[PATCH 20/29] drm/gma500: Add driver private mutex for the fault handler

[Daniel Vetter]

There's currently two places where the gma500 fault handler relies
upon dev->struct_mutex:
- To protect r->mappping
- To make sure vm_insert_pfn isn't called concurrently (in which case
  the 2nd thread would get an error code).

Everything else (specifically psb_gtt_pin) is already protected by
some other locks. Hence just create a new driver-private mmap_mutex
just for this function.

With this gma500 is complete dev->struct_mutex free!

Cc: Patrik Jakobsson <patrik.r.jakobsson at gmail.com>
Acked-by: Patrik Jakobsson <patrik.r.jakobsson at gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 drivers/gpu/drm/gma500/gem.c     | 4 ++--
 drivers/gpu/drm/gma500/gtt.c     | 1 +
 drivers/gpu/drm/gma500/psb_drv.h | 2 ++
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/gma500/gem.c b/drivers/gpu/drm/gma500/gem.c
index f0357f525f56..506224b3a0ad 100644
--- a/drivers/gpu/drm/gma500/gem.c
+++ b/drivers/gpu/drm/gma500/gem.c
@@ -182,7 +182,7 @@ int psb_gem_fault(struct vm_area_struct *vma, struct 
vm_fault *vmf)

        /* Make sure we don't parallel update on a fault, nor move or remove
           something from beneath our feet */
-       mutex_lock(&dev->struct_mutex);
+       mutex_lock(&dev_priv->mmap_mutex);

        /* For now the mmap pins the object and it stays pinned. As things
           stand that will do us no harm */
@@ -208,7 +208,7 @@ int psb_gem_fault(struct vm_area_struct *vma, struct 
vm_fault *vmf)
        ret = vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);

 fail:
-       mutex_unlock(&dev->struct_mutex);
+       mutex_unlock(&dev_priv->mmap_mutex);
        switch (ret) {
        case 0:
        case -ERESTARTSYS:
diff --git a/drivers/gpu/drm/gma500/gtt.c b/drivers/gpu/drm/gma500/gtt.c
index ce015db59dc6..8f69225ce2b4 100644
--- a/drivers/gpu/drm/gma500/gtt.c
+++ b/drivers/gpu/drm/gma500/gtt.c
@@ -425,6 +425,7 @@ int psb_gtt_init(struct drm_device *dev, int resume)

        if (!resume) {
                mutex_init(&dev_priv->gtt_mutex);
+               mutex_init(&dev_priv->mmap_mutex);
                psb_gtt_alloc(dev);
        }

diff --git a/drivers/gpu/drm/gma500/psb_drv.h b/drivers/gpu/drm/gma500/psb_drv.h
index e21726ecac32..3bd2c726dd61 100644
--- a/drivers/gpu/drm/gma500/psb_drv.h
+++ b/drivers/gpu/drm/gma500/psb_drv.h
@@ -465,6 +465,8 @@ struct drm_psb_private {
        struct mutex gtt_mutex;
        struct resource *gtt_mem;       /* Our PCI resource */

+       struct mutex mmap_mutex;
+
        struct psb_mmu_driver *mmu;
        struct psb_mmu_pd *pf_pd;

-- 
2.5.1