[PATCH] usb: fixup usb so it uses struct pid

The problem with remembering a user space process by its pid is that it is
possible that the process will exit, pid wrap around will occur.
Converting to a struct pid avoid that problem, and paves the way for
implementing a pid namespace.

Also since usb is the only user of kill_proc_info_as_uid rename
kill_proc_info_as_uid to kill_pid_info_as_uid and have the new version take
a struct pid.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/usb/core/devio.c

@@ -65,7 +65,7 @@ DEFINE_MUTEX(usbfs_mutex);
 struct async {
 	struct list_head asynclist;
 	struct dev_state *ps;
-	pid_t pid;
+	struct pid *pid;
 	uid_t uid, euid;
 	unsigned int signr;
 	unsigned int ifnum;
@@ -225,6 +225,7 @@ static struct async *alloc_async(unsigned int numisoframes)
 
 static void free_async(struct async *as)
 {
+	put_pid(as->pid);
 	kfree(as->urb->transfer_buffer);
 	kfree(as->urb->setup_packet);
 	usb_free_urb(as->urb);
@@ -317,7 +318,7 @@ static void async_completed(struct urb *urb, struct pt_regs *regs)
 		sinfo.si_errno = as->urb->status;
 		sinfo.si_code = SI_ASYNCIO;
 		sinfo.si_addr = as->userurb;
-		kill_proc_info_as_uid(as->signr, &sinfo, as->pid, as->uid, 
+		kill_pid_info_as_uid(as->signr, &sinfo, as->pid, as->uid,
 				      as->euid, as->secid);
 	}
 	snoop(&urb->dev->dev, "urb complete\n");
@@ -573,7 +574,7 @@ static int usbdev_open(struct inode *inode, struct file *file)
 	INIT_LIST_HEAD(&ps->async_completed);
 	init_waitqueue_head(&ps->wait);
 	ps->discsignr = 0;
-	ps->disc_pid = current->pid;
+	ps->disc_pid = get_pid(task_pid(current));
 	ps->disc_uid = current->uid;
 	ps->disc_euid = current->euid;
 	ps->disccontext = NULL;
@@ -611,6 +612,7 @@ static int usbdev_release(struct inode *inode, struct file *file)
 	usb_autosuspend_device(dev, 1);
 	usb_unlock_device(dev);
 	usb_put_dev(dev);
+	put_pid(ps->disc_pid);
 	kfree(ps);
 	return 0;
 }
@@ -1063,7 +1065,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 		as->userbuffer = NULL;
 	as->signr = uurb->signr;
 	as->ifnum = ifnum;
-	as->pid = current->pid;
+	as->pid = get_pid(task_pid(current));
 	as->uid = current->uid;
 	as->euid = current->euid;
 	security_task_getsecid(current, &as->secid);

drivers/usb/core/inode.c

@@ -699,7 +699,7 @@ static void usbfs_remove_device(struct usb_device *dev)
 			sinfo.si_errno = EPIPE;
 			sinfo.si_code = SI_ASYNCIO;
 			sinfo.si_addr = ds->disccontext;
-			kill_proc_info_as_uid(ds->discsignr, &sinfo, ds->disc_pid, ds->disc_uid, ds->disc_euid, ds->secid);
+			kill_pid_info_as_uid(ds->discsignr, &sinfo, ds->disc_pid, ds->disc_uid, ds->disc_euid, ds->secid);
 		}
 	}
 }

drivers/usb/core/usb.h

@@ -139,7 +139,7 @@ struct dev_state {
 	struct list_head async_completed;
 	wait_queue_head_t wait;     /* wake up if a request completed */
 	unsigned int discsignr;
-	pid_t disc_pid;
+	struct pid *disc_pid;
 	uid_t disc_uid, disc_euid;
 	void __user *disccontext;
 	unsigned long ifclaimed;

include/linux/sched.h

@@ -1269,12 +1269,12 @@ extern int force_sig_info(int, struct siginfo *, struct task_struct *);
 extern int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp);
 extern int kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp);
 extern int kill_pid_info(int sig, struct siginfo *info, struct pid *pid);
+extern int kill_pid_info_as_uid(int, struct siginfo *, struct pid *, uid_t, uid_t, u32);
 extern int kill_pgrp(struct pid *pid, int sig, int priv);
 extern int kill_pid(struct pid *pid, int sig, int priv);
 extern int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp);
 extern int kill_pg_info(int, struct siginfo *, pid_t);
 extern int kill_proc_info(int, struct siginfo *, pid_t);
-extern int kill_proc_info_as_uid(int, struct siginfo *, pid_t, uid_t, uid_t, u32);
 extern void do_notify_parent(struct task_struct *, int);
 extern void force_sig(int, struct task_struct *);
 extern void force_sig_specific(int, struct task_struct *);

kernel/signal.c

@@ -1136,8 +1136,8 @@ kill_proc_info(int sig, struct siginfo *info, pid_t pid)
 	return error;
 }
 
-/* like kill_proc_info(), but doesn't use uid/euid of "current" */
-int kill_proc_info_as_uid(int sig, struct siginfo *info, pid_t pid,
+/* like kill_pid_info(), but doesn't use uid/euid of "current" */
+int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
 		      uid_t uid, uid_t euid, u32 secid)
 {
 	int ret = -EINVAL;
@@ -1147,7 +1147,7 @@ int kill_proc_info_as_uid(int sig, struct siginfo *info, pid_t pid,
 		return ret;
 
 	read_lock(&tasklist_lock);
-	p = find_task_by_pid(pid);
+	p = pid_task(pid, PIDTYPE_PID);
 	if (!p) {
 		ret = -ESRCH;
 		goto out_unlock;
@@ -1171,7 +1171,7 @@ out_unlock:
 	read_unlock(&tasklist_lock);
 	return ret;
 }
-EXPORT_SYMBOL_GPL(kill_proc_info_as_uid);
+EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
 
 /*
  * kill_something_info() interprets pid in interesting ways just like kill(2).