Re: [patch v2] [SCSI] arcmsr: upper 32 of dma address lost

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Mon, 2014-02-10 at 18:18 +0300, Dan Carpenter wrote:
> The original code always set the upper 32 bits to zero because it was
> doing a shift of the wrong variable.
> 
> Fixes: 1a4f550a09f8 ('[SCSI] arcmsr: 1.20.00.15: add SATA RAID plus other fixes')
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> v2: Add a cast to u64 to avoid a future static checker warning
> 
> diff --git a/drivers/scsi/arcmsr/arcmsr_hba.c b/drivers/scsi/arcmsr/arcmsr_hba.c
> index 4f6a30b8e5f9..9cfd399c47c0 100644
> --- a/drivers/scsi/arcmsr/arcmsr_hba.c
> +++ b/drivers/scsi/arcmsr/arcmsr_hba.c
> @@ -2500,16 +2500,15 @@ static int arcmsr_polling_ccbdone(struct AdapterControlBlock *acb,
>  static int arcmsr_iop_confirm(struct AdapterControlBlock *acb)
>  {
>  	uint32_t cdb_phyaddr, cdb_phyaddr_hi32;
> -	dma_addr_t dma_coherent_handle;
> +
>  	/*
>  	********************************************************************
>  	** here we need to tell iop 331 our freeccb.HighPart
>  	** if freeccb.HighPart is not zero
>  	********************************************************************
>  	*/
> -	dma_coherent_handle = acb->dma_coherent_handle;
> -	cdb_phyaddr = (uint32_t)(dma_coherent_handle);
> -	cdb_phyaddr_hi32 = (uint32_t)((cdb_phyaddr >> 16) >> 16);
> +	cdb_phyaddr = (uint32_t)(acb->dma_coherent_handle);
> +	cdb_phyaddr_hi32 = (uint32_t)((u64)acb->dma_coherent_handle >> 32);

The original 16 >> 16 is better because there's no requirement to cast
to u64 and take an expensive 64 bit build out on 32 bits just to avoid
the warning.

There's actually a macro in kernel.h (upper_32_bits) that does this.

James

>  	acb->cdb_phyaddr_hi32 = cdb_phyaddr_hi32;
>  	/*
>  	***********************************************************************
> 
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