[PATCH] hide-threads-2.5.34-C1

I fixed up the 'remove thread group inferiors from the tasklist' patch. I
think i managed to find a reasonably good construct to iterate over all
threads:

	do_each_thread(g, p) {
		...
	} while_each_thread(g, p);

the only caveat with this is that the construct suggests a single-loop -
while it's two loops internally - and 'break' will not work. I added a
comment to sched.h that warns about this, but perhaps it would help more
to have naming that suggests two loops:

	for_each_process_do_each_thread(g, p) {
		...
	} while_each_thread(g, p);

but this looks a bit too long. I dont know. We might as well use it all
unrolled and no helper macros - although with the above construct it's
pretty straightforward to iterate over all threads in the system.

arch/i386/kernel/vm86.c

@@ -608,16 +608,17 @@ static inline void free_vm86_irq(int irqnumber)
 
 static inline int task_valid(struct task_struct *tsk)
 {
-	struct task_struct *p;
+	struct task_struct *g, *p;
 	int ret = 0;
 
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	do_each_thread(g, p)
 		if ((p == tsk) && (p->sig)) {
 			ret = 1;
-			break;
+			goto out;
 		}
-	}
+	while_each_thread(g, p);
+out:
 	read_unlock(&tasklist_lock);
 	return ret;
 }

drivers/char/sysrq.c

@@ -299,7 +299,7 @@ static void send_sig_all(int sig)
 {
 	struct task_struct *p;
 
-	for_each_task(p) {
+	for_each_process(p) {
 		if (p->mm && p->pid != 1)
 			/* Not swapper, init nor kernel thread */
 			force_sig(sig, p);

drivers/char/tty_io.c

@@ -496,7 +496,7 @@ void do_tty_hangup(void *data)
 	}
 	
 	read_lock(&tasklist_lock);
- 	for_each_task(p) {
+ 	for_each_process(p) {
 		if ((tty->session > 0) && (p->session == tty->session) &&
 		    p->leader) {
 			send_sig(SIGHUP,p,1);
@@ -598,7 +598,7 @@ void disassociate_ctty(int on_exit)
 	tty->pgrp = -1;
 
 	read_lock(&tasklist_lock);
-	for_each_task(p)
+	for_each_process(p)
 	  	if (p->session == current->session)
 			p->tty = NULL;
 	read_unlock(&tasklist_lock);
@@ -1223,7 +1223,7 @@ static void release_dev(struct file * filp)
 		struct task_struct *p;
 
 		read_lock(&tasklist_lock);
-		for_each_task(p) {
+		for_each_process(p) {
 			if (p->tty == tty || (o_tty && p->tty == o_tty))
 				p->tty = NULL;
 		}
@@ -1561,7 +1561,7 @@ static int tiocsctty(struct tty_struct *tty, int arg)
 			struct task_struct *p;
 
 			read_lock(&tasklist_lock);
-			for_each_task(p)
+			for_each_process(p)
 				if (p->tty == tty)
 					p->tty = NULL;
 			read_unlock(&tasklist_lock);
@@ -1834,7 +1834,7 @@ static void __do_SAK(void *arg)
 	if (tty->driver.flush_buffer)
 		tty->driver.flush_buffer(tty);
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	for_each_process(p) {
 		if ((p->tty == tty) ||
 		    ((session > 0) && (p->session == session))) {
 			printk(KERN_NOTICE "SAK: killed process %d"

fs/fcntl.c

@@ -493,7 +493,7 @@ void send_sigio(struct fown_struct *fown, int fd, int band)
 		send_sigio_to_task(p, fown, fd, band);
 		goto out_unlock_task;
 	}
-	for_each_task(p) {
+	for_each_process(p) {
 		int match = p->pid;
 		if (pid < 0)
 			match = -p->pgrp;
@@ -531,7 +531,7 @@ int send_sigurg(struct fown_struct *fown)
 		send_sigurg_to_task(p, fown);
 		goto out_unlock_task;
 	}
-	for_each_task(p) {
+	for_each_process(p) {
 		int match = p->pid;
 		if (pid < 0)
 			match = -p->pgrp;

fs/namespace.c

@@ -883,11 +883,11 @@ asmlinkage long sys_mount(char * dev_name, char * dir_name, char * type,
 
 static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
 {
-	struct task_struct *p;
+	struct task_struct *g, *p;
 	struct fs_struct *fs;
 
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	do_each_thread(g, p) {
 		task_lock(p);
 		fs = p->fs;
 		if (fs) {
@@ -900,7 +900,7 @@ static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
 			put_fs_struct(fs);
 		} else
 			task_unlock(p);
-	}
+	} while_each_thread(g, p);
 	read_unlock(&tasklist_lock);
 }
 
@@ -1012,7 +1012,7 @@ static void __init init_mount_tree(void)
 {
 	struct vfsmount *mnt;
 	struct namespace *namespace;
-	struct task_struct *p;
+	struct task_struct *g, *p;
 
 	mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
 	if (IS_ERR(mnt))
@@ -1028,10 +1028,10 @@ static void __init init_mount_tree(void)
 
 	init_task.namespace = namespace;
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	do_each_thread(g, p) {
 		get_namespace(namespace);
 		p->namespace = namespace;
-	}
+	} while_each_thread(g, p);
 	read_unlock(&tasklist_lock);
 
 	set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root);

fs/proc/base.c

@@ -1136,7 +1136,7 @@ static int get_pid_list(int index, unsigned int *pids)
 
 	index--;
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	for_each_process(p) {
 		int pid = p->pid;
 		if (!pid)
 			continue;

fs/proc/inode.c

@@ -235,7 +235,9 @@ int proc_fill_super(struct super_block *s, void *data, int silent)
 	 * Fixup the root inode's nlink value
 	 */
 	read_lock(&tasklist_lock);
-	for_each_task(p) if (p->pid) root_inode->i_nlink++;
+	for_each_process(p)
+		if (p->pid)
+			root_inode->i_nlink++;
 	read_unlock(&tasklist_lock);
 	s->s_root = d_alloc_root(root_inode);
 	if (!s->s_root)

include/linux/sched.h

@@ -760,14 +760,16 @@ static inline void remove_wait_queue_locked(wait_queue_head_t *q,
 #define remove_parent(p)	list_del_init(&(p)->sibling)
 #define add_parent(p, parent)	list_add_tail(&(p)->sibling,&(parent)->children)
 
-#define REMOVE_LINKS(p) do {				\
-	list_del_init(&(p)->tasks);			\
-	remove_parent(p);				\
+#define REMOVE_LINKS(p) do {					\
+	if (thread_group_leader(p))				\
+		list_del_init(&(p)->tasks);			\
+	remove_parent(p);					\
 	} while (0)
 
-#define SET_LINKS(p) do {				\
-	list_add_tail(&(p)->tasks,&init_task.tasks);	\
-	add_parent(p, (p)->parent);			\
+#define SET_LINKS(p) do {					\
+	if (thread_group_leader(p))				\
+		list_add_tail(&(p)->tasks,&init_task.tasks);	\
+	add_parent(p, (p)->parent);				\
 	} while (0)
 
 static inline struct task_struct *eldest_child(struct task_struct *p)
@@ -797,11 +799,18 @@ static inline struct task_struct *younger_sibling(struct task_struct *p)
 #define next_task(p)	list_entry((p)->tasks.next, struct task_struct, tasks)
 #define prev_task(p)	list_entry((p)->tasks.prev, struct task_struct, tasks)
 
-#define for_each_task(p) \
+#define for_each_process(p) \
 	for (p = &init_task ; (p = next_task(p)) != &init_task ; )
 
-#define for_each_thread(task) \
-	for (task = next_thread(current) ; task != current ; task = next_thread(task))
+/*
+ * Careful: do_each_thread/while_each_thread is a double loop so
+ *          'break' will not work as expected - use goto instead.
+ */
+#define do_each_thread(g, t) \
+	for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
+
+#define while_each_thread(g, t) \
+	while ((t = next_thread(t)) != g)
 
 static inline task_t *next_thread(task_t *p)
 {

kernel/capability.c

@@ -83,13 +83,13 @@ static inline void cap_set_pg(int pgrp, kernel_cap_t *effective,
 			      kernel_cap_t *inheritable,
 			      kernel_cap_t *permitted)
 {
-     task_t *target;
+     task_t *g, *target;
 
-     for_each_task(target) {
+     do_each_thread(g, target) {
              if (target->pgrp != pgrp)
                      continue;
 	     security_ops->capset_set(target, effective, inheritable, permitted);
-     }
+     } while_each_thread(g, target);
 }
 
 /*
@@ -100,13 +100,13 @@ static inline void cap_set_all(kernel_cap_t *effective,
 			       kernel_cap_t *inheritable,
 			       kernel_cap_t *permitted)
 {
-     task_t *target;
+     task_t *g, *target;
 
-     for_each_task(target) {
+     do_each_thread(g, target) {
              if (target == current || target->pid == 1)
                      continue;
 	     security_ops->capset_set(target, effective, inheritable, permitted);
-     }
+     } while_each_thread(g, target);
 }
 
 /*

kernel/exit.c

@@ -115,7 +115,7 @@ int session_of_pgrp(int pgrp)
 
 	fallback = -1;
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	for_each_process(p) {
  		if (p->session <= 0)
  			continue;
 		if (p->pgrp == pgrp) {
@@ -141,7 +141,7 @@ static int __will_become_orphaned_pgrp(int pgrp, struct task_struct * ignored_ta
 {
 	struct task_struct *p;
 
-	for_each_task(p) {
+	for_each_process(p) {
 		if ((p == ignored_task) || (p->pgrp != pgrp) ||
 		    (p->state == TASK_ZOMBIE) ||
 		    (p->parent->pid == 1))
@@ -175,7 +175,7 @@ static inline int __has_stopped_jobs(int pgrp)
 	int retval = 0;
 	struct task_struct * p;
 
-	for_each_task(p) {
+	for_each_process(p) {
 		if (p->pgrp != pgrp)
 			continue;
 		if (p->state != TASK_STOPPED)

kernel/fork.c

@@ -161,7 +161,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 
 static int get_pid(unsigned long flags)
 {
-	struct task_struct *p;
+	struct task_struct *g, *p;
 	int pid;
 
 	if (flags & CLONE_IDLETASK)
@@ -178,7 +178,7 @@ static int get_pid(unsigned long flags)
 		next_safe = pid_max;
 		read_lock(&tasklist_lock);
 	repeat:
-		for_each_task(p) {
+		do_each_thread(g, p) {
 			if (p->pid == last_pid	||
 			   p->pgrp == last_pid	||
 			   p->session == last_pid) {
@@ -195,7 +195,8 @@ static int get_pid(unsigned long flags)
 				next_safe = p->pgrp;
 			if (p->session > last_pid && next_safe > p->session)
 				next_safe = p->session;
-		}
+		} while_each_thread(g, p);
+
 		read_unlock(&tasklist_lock);
 	}
 	pid = last_pid;

kernel/sched.c

@@ -1838,7 +1838,7 @@ char * render_sigset_t(sigset_t *set, char *buffer)
 
 void show_state(void)
 {
-	task_t *p;
+	task_t *g, *p;
 
 #if (BITS_PER_LONG == 32)
 	printk("\n"
@@ -1850,14 +1850,15 @@ void show_state(void)
 	printk("  task                 PC        stack   pid father child younger older\n");
 #endif
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	do_each_thread(g, p) {
 		/*
 		 * reset the NMI-timeout, listing all files on a slow
 		 * console might take alot of time:
 		 */
 		touch_nmi_watchdog();
 		show_task(p);
-	}
+	} while_each_thread(g, p);
+
 	read_unlock(&tasklist_lock);
 }
 

kernel/signal.c

@@ -938,8 +938,8 @@ int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
 		struct task_struct *p;
 
 		retval = -ESRCH;
-		for_each_task(p) {
-			if (p->pgrp == pgrp && thread_group_leader(p)) {
+		for_each_process(p) {
+			if (p->pgrp == pgrp) {
 				int err = send_sig_info(sig, info, p);
 				if (retval)
 					retval = err;
@@ -976,7 +976,7 @@ kill_sl_info(int sig, struct siginfo *info, pid_t sess)
 
 		retval = -ESRCH;
 		read_lock(&tasklist_lock);
-		for_each_task(p) {
+		for_each_process(p) {
 			if (p->leader && p->session == sess) {
 				int err = send_sig_info(sig, info, p);
 				if (retval)
@@ -1020,8 +1020,8 @@ static int kill_something_info(int sig, struct siginfo *info, int pid)
 		struct task_struct * p;
 
 		read_lock(&tasklist_lock);
-		for_each_task(p) {
-			if (p->pid > 1 && p != current && thread_group_leader(p)) {
+		for_each_process(p) {
+			if (p->pid > 1 && p != current) {
 				int err = send_sig_info(sig, info, p);
 				++count;
 				if (err != -EPERM)

kernel/suspend.c

@@ -204,14 +204,14 @@ void refrigerator(unsigned long flag)
 int freeze_processes(void)
 {
 	int todo, start_time;
-	struct task_struct *p;
+	struct task_struct *g, *p;
 	
 	printk( "Stopping tasks: " );
 	start_time = jiffies;
 	do {
 		todo = 0;
 		read_lock(&tasklist_lock);
-		for_each_task(p) {
+		do_each_thread(g, p) {
 			unsigned long flags;
 			INTERESTING(p);
 			if (p->flags & PF_FROZEN)
@@ -224,7 +224,7 @@ int freeze_processes(void)
 			signal_wake_up(p);
 			spin_unlock_irqrestore(&p->sigmask_lock, flags);
 			todo++;
-		}
+		} while_each_thread(g, p);
 		read_unlock(&tasklist_lock);
 		yield();
 		if (time_after(jiffies, start_time + TIMEOUT)) {
@@ -240,18 +240,19 @@ int freeze_processes(void)
 
 void thaw_processes(void)
 {
-	struct task_struct *p;
+	struct task_struct *g, *p;
 
 	printk( "Restarting tasks..." );
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	do_each_thread(g, p) {
 		INTERESTING(p);
 		
 		if (p->flags & PF_FROZEN) p->flags &= ~PF_FROZEN;
 		else
 			printk(KERN_INFO " Strange, %s not stopped\n", p->comm );
 		wake_up_process(p);
-	}
+	} while_each_thread(g, p);
+
 	read_unlock(&tasklist_lock);
 	printk( " done\n" );
 	MDELAY(500);

kernel/sys.c

@@ -227,7 +227,7 @@ static int proc_sel(struct task_struct *p, int which, int who)
 
 asmlinkage long sys_setpriority(int which, int who, int niceval)
 {
-	struct task_struct *p;
+	struct task_struct *g, *p;
 	int error;
 
 	if (which > 2 || which < 0)
@@ -241,7 +241,7 @@ asmlinkage long sys_setpriority(int which, int who, int niceval)
 		niceval = 19;
 
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	do_each_thread(g, p) {
 		int no_nice;
 		if (!proc_sel(p, which, who))
 			continue;
@@ -262,8 +262,8 @@ asmlinkage long sys_setpriority(int which, int who, int niceval)
 			continue;
 		}
 		set_user_nice(p, niceval);
+	} while_each_thread(g, p);
 
-	}
 	read_unlock(&tasklist_lock);
 
 	return error;
@@ -277,21 +277,21 @@ asmlinkage long sys_setpriority(int which, int who, int niceval)
  */
 asmlinkage long sys_getpriority(int which, int who)
 {
-	struct task_struct *p;
+	struct task_struct *g, *p;
 	long retval = -ESRCH;
 
 	if (which > 2 || which < 0)
 		return -EINVAL;
 
 	read_lock(&tasklist_lock);
-	for_each_task (p) {
+	do_each_thread(g, p) {
 		long niceval;
 		if (!proc_sel(p, which, who))
 			continue;
 		niceval = 20 - task_nice(p);
 		if (niceval > retval)
 			retval = niceval;
-	}
+	} while_each_thread(g, p);
 	read_unlock(&tasklist_lock);
 
 	return retval;
@@ -882,12 +882,12 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
 	if (p->leader)
 		goto out;
 	if (pgid != pid) {
-		struct task_struct * tmp;
-		for_each_task (tmp) {
+		struct task_struct *g, *tmp;
+		do_each_thread(g, tmp) {
 			if (tmp->pgrp == pgid &&
 			    tmp->session == current->session)
 				goto ok_pgid;
-		}
+		} while_each_thread(g, tmp);
 		goto out;
 	}
 
@@ -956,14 +956,14 @@ asmlinkage long sys_getsid(pid_t pid)
 
 asmlinkage long sys_setsid(void)
 {
-	struct task_struct * p;
+	struct task_struct *g, *p;
 	int err = -EPERM;
 
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	do_each_thread(g, p)
 		if (p->pgrp == current->pid)
 			goto out;
-	}
+	while_each_thread(g, p);
 
 	current->leader = 1;
 	current->session = current->pgrp = current->pid;

mm/oom_kill.c

@@ -116,10 +116,10 @@ static int badness(struct task_struct *p)
 static struct task_struct * select_bad_process(void)
 {
 	int maxpoints = 0;
-	struct task_struct *p = NULL;
+	struct task_struct *g, *p;
 	struct task_struct *chosen = NULL;
 
-	for_each_task(p) {
+	do_each_thread(g, p)
 		if (p->pid) {
 			int points = badness(p);
 			if (points > maxpoints) {
@@ -127,7 +127,7 @@ static struct task_struct * select_bad_process(void)
 				maxpoints = points;
 			}
 		}
-	}
+	while_each_thread(g, p);
 	return chosen;
 }
 
@@ -166,7 +166,7 @@ void oom_kill_task(struct task_struct *p)
  */
 static void oom_kill(void)
 {
-	struct task_struct *p, *q;
+	struct task_struct *g, *p, *q;
 	
 	read_lock(&tasklist_lock);
 	p = select_bad_process();
@@ -176,9 +176,11 @@ static void oom_kill(void)
 		panic("Out of memory and no killable processes...\n");
 
 	/* kill all processes that share the ->mm (i.e. all threads) */
-	for_each_task(q) {
-		if(q->mm == p->mm) oom_kill_task(q);
-	}
+	do_each_thread(g, q)
+		if (q->mm == p->mm)
+			oom_kill_task(q);
+	while_each_thread(g, q);
+
 	read_unlock(&tasklist_lock);
 
 	/*

net/ipv4/netfilter/ipt_owner.c

@@ -14,12 +14,12 @@
 static int
 match_comm(const struct sk_buff *skb, const char *comm)
 {
-	struct task_struct *p;
+	struct task_struct *g, *p;
 	struct files_struct *files;
 	int i;
 
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	do_each_thread(g, p) {
 		if(strncmp(p->comm, comm, sizeof(p->comm)))
 			continue;
 
@@ -38,7 +38,7 @@ match_comm(const struct sk_buff *skb, const char *comm)
 			read_unlock(&files->file_lock);
 		}
 		task_unlock(p);
-	}
+	} while_each_thread(g, p);
 	read_unlock(&tasklist_lock);
 	return 0;
 }
@@ -77,12 +77,12 @@ match_pid(const struct sk_buff *skb, pid_t pid)
 static int
 match_sid(const struct sk_buff *skb, pid_t sid)
 {
-	struct task_struct *p;
+	struct task_struct *g, *p;
 	struct file *file = skb->sk->socket->file;
 	int i, found=0;
 
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	do_each_thread(g, p) {
 		struct files_struct *files;
 		if (p->session != sid)
 			continue;
@@ -100,9 +100,10 @@ match_sid(const struct sk_buff *skb, pid_t sid)
 			read_unlock(&files->file_lock);
 		}
 		task_unlock(p);
-		if(found)
-			break;
-	}
+		if (found)
+			goto out;
+	} while_each_thread(g, p);
+out:
 	read_unlock(&tasklist_lock);
 
 	return found;

net/ipv6/netfilter/ip6t_owner.c

@@ -49,12 +49,12 @@ match_pid(const struct sk_buff *skb, pid_t pid)
 static int
 match_sid(const struct sk_buff *skb, pid_t sid)
 {
-	struct task_struct *p;
+	struct task_struct *g, *p;
 	struct file *file = skb->sk->socket->file;
 	int i, found=0;
 
 	read_lock(&tasklist_lock);
-	for_each_task(p) {
+	do_each_thread(g, p) {
 		struct files_struct *files;
 		if (p->session != sid)
 			continue;
@@ -72,9 +72,10 @@ match_sid(const struct sk_buff *skb, pid_t sid)
 			read_unlock(&files->file_lock);
 		}
 		task_unlock(p);
-		if(found)
-			break;
-	}
+		if (found)
+			goto out;
+	} while_each_thread(g, p);
+out:
 	read_unlock(&tasklist_lock);
 
 	return found;