Re: [PATCH, RFC] improved hacks to allow -rt to run kernbench on POWER

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> Removed this as well, also seemed to work.  Please note, however, that
> this is just running kernbench.  But this did seem to get rid of some
> of the warnings as well.  ;-)  Now only have the xics_startup() warning.
> 
> > Overall, looks fine !
> 
> I bet that there are more gotchas lurking in there somewhere, but in
> the meantime here is the updated patch.
> 
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---

Well, I suppose the patch could go in, maybe with some ifdef's around
the bits in _switch_to, there's little point in doing that on non-rt
kernels.

Ben.

>  arch/powerpc/kernel/process.c        |   16 ++++++++++++++++
>  arch/powerpc/kernel/prom.c           |    2 +-
>  arch/powerpc/mm/tlb_64.c             |    5 ++++-
>  arch/powerpc/platforms/pseries/eeh.c |    2 +-
>  drivers/of/base.c                    |    2 +-
>  include/asm-powerpc/tlb.h            |    5 ++++-
>  include/asm-powerpc/tlbflush.h       |   15 ++++++++++-----
>  7 files changed, 37 insertions(+), 10 deletions(-)
> 
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/kernel/process.c linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/process.c
> --- linux-2.6.23.1-rt4/arch/powerpc/kernel/process.c	2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/process.c	2007-11-09 13:24:46.000000000 -0800
> @@ -245,6 +245,8 @@ struct task_struct *__switch_to(struct t
>  	struct thread_struct *new_thread, *old_thread;
>  	unsigned long flags;
>  	struct task_struct *last;
> +	struct ppc64_tlb_batch *batch;
> +	int hadbatch;
>  
>  #ifdef CONFIG_SMP
>  	/* avoid complexity of lazy save/restore of fpu
> @@ -325,6 +327,15 @@ struct task_struct *__switch_to(struct t
>  	}
>  #endif
>  
> +	batch = &__get_cpu_var(ppc64_tlb_batch);
> +	if (batch->active) {
> +		hadbatch = 1;
> +		if (batch->index) {
> +			__flush_tlb_pending(batch);
> +		}
> +		batch->active = 0;
> +	}
> +
>  	local_irq_save(flags);
>  
>  	account_system_vtime(current);
> @@ -335,6 +346,11 @@ struct task_struct *__switch_to(struct t
>  
>  	local_irq_restore(flags);
>  
> +	if (hadbatch) {
> +		batch = &__get_cpu_var(ppc64_tlb_batch);
> +		batch->active = 1;
> +	}
> +
>  	return last;
>  }
>  
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/kernel/prom.c linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/prom.c
> --- linux-2.6.23.1-rt4/arch/powerpc/kernel/prom.c	2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/prom.c	2007-10-28 13:37:23.000000000 -0700
> @@ -80,7 +80,7 @@ struct boot_param_header *initial_boot_p
>  
>  extern struct device_node *allnodes;	/* temporary while merging */
>  
> -extern rwlock_t devtree_lock;	/* temporary while merging */
> +extern raw_rwlock_t devtree_lock;	/* temporary while merging */
>  
>  /* export that to outside world */
>  struct device_node *of_chosen;
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/mm/tlb_64.c linux-2.6.23.1-rt4-fix/arch/powerpc/mm/tlb_64.c
> --- linux-2.6.23.1-rt4/arch/powerpc/mm/tlb_64.c	2007-10-27 22:20:57.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/arch/powerpc/mm/tlb_64.c	2007-11-08 16:49:04.000000000 -0800
> @@ -133,7 +133,7 @@ void pgtable_free_tlb(struct mmu_gather 
>  void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
>  		     pte_t *ptep, unsigned long pte, int huge)
>  {
> -	struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
> +	struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
>  	unsigned long vsid, vaddr;
>  	unsigned int psize;
>  	real_pte_t rpte;
> @@ -180,6 +180,7 @@ void hpte_need_flush(struct mm_struct *m
>  	 */
>  	if (!batch->active) {
>  		flush_hash_page(vaddr, rpte, psize, 0);
> +		put_cpu_var(ppc64_tlb_batch);
>  		return;
>  	}
>  
> @@ -212,12 +213,14 @@ void hpte_need_flush(struct mm_struct *m
>  	 */
>  	if (machine_is(celleb)) {
>  		__flush_tlb_pending(batch);
> +		put_cpu_var(ppc64_tlb_batch);
>  		return;
>  	}
>  #endif /* CONFIG_PREEMPT_RT */
>  
>  	if (i >= PPC64_TLB_BATCH_NR)
>  		__flush_tlb_pending(batch);
> +	put_cpu_var(ppc64_tlb_batch);
>  }
>  
>  /*
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/platforms/pseries/eeh.c linux-2.6.23.1-rt4-fix/arch/powerpc/platforms/pseries/eeh.c
> --- linux-2.6.23.1-rt4/arch/powerpc/platforms/pseries/eeh.c	2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/arch/powerpc/platforms/pseries/eeh.c	2007-10-28 15:43:54.000000000 -0700
> @@ -97,7 +97,7 @@ int eeh_subsystem_enabled;
>  EXPORT_SYMBOL(eeh_subsystem_enabled);
>  
>  /* Lock to avoid races due to multiple reports of an error */
> -static DEFINE_SPINLOCK(confirm_error_lock);
> +static DEFINE_RAW_SPINLOCK(confirm_error_lock);
>  
>  /* Buffer for reporting slot-error-detail rtas calls. Its here
>   * in BSS, and not dynamically alloced, so that it ends up in
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/drivers/of/base.c linux-2.6.23.1-rt4-fix/drivers/of/base.c
> --- linux-2.6.23.1-rt4/drivers/of/base.c	2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/drivers/of/base.c	2007-10-28 13:38:36.000000000 -0700
> @@ -25,7 +25,7 @@ struct device_node *allnodes;
>  /* use when traversing tree through the allnext, child, sibling,
>   * or parent members of struct device_node.
>   */
> -DEFINE_RWLOCK(devtree_lock);
> +DEFINE_RAW_RWLOCK(devtree_lock);
>  
>  int of_n_addr_cells(struct device_node *np)
>  {
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/include/asm-powerpc/tlbflush.h linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlbflush.h
> --- linux-2.6.23.1-rt4/include/asm-powerpc/tlbflush.h	2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlbflush.h	2007-11-08 17:11:18.000000000 -0800
> @@ -109,18 +109,23 @@ extern void hpte_need_flush(struct mm_st
>  
>  static inline void arch_enter_lazy_mmu_mode(void)
>  {
> -	struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
> +	struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
>  
>  	batch->active = 1;
> +	put_cpu_var(ppc64_tlb_batch);
>  }
>  
>  static inline void arch_leave_lazy_mmu_mode(void)
>  {
> -	struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
> +	struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
>  
> -	if (batch->index)
> -		__flush_tlb_pending(batch);
> -	batch->active = 0;
> +	if (batch->active) {
> +		if (batch->index) {
> +			__flush_tlb_pending(batch);
> +		}
> +		batch->active = 0;
> +	}
> +	put_cpu_var(ppc64_tlb_batch);
>  }
>  
>  #define arch_flush_lazy_mmu_mode()      do {} while (0)
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/include/asm-powerpc/tlb.h linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlb.h
> --- linux-2.6.23.1-rt4/include/asm-powerpc/tlb.h	2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlb.h	2007-10-28 11:36:05.000000000 -0700
> @@ -44,8 +44,11 @@ static inline void tlb_flush(struct mmu_
>  	 * pages are going to be freed and we really don't want to have a CPU
>  	 * access a freed page because it has a stale TLB
>  	 */
> -	if (tlbbatch->index)
> +	if (tlbbatch->index) {
> +		preempt_disable();
>  		__flush_tlb_pending(tlbbatch);
> +		preempt_enable();
> +	}
>  
>  	pte_free_finish();
>  }