From: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Reduce the exposure of struct_mutex to an absolute minimum. We only
need to take this lock over the call to etnaviv_gem_get_pages() as
vm_insert_page() already does a properly synchronised update of the
PTE (using the pte table lock.)
Reducing the code covered by this lock allows for more parallel
execution in SMP environments.
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
---
drivers/staging/etnaviv/etnaviv_gem.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/staging/etnaviv/etnaviv_gem.c b/drivers/staging/etnaviv/etnaviv_gem.c
index 69360c899b78..522e5a6c3612 100644
--- a/drivers/staging/etnaviv/etnaviv_gem.c
+++ b/drivers/staging/etnaviv/etnaviv_gem.c
@@ -221,8 +221,10 @@ int etnaviv_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
pgoff_t pgoff;
int ret;
- /* Make sure we don't parallel update on a fault, nor move or remove
- * something from beneath our feet
+ /*
+ * Make sure we don't parallel update on a fault, nor move or remove
+ * something from beneath our feet. Note that vm_insert_page() is
+ * specifically coded to take care of this, so we don't have to.
*/
ret = mutex_lock_interruptible(&dev->struct_mutex);
if (ret)
@@ -230,9 +232,11 @@ int etnaviv_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
/* make sure we have pages attached now */
pages = etnaviv_gem_get_pages(to_etnaviv_bo(obj));
+ mutex_unlock(&dev->struct_mutex);
+
if (IS_ERR(pages)) {
ret = PTR_ERR(pages);
- goto out_unlock;
+ goto out;
}
/* We don't use vmf->pgoff since that has the fake offset: */
@@ -246,8 +250,6 @@ int etnaviv_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
ret = vm_insert_page(vma, (unsigned long)vmf->virtual_address, page);
-out_unlock:
- mutex_unlock(&dev->struct_mutex);
out:
switch (ret) {
case -EAGAIN:
--
2.5.1
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