
>> -       raw_spin_unlock_irqrestore(&mm->context.lock, flags);
>> +       local_unlock(tsb_lock);
> 
> It seems to be not good for me. Tsb setup is in tsb_grow() and it must
> be synchronized with flushing. Flushing is also being made in flush_tsb_user_page()..
> 
> Which last stack stack has you received with tb->active, permanently set to zero?
> 

I agree with you point about flushing in flush_tbs_user_page too. Like i said, this is
a bit tricky to actually debug.

Yes, tb->active was set to zero.

- Allen