RE: Review patches of user space kprobe

["Zhang, Yanmin" <yanmin.zhang@intel.com>]

>>-----Original Message-----
>>From: systemtap-owner@sourceware.org [mailto:systemtap-owner@sourceware.org] On Behalf Of Zhang, Yanmin
>>Sent: 2006年1月6日 10:52
>>To: prasanna@in.ibm.com
>>Cc: systemtap@sources.redhat.com; Keshavamurthy, Anil S; Mao, Bibo
>>Subject: RE: Review patches of user space kprobe
>>
>>>>-----Original Message-----
>>>>From: systemtap-owner@sourceware.org [mailto:systemtap-owner@sourceware.org] On Behalf Of Prasanna S Panchamukhi
>>>>Sent: 2006年1月5日 19:14
>>>>To: Zhang, Yanmin
>>>>Cc: systemtap@sources.redhat.com; Keshavamurthy, Anil S; Mao, Bibo
>>>>Subject: Re: Review patches of user space kprobe
>>>>
>>>>> >>+ */
>>>>> >>+static struct kprobe *get_uprobe_at(struct inode *inode, unsigned
>>>>> long offset)
>>>>> >>+{
>>>>> >>+	struct hlist_head *head;
>>>>> >>+	struct hlist_node *node;
>>>>> >>+	struct kprobe *p;
>>>>> >>+
>>>>> >>+	head = &kprobe_table[hash_long((unsigned long)inode * offset,
>>>>> >>+				       KPROBE_HASH_BITS)];
>>>>> >>+	hlist_for_each_entry(p, node, head, hlist) {
>>>>> >>+		if (p->pre_handler == aggr_pre_handler)
>>>>> >>+			return p;
>>>>> >>+		else {
>>>>> >>+			struct uprobe *user = container_of(p,
>>>>> >>+							struct uprobe,
>>>>> kp);
>>>>> Kprobe and uprobe share the same hash table. Does p here always point to
>>>>> uprobe?
>>>>
>>>>Check can be made before accessig uprobe.
>>>>if (!kernel_text_address((unsigned long)p->addr))
>>Incorrect. get_uprobe, the caller of get_uprobe_at, might be crazy. current_uprobe might be set as up and get_user_page(up) is called
>>incorrectly. The logic is *not clear*.
I might misunderstand your reply. If put the check before using container_of in function get_uprobe_at, the issue could be resolved.