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

Dan Carpenter
2014-02-10T15:29:14Z

On Mon, Feb 10, 2014 at 07:22:02AM -0800, James Bottomley wrote:
> 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.
>

Ah. I was wondering what that was. Thanks. I will resend.

regards,
dan carpenter