Subject: Re: [PATCH v2 2/4] CXL: Refactor cxl_load_segment and find_free_sste

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Tue, 28 Oct 2014 13:43:12 +0530

Ian Munsie <[email-masked]> writes:

> From: Ian Munsie <[email-masked]>
>
> This moves the segment table hash calculation from cxl_load_segment into
> find_free_sste since that is the only place it is actually used.
>
> Signed-off-by: Ian Munsie <[email-masked]>

Reviewed-by: Aneesh Kumar K.V <[email-masked]>

> ---
>  drivers/misc/cxl/fault.c | 34 ++++++++++++++++++----------------
>  1 file changed, 18 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c
> index d0e97fd..cb4f323 100644
> --- a/drivers/misc/cxl/fault.c
> +++ b/drivers/misc/cxl/fault.c
> @@ -21,20 +21,30 @@
>  
>  #include "cxl.h"
>  
> -static struct cxl_sste* find_free_sste(struct cxl_sste *primary_group,
> -				       unsigned int *lru)
> +/* This finds a free SSTE for the given SLB */
> +static struct cxl_sste* find_free_sste(struct cxl_context *ctx,
> +				       struct copro_slb *slb)
>  {
> +	struct cxl_sste *primary, *sste;
> +	unsigned int mask = (ctx->sst_size >> 7) - 1; /* SSTP0[SegTableSize] */
>  	unsigned int entry;
> -	struct cxl_sste *sste, *group = primary_group;
> +	unsigned int hash;
> +
> +	if (slb->vsid & SLB_VSID_B_1T)
> +		hash = (slb->esid >> SID_SHIFT_1T) & mask;
> +	else /* 256M */
> +		hash = (slb->esid >> SID_SHIFT) & mask;
>  
> -	for (entry = 0; entry < 8; entry++) {
> -		sste = group + entry;
> +	primary = ctx->sstp + (hash << 3);
> +
> +	for (entry = 0, sste = primary; entry < 8; entry++, sste++) {
>  		if (!(be64_to_cpu(sste->esid_data) & SLB_ESID_V))
>  			return sste;
>  	}
> +
>  	/* Nothing free, select an entry to cast out */
> -	sste = primary_group + *lru;
> -	*lru = (*lru + 1) & 0x7;
> +	sste = primary + ctx->sst_lru;
> +	ctx->sst_lru = (ctx->sst_lru + 1) & 0x7;
>  
>  	return sste;
>  }
> @@ -42,19 +52,11 @@ static struct cxl_sste* find_free_sste(struct cxl_sste *primary_group,
>  static void cxl_load_segment(struct cxl_context *ctx, struct copro_slb *slb)
>  {
>  	/* mask is the group index, we search primary and secondary here. */
> -	unsigned int mask = (ctx->sst_size >> 7)-1; /* SSTP0[SegTableSize] */
>  	struct cxl_sste *sste;
> -	unsigned int hash;
>  	unsigned long flags;
>  
> -
> -	if (slb->vsid & SLB_VSID_B_1T)
> -		hash = (slb->esid >> SID_SHIFT_1T) & mask;
> -	else /* 256M */
> -		hash = (slb->esid >> SID_SHIFT) & mask;
> -
>  	spin_lock_irqsave(&ctx->sste_lock, flags);
> -	sste = find_free_sste(ctx->sstp + (hash << 3), &ctx->sst_lru);
> +	sste = find_free_sste(ctx, slb);
>  
>  	pr_devel("CXL Populating SST[%li]: %#llx %#llx\n",
>  			sste - ctx->sstp, slb->vsid, slb->esid);
> -- 
> 2.1.1
>
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