[PATCH v4 49/66] bpf: Remove VMA linked list

[Liam Howlett]

From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>

Use vma_next() and remove reference to the start of the linked list

Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
---
 kernel/bpf/task_iter.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index b48750bfba5a..2d964743f1e6 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -299,8 +299,8 @@ struct bpf_iter_seq_task_vma_info {
 };
 
 enum bpf_task_vma_iter_find_op {
-	task_vma_iter_first_vma,   /* use mm->mmap */
-	task_vma_iter_next_vma,    /* use curr_vma->vm_next */
+	task_vma_iter_first_vma,   /* use find_vma() with addr 0 */
+	task_vma_iter_next_vma,    /* use vma_next() with curr_vma */
 	task_vma_iter_find_vma,    /* use find_vma() to find next vma */
 };
 
@@ -400,24 +400,11 @@ task_vma_seq_get_next(struct bpf_iter_seq_task_vma_info *info)
 
 	switch (op) {
 	case task_vma_iter_first_vma:
-		curr_vma = curr_task->mm->mmap;
+		curr_vma = find_vma(curr_task->mm, 0);
 		break;
 	case task_vma_iter_next_vma:
-		curr_vma = curr_vma->vm_next;
-		break;
 	case task_vma_iter_find_vma:
-		/* We dropped mmap_lock so it is necessary to use find_vma
-		 * to find the next vma. This is similar to the  mechanism
-		 * in show_smaps_rollup().
-		 */
-		curr_vma = find_vma(curr_task->mm, info->prev_vm_end - 1);
-		/* case 1) and 4.2) above just use curr_vma */
-
-		/* check for case 2) or case 4.1) above */
-		if (curr_vma &&
-		    curr_vma->vm_start == info->prev_vm_start &&
-		    curr_vma->vm_end == info->prev_vm_end)
-			curr_vma = curr_vma->vm_next;
+		curr_vma = find_vma(curr_task->mm, curr_vma->vm_end);
 		break;
 	}
 	if (!curr_vma) {
-- 
2.30.2