On Mon, 2011-09-26 at 21:14 +0530, Srikar Dronamraju wrote:

quoted

quoted

+
+/*
+ * Called from mmap_region.
+ * called with mm->mmap_sem acquired.
+ *
+ * Return -ve no if we fail to insert probes and we cannot
+ * bail-out.
+ * Return 0 otherwise. i.e :
+ * - successful insertion of probes
+ * - (or) no possible probes to be inserted.
+ * - (or) insertion of probes failed but we can bail-out.
+ */
+int mmap_uprobe(struct vm_area_struct *vma)
+{
+   struct list_head tmp_list;
+   struct uprobe *uprobe, *u;
+   struct inode *inode;
+   int ret = 0;
+
+   if (!valid_vma(vma))
+           return ret;     /* Bail-out */
+
+   inode = igrab(vma->vm_file->f_mapping->host);
+   if (!inode)
+           return ret;
+
+   INIT_LIST_HEAD(&tmp_list);
+   mutex_lock(&uprobes_mmap_mutex);
+   build_probe_list(inode, &tmp_list);
+   list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
+           loff_t vaddr;
+
+           list_del(&uprobe->pending_list);
+           if (!ret && uprobe->consumers) {
+                   vaddr = vma->vm_start + uprobe->offset;
+                   vaddr -= vma->vm_pgoff << PAGE_SHIFT;
+                   if (vaddr < vma->vm_start || vaddr >= vma->vm_end)
+                           continue;
+                   ret = install_breakpoint(vma->vm_mm, uprobe);
+
+                   if (ret && (ret == -ESRCH || ret == -EEXIST))
+                           ret = 0;
+           }
+           put_uprobe(uprobe);
+   }
+
+   mutex_unlock(&uprobes_mmap_mutex);
+   iput(inode);
+   return ret;
+}
+
+static void dec_mm_uprobes_count(struct vm_area_struct *vma,
+           struct inode *inode)
+{
+   struct uprobe *uprobe;
+   struct rb_node *n;
+   unsigned long flags;
+
+   n = uprobes_tree.rb_node;
+   spin_lock_irqsave(&uprobes_treelock, flags);
+   uprobe = __find_uprobe(inode, 0, &n);
+
+   /*
+    * If indeed there is a probe for the inode and with offset zero,
+    * then lets release its reference. (ref got thro __find_uprobe)
+    */
+   if (uprobe)
+           put_uprobe(uprobe);
+   for (; n; n = rb_next(n)) {
+           loff_t vaddr;
+
+           uprobe = rb_entry(n, struct uprobe, rb_node);
+           if (uprobe->inode != inode)
+                   break;
+           vaddr = vma->vm_start + uprobe->offset;
+           vaddr -= vma->vm_pgoff << PAGE_SHIFT;
+           if (vaddr < vma->vm_start || vaddr >= vma->vm_end)
+                   continue;
+           atomic_dec(&vma->vm_mm->mm_uprobes_count);
+   }
+   spin_unlock_irqrestore(&uprobes_treelock, flags);
+}
+
+/*
+ * Called in context of a munmap of a vma.
+ */
+void munmap_uprobe(struct vm_area_struct *vma)
+{
+   struct inode *inode;
+
+   if (!valid_vma(vma))
+           return;         /* Bail-out */
+
+   if (!atomic_read(&vma->vm_mm->mm_uprobes_count))
+           return;
+
+   inode = igrab(vma->vm_file->f_mapping->host);
+   if (!inode)
+           return;
+
+   dec_mm_uprobes_count(vma, inode);
+   iput(inode);
+   return;
+}

One has to wonder why mmap_uprobe() can be one function but
munmap_uprobe() cannot.

I didnt understand this comment, Can you please elaborate?
mmap_uprobe uses build_probe_list and munmap_uprobe uses
dec_mm_uprobes_count. 

Ah, I missed build_probe_list(), but I didn't see a reason for the
existence of dec_mm_uprobe_count(), the name doesn't make sense and the
content is 'small' enough to just put in munmap_uprobe.

To me it looks similar to the list iteration you have in mmap_uprobe(),
you didn't split that out into another function either.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>