1 files changed, 86 insertions, 113 deletions

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index ec78152e32e9..4e0db3496d70 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -60,17 +60,6 @@ static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ];
  */
 static atomic_t uprobe_events = ATOMIC_INIT(0);
 
-/*
- * Maintain a temporary per vma info that can be used to search if a vma
- * has already been handled. This structure is introduced since extending
- * vm_area_struct wasnt recommended.
- */
-struct vma_info {
-        struct list_head        probe_list;
-        struct mm_struct        *mm;
-        loff_t                  vaddr;
-};
-
 struct uprobe {
         struct rb_node          rb_node;        /* node in the rb tree */
         atomic_t                ref;
@@ -742,139 +731,123 @@ static void delete_uprobe(struct uprobe *uprobe)
         atomic_dec(&uprobe_events);
 }
 
-static struct vma_info *
-__find_next_vma_info(struct address_space *mapping, struct list_head *head,
-                        struct vma_info *vi, loff_t offset, bool is_register)
+struct map_info {
+        struct map_info *next;
+        struct mm_struct *mm;
+        loff_t vaddr;
+};
+
+static inline struct map_info *free_map_info(struct map_info *info)
 {
+        struct map_info *next = info->next;
+        kfree(info);
+        return next;
+}
+
+static struct map_info *
+build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
+{
+        unsigned long pgoff = offset >> PAGE_SHIFT;
         struct prio_tree_iter iter;
         struct vm_area_struct *vma;
-        struct vma_info *tmpvi;
-        unsigned long pgoff;
-        int existing_vma;
-        loff_t vaddr;
-
-        pgoff = offset >> PAGE_SHIFT;
+        struct map_info *curr = NULL;
+        struct map_info *prev = NULL;
+        struct map_info *info;
+        int more = 0;
 
+ again:
+        mutex_lock(&mapping->i_mmap_mutex);
         vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
                 if (!valid_vma(vma, is_register))
                         continue;
 
-                existing_vma = 0;
-                vaddr = vma_address(vma, offset);
-
-                list_for_each_entry(tmpvi, head, probe_list) {
-                        if (tmpvi->mm == vma->vm_mm && tmpvi->vaddr == vaddr) {
-                                existing_vma = 1;
-                                break;
-                        }
-                }
-
-                /*
-                 * Another vma needs a probe to be installed. However skip
-                 * installing the probe if the vma is about to be unlinked.
-                 */
-                if (!existing_vma && atomic_inc_not_zero(&vma->vm_mm->mm_users)) {
-                        vi->mm = vma->vm_mm;
-                        vi->vaddr = vaddr;
-                        list_add(&vi->probe_list, head);
-
-                        return vi;
+                if (!prev) {
+                        more++;
+                        continue;
                 }
-        }
-
-        return NULL;
-}
 
-/*
- * Iterate in the rmap prio tree  and find a vma where a probe has not
- * yet been inserted.
- */
-static struct vma_info *
-find_next_vma_info(struct address_space *mapping, struct list_head *head,
-                loff_t offset, bool is_register)
-{
-        struct vma_info *vi, *retvi;
+                if (!atomic_inc_not_zero(&vma->vm_mm->mm_users))
+                        continue;
 
-        vi = kzalloc(sizeof(struct vma_info), GFP_KERNEL);
-        if (!vi)
-                return ERR_PTR(-ENOMEM);
+                info = prev;
+                prev = prev->next;
+                info->next = curr;
+                curr = info;
 
-        mutex_lock(&mapping->i_mmap_mutex);
-        retvi = __find_next_vma_info(mapping, head, vi, offset, is_register);
+                info->mm = vma->vm_mm;
+                info->vaddr = vma_address(vma, offset);
+        }
         mutex_unlock(&mapping->i_mmap_mutex);
 
-        if (!retvi)
-                kfree(vi);
+        if (!more)
+                goto out;
+
+        prev = curr;
+        while (curr) {
+                mmput(curr->mm);
+                curr = curr->next;
+        }
 
-        return retvi;
+        do {
+                info = kmalloc(sizeof(struct map_info), GFP_KERNEL);
+                if (!info) {
+                        curr = ERR_PTR(-ENOMEM);
+                        goto out;
+                }
+                info->next = prev;
+                prev = info;
+        } while (--more);
+
+        goto again;
+ out:
+        while (prev)
+                prev = free_map_info(prev);
+        return curr;
 }
 
 static int register_for_each_vma(struct uprobe *uprobe, bool is_register)
 {
-        struct list_head try_list;
-        struct vm_area_struct *vma;
-        struct address_space *mapping;
-        struct vma_info *vi, *tmpvi;
-        struct mm_struct *mm;
-        loff_t vaddr;
-        int ret;
+        struct map_info *info;
+        int err = 0;
 
-        mapping = uprobe->inode->i_mapping;
-        INIT_LIST_HEAD(&try_list);
-
-        ret = 0;
+        info = build_map_info(uprobe->inode->i_mapping,
+                                        uprobe->offset, is_register);
+        if (IS_ERR(info))
+                return PTR_ERR(info);
 
-        for (;;) {
-                vi = find_next_vma_info(mapping, &try_list, uprobe->offset, is_register);
-                if (!vi)
-                        break;
+        while (info) {
+                struct mm_struct *mm = info->mm;
+                struct vm_area_struct *vma;
+                loff_t vaddr;
 
-                if (IS_ERR(vi)) {
-                        ret = PTR_ERR(vi);
-                        break;
-                }
+                if (err)
+                        goto free;
 
-                mm = vi->mm;
                 down_write(&mm->mmap_sem);
-                vma = find_vma(mm, (unsigned long)vi->vaddr);
-                if (!vma || !valid_vma(vma, is_register)) {
-                        list_del(&vi->probe_list);
-                        kfree(vi);
-                        up_write(&mm->mmap_sem);
-                        mmput(mm);
-                        continue;
-                }
+                vma = find_vma(mm, (unsigned long)info->vaddr);
+                if (!vma || !valid_vma(vma, is_register))
+                        goto unlock;
+
                 vaddr = vma_address(vma, uprobe->offset);
                 if (vma->vm_file->f_mapping->host != uprobe->inode ||
-                                                vaddr != vi->vaddr) {
-                        list_del(&vi->probe_list);
-                        kfree(vi);
-                        up_write(&mm->mmap_sem);
-                        mmput(mm);
-                        continue;
-                }
+                                                vaddr != info->vaddr)
+                        goto unlock;
 
-                if (is_register)
-                        ret = install_breakpoint(uprobe, mm, vma, vi->vaddr);
-                else
-                        remove_breakpoint(uprobe, mm, vi->vaddr);
-
-                up_write(&mm->mmap_sem);
-                mmput(mm);
                 if (is_register) {
-                        if (ret && ret == -EEXIST)
-                                ret = 0;
-                        if (ret)
-                                break;
+                        err = install_breakpoint(uprobe, mm, vma, info->vaddr);
+                        if (err == -EEXIST)
+                                err = 0;
+                } else {
+                        remove_breakpoint(uprobe, mm, info->vaddr);
                 }
+ unlock:
+                up_write(&mm->mmap_sem);
+ free:
+                mmput(mm);
+                info = free_map_info(info);
         }
 
-        list_for_each_entry_safe(vi, tmpvi, &try_list, probe_list) {
-                list_del(&vi->probe_list);
-                kfree(vi);
-        }
-
-        return ret;
+        return err;
 }
 
 static int __uprobe_register(struct uprobe *uprobe)