linux-kernel - Re: [PATCH 2/4] staging: kpc2000: kpc_dma: Convert set_page_dirty() --> set_page_dirty

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Date:   Sat, 27 Jun 2020 23:21:18 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>, jane.pnx9@...il.com,
        pakki001@....edu, ldufour@...ux.ibm.com, harshjain32@...il.com,
        Simon Sandström <simon@...anor.nu>,
        Michel Lespinasse <walken@...gle.com>
Cc:     "open list:ANDROID DRIVERS" <devel@...verdev.osuosl.org>,
        linux-kernel@...r.kernel.org,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Bharath Vedartham <linux.bhar@...il.com>
Subject: Re: [PATCH 2/4] staging: kpc2000: kpc_dma: Convert set_page_dirty()
 --> set_page_dirty_lock()

On Wed, Jun 17, 2020 at 7:50 AM Souptick Joarder <jrdr.linux@...il.com> wrote:
>
> First, convert set_page_dirty() to set_page_dirty_lock()
>
> Second, there is an interval in there after set_page_dirty() and
> before put_page(), in which the device could be running and setting
> pages dirty. Moving set_page_dirty_lock() after dma_unmap_sg().
>
> Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
> Suggested-by: John Hubbard <jhubbard@...dia.com>
> Cc: Dan Carpenter <dan.carpenter@...cle.com>
> Cc: Bharath Vedartham <linux.bhar@...il.com>
> ---
>  drivers/staging/kpc2000/kpc_dma/fileops.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
> index b136353..bcce86c 100644
> --- a/drivers/staging/kpc2000/kpc_dma/fileops.c
> +++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
> @@ -214,13 +214,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
>         BUG_ON(!acd->ldev);
>         BUG_ON(!acd->ldev->pldev);
>
> +       dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
> +
>         for (i = 0 ; i < acd->page_count ; i++) {
>                 if (!PageReserved(acd->user_pages[i]))

Question -> is PageReserved() used with specific purpose not PageDirty() ??

> -                       set_page_dirty(acd->user_pages[i]);
> +                       set_page_dirty_lock(acd->user_pages[i]);
>         }
>
> -       dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
> -
>         for (i = 0 ; i < acd->page_count ; i++)
>                 put_page(acd->user_pages[i]);
>
> --
> 1.9.1
>