[PATCH 3/5] pid: Implement kill_tref.

[Eric W. Biederman]

Currently most functions for sending a signal to
a task or group of tasks take a pid as an argoument.
kill_ref instead takes a task_ref.  I would use a
function that simply takes a task but the tasklist_lock
must be taken to ensure that there is not a race in
derferencing task_ref->task.

kill_tref can stand in for either kill_proc, or kill_pg
depending on the type of the reference.

Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>


---

 include/linux/sched.h |    3 +++
 kernel/signal.c       |   31 +++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 0 deletions(-)

2d2627206f44ce032e521705efb5f712d440ba13
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 12f3cc5..8cd8075 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1109,6 +1109,9 @@ extern int send_sig_info(int, struct sig
 extern int send_group_sig_info(int, struct siginfo *, struct task_struct *);
 extern int force_sigsegv(int, struct task_struct *);
 extern int force_sig_info(int, struct siginfo *, struct task_struct *);
+extern int __kill_tref_info(int sig, struct siginfo *info, struct task_ref *ref);
+extern int kill_tref_info(int sig, struct siginfo *info, struct task_ref *ref);
+extern int kill_tref(struct task_ref *ref, 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);
diff --git a/kernel/signal.c b/kernel/signal.c
index d3efafd..20a67ae 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1146,6 +1146,32 @@ retry:
 	return ret;
 }
 
+int __kill_tref_info(int sig, struct siginfo *info, struct task_ref *ref)
+{
+	struct task_struct *p = ref->task;
+	int retval, success;
+
+	success = 0;
+	retval = -ESRCH;
+	do_each_task(p, ref->type) {
+		int err = group_send_sig_info(sig, info, p);
+		success |= !err;
+		retval = err;
+	} while_each_task(p, ref->type);
+	return success ? 0 : retval;
+}
+
+int kill_tref_info(int sig, struct siginfo *info, struct task_ref *ref)
+{
+	int retval;
+
+	read_lock(&tasklist_lock);
+	retval = __kill_tref_info(sig, info, ref);
+	read_unlock(&tasklist_lock);
+
+	return retval;
+}
+
 /*
  * kill_pg_info() sends a signal to a process group: this is what the tty
  * control characters do (^C, ^Z etc)
@@ -1365,6 +1391,11 @@ kill_proc(pid_t pid, int sig, int priv)
 	return kill_proc_info(sig, __si_special(priv), pid);
 }
 
+int kill_tref(struct task_ref *ref, int sig, int priv)
+{
+	return kill_tref_info(sig, __si_special(priv), ref);
+}
+
 /*
  * These functions support sending signals using preallocated sigqueue
  * structures.  This is needed "because realtime applications cannot
-- 
1.1.5.g3480

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