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

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

On Wednesday 19 February 2014 02:27 PM, Kirill Tkhai wrote:
> 
> 
> 19.02.2014, 12:12, "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.
> 
> If tb->active is zero, flush_tsb_user() is never called, because of tlb_nr is permanently zero.
>
Sorry, my bad. tb->active was set to one when I ran the test with the above patch.

- Allen