[PATCH 12/42] userfaultfd: non-cooperative: optimize mremap_userfaultfd_complete()

[Andrea Arcangeli <aarcange@xxxxxxxxxx>]

Optimize the mremap_userfaultfd_complete() interface to pass only the
vm_userfaultfd_ctx pointer through the stack as a microoptimization.

Reported-by: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
 fs/userfaultfd.c              | 4 ++--
 include/linux/userfaultfd_k.h | 4 ++--
 mm/mremap.c                   | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index c047b6f..0b57045 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -575,11 +575,11 @@ void mremap_userfaultfd_prep(struct vm_area_struct *vma,
 	}
 }
 
-void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx vm_ctx,
+void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *vm_ctx,
 				 unsigned long from, unsigned long to,
 				 unsigned long len)
 {
-	struct userfaultfd_ctx *ctx = vm_ctx.ctx;
+	struct userfaultfd_ctx *ctx = vm_ctx->ctx;
 	struct userfaultfd_wait_queue ewq;
 
 	if (!ctx)
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 7f318a4..78ec197 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -57,7 +57,7 @@ extern void dup_userfaultfd_complete(struct list_head *);
 
 extern void mremap_userfaultfd_prep(struct vm_area_struct *,
 				    struct vm_userfaultfd_ctx *);
-extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx,
+extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *,
 					unsigned long from, unsigned long to,
 					unsigned long len);
 
@@ -100,7 +100,7 @@ static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
 {
 }
 
-static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx ctx,
+static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx,
 					       unsigned long from,
 					       unsigned long to,
 					       unsigned long len)
diff --git a/mm/mremap.c b/mm/mremap.c
index 504b560..8779928 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -608,6 +608,6 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 	up_write(&current->mm->mmap_sem);
 	if (locked && new_len > old_len)
 		mm_populate(new_addr + old_len, new_len - old_len);
-	mremap_userfaultfd_complete(uf, addr, new_addr, old_len);
+	mremap_userfaultfd_complete(&uf, addr, new_addr, old_len);
 	return ret;
 }

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