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SubjectRe: [PATCH] Staging: TIDSPBRIDGE: Use vm_iomap_memory for mmap-ing instead of remap_pfn_range

On 08.12.2013 01:49, Steven Luo wrote:
> This patch causes problems with DSP codecs on OMAP3 devices running
> Android -- specifically, when the decoder is cleaning up after itself,
> munmap() of the mapped area fails, leading to a memory leak which
> eventually crashes the system.
>
> As far as I can tell, the code with this patch applied reduces to
> (ignoring checks and such)
>
> remap_pfn_range(vma, vma->vm_start,
> (pdata->phys_mempool_base >> PAGE_SHIFT) + vma->vm_pgoff,
> vma->vm_end - vma->vm_start,
> vma->vm_page_prot);
>
> whereas the original was
>
>> - status = remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
>> - vma->vm_end - vma->vm_start,
>> - vma->vm_page_prot);
> We're subtracting (pdata->phys_mempool_base >> PAGE_SHIFT) from
> vma->vm_pgoff before calling vm_iomap_memory() to address the issue --
> if that's satisfactory to everyone involved, I can submit the following
> patch.
>
> -Steven Luo
>
> (please cc, not subscribed)
>
> From: Steven Luo <steven@steven676.net>
> Date: Sat, 7 Dec 2013 02:11:20 -0800
> Subject: [PATCH] tidspbridge: fix last patch to map same region of physical
> memory as before
>
> Commit 559c71fe5dc3 ("Staging: TIDSPBRIDGE: Use vm_iomap_memory for
> mmap-ing instead of remap_pfn_range") had the effect of inadvertently
> shifting the start of the physical memory area mapped by
> pdata->phys_mempool_base. Correct this by subtracting that shift before
> calling vm_iomap_memory() and adding it back afterwards.
>
> Reported-by: Dheeraj CVR <cvr.dheeraj@gmail.com>
> Signed-off-by: Steven Luo <steven@steven676.net>
> ---
> drivers/staging/tidspbridge/rmgr/drv_interface.c | 29 +++++++++++++++++++---
> 1 file changed, 26 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/tidspbridge/rmgr/drv_interface.c b/drivers/staging/tidspbridge/rmgr/drv_interface.c
> index 83cc3a5..d7f7d04 100644
> --- a/drivers/staging/tidspbridge/rmgr/drv_interface.c
> +++ b/drivers/staging/tidspbridge/rmgr/drv_interface.c
> @@ -258,6 +258,9 @@ err:
> /* This function maps kernel space memory to user space memory. */
> static int bridge_mmap(struct file *filp, struct vm_area_struct *vma)
> {
> + unsigned long base_pgoff;
> + int status;
> +
> struct omap_dsp_platform_data *pdata =
> omap_dspbridge_dev->dev.platform_data;
>
> @@ -269,9 +272,29 @@ static int bridge_mmap(struct file *filp, struct vm_area_struct *vma)
> vma->vm_start, vma->vm_end, vma->vm_page_prot,
> vma->vm_flags);
>
> - return vm_iomap_memory(vma,
> - pdata->phys_mempool_base,
> - pdata->phys_mempool_size);
> + /*
> + * vm_iomap_memory() expects vma->vm_pgoff to be expressed as an offset
> + * from the start of the physical memory pool, but we're called with
> + * a pfn (physical page number) stored there instead.
> + *
> + * To avoid duplicating lots of tricky overflow checking logic,
> + * temporarily convert vma->vm_pgoff to the offset vm_iomap_memory()
> + * expects, but restore the original value once the mapping has been
> + * created.
> + */
> + base_pgoff = pdata->phys_mempool_base >> PAGE_SHIFT;
> + if (vma->vm_pgoff < base_pgoff)
> + return -EINVAL;
> + vma->vm_pgoff -= base_pgoff;
> +
> + status = vm_iomap_memory(vma,
> + pdata->phys_mempool_base,
> + pdata->phys_mempool_size);
> +
> + /* Restore the original value of vma->vm_pgoff */
> + vma->vm_pgoff += base_pgoff;
> +
> + return status;
> }
>
> static const struct file_operations bridge_fops = {
Tested on Nokia N900 with Maemo 5 and Harmattan codec nodes


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