From f6b98c1cbc925f082a0d5d6e58d422bf1f6ca85e Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Mon, 6 Aug 2012 13:15:09 +0200
Subject: [PATCH] --- yaml --- r: 323738 b: refs/heads/master c:
 647c42dfd40fec032a4c8525a755160f0765921f h: refs/heads/master v: v3

---
 [refs]                        |  2 +-
 trunk/include/linux/uprobes.h |  2 +-
 trunk/kernel/events/uprobes.c | 38 ++---------------------------------
 3 files changed, 4 insertions(+), 38 deletions(-)

diff --git a/[refs] b/[refs]
index 7f02f2991a33..8d3c0f042171 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8bd874456e2ec49b9e64372ddc89a6f88901d184
+refs/heads/master: 647c42dfd40fec032a4c8525a755160f0765921f
diff --git a/trunk/include/linux/uprobes.h b/trunk/include/linux/uprobes.h
index efe4b3308c74..03ae547c1c31 100644
--- a/trunk/include/linux/uprobes.h
+++ b/trunk/include/linux/uprobes.h
@@ -99,8 +99,8 @@ struct xol_area {
 
 struct uprobes_state {
 	struct xol_area		*xol_area;
-	atomic_t		count;
 };
+
 extern int __weak set_swbp(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr);
 extern int __weak set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm,  unsigned long vaddr, bool verify);
 extern bool __weak is_swbp_insn(uprobe_opcode_t *insn);
diff --git a/trunk/kernel/events/uprobes.c b/trunk/kernel/events/uprobes.c
index 0cefde276641..6f1664d217dc 100644
--- a/trunk/kernel/events/uprobes.c
+++ b/trunk/kernel/events/uprobes.c
@@ -678,18 +678,7 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
 		uprobe->flags |= UPROBE_COPY_INSN;
 	}
 
-	/*
-	 * Ideally, should be updating the probe count after the breakpoint
-	 * has been successfully inserted. However a thread could hit the
-	 * breakpoint we just inserted even before the probe count is
-	 * incremented. If this is the first breakpoint placed, breakpoint
-	 * notifier might ignore uprobes and pass the trap to the thread.
-	 * Hence increment before and decrement on failure.
-	 */
-	atomic_inc(&mm->uprobes_state.count);
 	ret = set_swbp(&uprobe->arch, mm, vaddr);
-	if (ret)
-		atomic_dec(&mm->uprobes_state.count);
 
 	return ret;
 }
@@ -697,8 +686,7 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
 static void
 remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr)
 {
-	if (!set_orig_insn(&uprobe->arch, mm, vaddr, true))
-		atomic_dec(&mm->uprobes_state.count);
+	set_orig_insn(&uprobe->arch, mm, vaddr, true);
 }
 
 /*
@@ -1051,13 +1039,6 @@ int uprobe_mmap(struct vm_area_struct *vma)
 
 				if (!is_swbp_at_addr(vma->vm_mm, vaddr))
 					continue;
-
-				/*
-				 * Unable to insert a breakpoint, but
-				 * breakpoint lies underneath. Increment the
-				 * probe count.
-				 */
-				atomic_inc(&vma->vm_mm->uprobes_state.count);
 			}
 
 			if (!ret)
@@ -1068,9 +1049,6 @@ int uprobe_mmap(struct vm_area_struct *vma)
 
 	mutex_unlock(uprobes_mmap_hash(inode));
 
-	if (ret)
-		atomic_sub(count, &vma->vm_mm->uprobes_state.count);
-
 	return ret;
 }
 
@@ -1089,9 +1067,6 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
 	if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */
 		return;
 
-	if (!atomic_read(&vma->vm_mm->uprobes_state.count))
-		return;
-
 	inode = vma->vm_file->f_mapping->host;
 	if (!inode)
 		return;
@@ -1100,13 +1075,6 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
 	build_probe_list(inode, vma, start, end, &tmp_list);
 
 	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
-		unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);
-		/*
-		 * An unregister could have removed the probe before
-		 * unmap. So check before we decrement the count.
-		 */
-		if (is_swbp_at_addr(vma->vm_mm, vaddr) == 1)
-			atomic_dec(&vma->vm_mm->uprobes_state.count);
 		put_uprobe(uprobe);
 	}
 	mutex_unlock(uprobes_mmap_hash(inode));
@@ -1217,7 +1185,6 @@ void uprobe_clear_state(struct mm_struct *mm)
 void uprobe_reset_state(struct mm_struct *mm)
 {
 	mm->uprobes_state.xol_area = NULL;
-	atomic_set(&mm->uprobes_state.count, 0);
 }
 
 /*
@@ -1585,8 +1552,7 @@ int uprobe_pre_sstep_notifier(struct pt_regs *regs)
 {
 	struct uprobe_task *utask;
 
-	if (!current->mm || !atomic_read(&current->mm->uprobes_state.count))
-		/* task is currently not uprobed */
+	if (!current->mm)
 		return 0;
 
 	utask = current->utask;