Re: [PATCH v2 10/16] stm: replace deprecated mmap hook with mmap_prepare

[Suren Baghdasaryan <surenb@google.com>]

On Mon, Mar 16, 2026 at 2:14 PM Lorenzo Stoakes (Oracle) <ljs@kernel.org> wrote:
>
> The f_op->mmap interface is deprecated, so update driver to use its
> successor, mmap_prepare.
>
> The driver previously used vm_iomap_memory(), so this change replaces it
> with its mmap_prepare equivalent, mmap_action_simple_ioremap().
>
> Also, in order to correctly maintain reference counting, add a
> vm_ops->mapped callback to increment the reference count when successfully
> mapped.
>
> Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

Reviewed-by: Suren Baghdasaryan <surenb@google.com>

> ---
>  drivers/hwtracing/stm/core.c | 31 +++++++++++++++++++++----------
>  1 file changed, 21 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
> index 37584e786bb5..f48c6a8a0654 100644
> --- a/drivers/hwtracing/stm/core.c
> +++ b/drivers/hwtracing/stm/core.c
> @@ -666,6 +666,16 @@ static ssize_t stm_char_write(struct file *file, const char __user *buf,
>         return count;
>  }
>
> +static int stm_mmap_mapped(unsigned long start, unsigned long end, pgoff_t pgoff,
> +                          const struct file *file, void **vm_private_data)
> +{
> +       struct stm_file *stmf = file->private_data;
> +       struct stm_device *stm = stmf->stm;
> +
> +       pm_runtime_get_sync(&stm->dev);
> +       return 0;
> +}
> +
>  static void stm_mmap_open(struct vm_area_struct *vma)
>  {
>         struct stm_file *stmf = vma->vm_file->private_data;
> @@ -684,12 +694,14 @@ static void stm_mmap_close(struct vm_area_struct *vma)
>  }
>
>  static const struct vm_operations_struct stm_mmap_vmops = {
> +       .mapped = stm_mmap_mapped,
>         .open   = stm_mmap_open,
>         .close  = stm_mmap_close,
>  };
>
> -static int stm_char_mmap(struct file *file, struct vm_area_struct *vma)
> +static int stm_char_mmap_prepare(struct vm_area_desc *desc)
>  {
> +       struct file *file = desc->file;
>         struct stm_file *stmf = file->private_data;
>         struct stm_device *stm = stmf->stm;
>         unsigned long size, phys;
> @@ -697,10 +709,10 @@ static int stm_char_mmap(struct file *file, struct vm_area_struct *vma)
>         if (!stm->data->mmio_addr)
>                 return -EOPNOTSUPP;
>
> -       if (vma->vm_pgoff)
> +       if (desc->pgoff)
>                 return -EINVAL;
>
> -       size = vma->vm_end - vma->vm_start;
> +       size = vma_desc_size(desc);
>
>         if (stmf->output.nr_chans * stm->data->sw_mmiosz != size)
>                 return -EINVAL;
> @@ -712,13 +724,12 @@ static int stm_char_mmap(struct file *file, struct vm_area_struct *vma)
>         if (!phys)
>                 return -EINVAL;
>
> -       pm_runtime_get_sync(&stm->dev);
> -
> -       vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> -       vm_flags_set(vma, VM_IO | VM_DONTEXPAND | VM_DONTDUMP);
> -       vma->vm_ops = &stm_mmap_vmops;
> -       vm_iomap_memory(vma, phys, size);
> +       desc->page_prot = pgprot_noncached(desc->page_prot);
> +       vma_desc_set_flags(desc, VMA_IO_BIT, VMA_DONTEXPAND_BIT,
> +                          VMA_DONTDUMP_BIT);
> +       desc->vm_ops = &stm_mmap_vmops;
>
> +       mmap_action_simple_ioremap(desc, phys, size);
>         return 0;
>  }
>
> @@ -836,7 +847,7 @@ static const struct file_operations stm_fops = {
>         .open           = stm_char_open,
>         .release        = stm_char_release,
>         .write          = stm_char_write,
> -       .mmap           = stm_char_mmap,
> +       .mmap_prepare   = stm_char_mmap_prepare,
>         .unlocked_ioctl = stm_char_ioctl,
>         .compat_ioctl   = compat_ptr_ioctl,
>  };
> --
> 2.53.0
>