[PATCH RFC] x86/sgx: Do not increase encl->refcount for VMAs

[Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>]

Since the device file stays open up until all VMAs have been closed
we do not need to increase encl->refcount for VMAs. sgx_open() will
increase it once and sgx_release() will decrease at a point where
the device file is not mapped. anymore.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
Based on the commentary from Andy and Cedric.
 arch/x86/kernel/cpu/sgx/driver/main.c | 2 --
 arch/x86/kernel/cpu/sgx/encl.c        | 3 ---
 2 files changed, 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/driver/main.c b/arch/x86/kernel/cpu/sgx/driver/main.c
index 87735ce8b5ba..0c831ee5e2de 100644
--- a/arch/x86/kernel/cpu/sgx/driver/main.c
+++ b/arch/x86/kernel/cpu/sgx/driver/main.c
@@ -68,8 +68,6 @@ static int sgx_mmap(struct file *file, struct vm_area_struct *vma)
 	vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP | VM_IO;
 	vma->vm_private_data = encl;
 
-	kref_get(&encl->refcount);
-
 	return 0;
 }
 
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 6b190eccd02e..9566eb72d417 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -208,7 +208,6 @@ static void sgx_vma_open(struct vm_area_struct *vma)
 			goto error;
 	}
 
-	kref_get(&encl->refcount);
 	return;
 
 error:
@@ -230,8 +229,6 @@ static void sgx_vma_close(struct vm_area_struct *vma)
 		/* Release kref for the VMA. */
 		kref_put(&encl_mm->refcount, sgx_encl_mm_release);
 	}
-
-	kref_put(&encl->refcount, sgx_encl_release);
 }
 
 static unsigned int sgx_vma_fault(struct vm_fault *vmf)
-- 
2.20.1