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VM: add "vm_mmap()" helper function

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This continues the theme started with vm_brk() and vm_munmap():
vm_mmap() does the same thing as do_mmap(), but additionally does the
required VM locking.

This uninlines (and rewrites it to be clearer) do_mmap(), which sadly
duplicates it in mm/mmap.c and mm/nommu.c.  But that way we don't have
to export our internal do_mmap_pgoff() function.

Some day we hopefully don't have to export do_mmap() either, if all
modular users can become the simpler vm_mmap() instead.  We're actually
very close to that already, with the notable exception of the (broken)
use in i810, and a couple of stragglers in binfmt_elf.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds
2012-04-20 17:13:58 -07:00
parent a46ef99d80
commit 6be5ceb02e
15 changed files with 87 additions and 97 deletions
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12
drivers/gpu/drm/drm_bufs.c
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@@ -1510,8 +1510,8 @@ int drm_freebufs(struct drm_device *dev, void *data,
* \param arg pointer to a drm_buf_map structure.
* \return zero on success or a negative number on failure.
*
* Maps the AGP, SG or PCI buffer region with do_mmap(), and copies information
* about each buffer into user space. For PCI buffers, it calls do_mmap() with
* Maps the AGP, SG or PCI buffer region with vm_mmap(), and copies information
* about each buffer into user space. For PCI buffers, it calls vm_mmap() with
* offset equal to 0, which drm_mmap() interpretes as PCI buffers and calls
* drm_mmap_dma().
*/
@@ -1553,18 +1553,14 @@ int drm_mapbufs(struct drm_device *dev, void *data,
retcode = -EINVAL;
goto done;
}
down_write(&current->mm->mmap_sem);
virtual = do_mmap(file_priv->filp, 0, map->size,
virtual = vm_mmap(file_priv->filp, 0, map->size,
PROT_READ | PROT_WRITE,
MAP_SHARED,
token);
up_write(&current->mm->mmap_sem);
} else {
down_write(&current->mm->mmap_sem);
virtual = do_mmap(file_priv->filp, 0, dma->byte_count,
virtual = vm_mmap(file_priv->filp, 0, dma->byte_count,
PROT_READ | PROT_WRITE,
MAP_SHARED, 0);
up_write(&current->mm->mmap_sem);
}
if (virtual > -1024UL) {
/* Real error */