linux-kernel - Re: [PATCH] scsi/mvsas/mv_init.c: Use dma_zalloc

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Date:   Sat, 5 Jan 2019 01:19:39 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     John Garry <john.garry@...wei.com>
Cc:     Sabyasachi Gupta <sabyasachi.linux@...il.com>,
        James Bottomley <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        linux-scsi <linux-scsi@...r.kernel.org>,
        linux-kernel@...r.kernel.org,
        Brajeswar Ghosh <brajeswar.linux@...il.com>
Subject: Re: [PATCH] scsi/mvsas/mv_init.c: Use dma_zalloc_coherent

On Fri, Jan 4, 2019 at 9:34 PM John Garry <john.garry@...wei.com> wrote:
>
> On 04/01/2019 15:11, Sabyasachi Gupta wrote:
> > On Fri, Jan 4, 2019 at 6:43 PM John Garry <john.garry@...wei.com> wrote:
> >>
> >> On 04/01/2019 12:48, Sabyasachi Gupta wrote:
> >>> On Wed, Dec 19, 2018 at 6:49 PM Sabyasachi Gupta
> >>> <sabyasachi.linux@...il.com> wrote:
> >>>>
> >>>> On Sat, Dec 1, 2018 at 6:40 PM Sabyasachi Gupta
> >>>> <sabyasachi.linux@...il.com> wrote:
> >>>>>
> >>>>> On Wed, Nov 21, 2018 at 7:18 PM Sabyasachi Gupta
> >>>>> <sabyasachi.linux@...il.com> wrote:
> >>>>>>
> >>>>>> Replace dma_alloc_coherent + memset with dma_zalloc_coherent
> >>>>>>
> >>
> >> If you're going to make this change, then how about change these to the
> >> managed version, so that we can avoid the explicit free'ing at driver
> >> removal?
> >
> > I can't get it
>
> Please see dmam_alloc_coherent(). You can set __GFP_ZERO in the gfp
> argument to memset(0).

and dma_zalloc_coherent() did the same. So both are same right ? No ?

>
> I would say that this is a more useful change.
>
> >
> >>
> >>>>>> Signed-off-by: Sabyasachi Gupta <sabyasachi.linux@...il.com>
> >>>>>
> >>>>> Any comment on this patch?
> >>>>
> >>>> Any comment on this patch?
> >>>
> >>> Any comment on this patch?
> >>>
> >>>>
> >>>>>
> >>>>>> ---
> >>>>>>  drivers/scsi/mvsas/mv_init.c | 12 ++++--------
> >>>>>>  1 file changed, 4 insertions(+), 8 deletions(-)
> >>>>>>
> >>>>>> diff --git a/drivers/scsi/mvsas/mv_init.c b/drivers/scsi/mvsas/mv_init.c
> >>>>>> index 3ac3437..495bddb 100644
> >>>>>> --- a/drivers/scsi/mvsas/mv_init.c
> >>>>>> +++ b/drivers/scsi/mvsas/mv_init.c
> >>>>>> @@ -253,33 +253,29 @@ static int mvs_alloc(struct mvs_info *mvi, struct Scsi_Host *shost)
> >>>>>>         /*
> >>>>>>          * alloc and init our DMA areas
> >>>>>>          */
> >>>>>> -       mvi->tx = dma_alloc_coherent(mvi->dev,
> >>>>>> +       mvi->tx = dma_zalloc_coherent(mvi->dev,
> >>>>>>                                      sizeof(*mvi->tx) * MVS_CHIP_SLOT_SZ,
> >>>>>>                                      &mvi->tx_dma, GFP_KERNEL);
> >>
> >> I'm guessing that this does not pass checkpatch with --strict option.
> >>
> >> Thanks,
> >> John
> >
> > I have not not checked with --strict option
>
> It may warn that you're not maintaining alignment.
>
> >
> >>
> >>>>>>         if (!mvi->tx)
> >>>>>>                 goto err_out;
> >>>>>> -       memset(mvi->tx, 0, sizeof(*mvi->tx) * MVS_CHIP_SLOT_SZ);
> >>>>>> -       mvi->rx_fis = dma_alloc_coherent(mvi->dev, MVS_RX_FISL_SZ,
> >>>>>> +       mvi->rx_fis = dma_zalloc_coherent(mvi->dev, MVS_RX_FISL_SZ,
> >>>>>>                                          &mvi->rx_fis_dma, GFP_KERNEL);
> >>>>>>         if (!mvi->rx_fis)
> >>>>>>                 goto err_out;
> >>>>>> -       memset(mvi->rx_fis, 0, MVS_RX_FISL_SZ);
> >>>>>>
> >>>>>> -       mvi->rx = dma_alloc_coherent(mvi->dev,
> >>>>>> +       mvi->rx = dma_zalloc_coherent(mvi->dev,
> >>>>>>                                      sizeof(*mvi->rx) * (MVS_RX_RING_SZ + 1),
> >>>>>>                                      &mvi->rx_dma, GFP_KERNEL);
> >>>>>>         if (!mvi->rx)
> >>>>>>                 goto err_out;
> >>>>>> -       memset(mvi->rx, 0, sizeof(*mvi->rx) * (MVS_RX_RING_SZ + 1));
> >>>>>>         mvi->rx[0] = cpu_to_le32(0xfff);
> >>>>>>         mvi->rx_cons = 0xfff;
> >>>>>>
> >>>>>> -       mvi->slot = dma_alloc_coherent(mvi->dev,
> >>>>>> +       mvi->slot = dma_zalloc_coherent(mvi->dev,
> >>>>>>                                        sizeof(*mvi->slot) * slot_nr,
> >>>>>>                                        &mvi->slot_dma, GFP_KERNEL);
> >>>>>>         if (!mvi->slot)
> >>>>>>                 goto err_out;
> >>>>>> -       memset(mvi->slot, 0, sizeof(*mvi->slot) * slot_nr);
> >>>>>>
> >>>>>>         mvi->bulk_buffer = dma_alloc_coherent(mvi->dev,
> >>>>>>                                        TRASH_BUCKET_SIZE,
> >>>>>> --
> >>>>>> 2.7.4
> >>>>>>
> >>>
> >>> .
> >>>
> >>
> >>
> >
> > .
> >
>
>