uprobes: Simplify the usage of uprobe->pending_list

uprobe->pending_list is only used to create the temporary list,
it has no meaning after we drop uprobes_mmap_hash(inode).

No need to initialize this node or remove it from tmp_list, and
we can use list_for_each_entry().

Signed-off-by: Oleg Nesterov <[email protected]>
Cc: Ananth N Mavinakayanahalli <[email protected]>
Cc: Anton Arapov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Srikar Dronamraju <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

kernel/events/uprobes.c

@@ -513,7 +513,6 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
 	uprobe->inode = igrab(inode);
 	uprobe->offset = offset;
 	init_rwsem(&uprobe->consumer_rwsem);
-	INIT_LIST_HEAD(&uprobe->pending_list);
 
 	/* add to uprobes_tree, sorted on inode:offset */
 	cur_uprobe = insert_uprobe(uprobe);
@@ -1037,7 +1036,7 @@ static void build_probe_list(struct inode *inode, struct list_head *head)
 int uprobe_mmap(struct vm_area_struct *vma)
 {
 	struct list_head tmp_list;
-	struct uprobe *uprobe, *u;
+	struct uprobe *uprobe;
 	struct inode *inode;
 	int ret, count;
 
@@ -1055,10 +1054,9 @@ int uprobe_mmap(struct vm_area_struct *vma)
 	ret = 0;
 	count = 0;
 
-	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
+	list_for_each_entry(uprobe, &tmp_list, pending_list) {
 		loff_t vaddr;
 
-		list_del(&uprobe->pending_list);
 		if (!ret) {
 			vaddr = vma_address(vma, uprobe->offset);
 
@@ -1106,7 +1104,7 @@ int uprobe_mmap(struct vm_area_struct *vma)
 void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
 {
 	struct list_head tmp_list;
-	struct uprobe *uprobe, *u;
+	struct uprobe *uprobe;
 	struct inode *inode;
 
 	if (!atomic_read(&uprobe_events) || !valid_vma(vma, false))
@@ -1123,12 +1121,10 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
 	mutex_lock(uprobes_mmap_hash(inode));
 	build_probe_list(inode, &tmp_list);
 
-	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
+	list_for_each_entry(uprobe, &tmp_list, pending_list) {
 		loff_t vaddr;
 
-		list_del(&uprobe->pending_list);
 		vaddr = vma_address(vma, uprobe->offset);
-
 		if (vaddr >= start && vaddr < end) {
 			/*
 			 * An unregister could have removed the probe before