trace: stop all recording to ring buffer on ftrace_dump

[safe/jmp/linux-2.6] / kernel / acct.c

diff --git a/kernel/acct.c b/kernel/acct.c
index 0feba97..7afa315 100644 (file)
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -277,7 +277,7 @@ static int acct_on(char *name)
  * should be written. If the filename is NULL, accounting will be
  * shutdown.
  */
-asmlinkage long sys_acct(const char __user *name)
+SYSCALL_DEFINE1(acct, const char __user *, name)
 {
        int error;
 
@@ -530,15 +530,14 @@ static void do_acct_process(struct bsd_acct_struct *acct,
        do_div(elapsed, AHZ);
        ac.ac_btime = get_seconds() - elapsed;
        /* we really need to bite the bullet and change layout */
-       ac.ac_uid = current->uid;
-       ac.ac_gid = current->gid;
+       current_uid_gid(&ac.ac_uid, &ac.ac_gid);
 #if ACCT_VERSION==2
        ac.ac_ahz = AHZ;
 #endif
 #if ACCT_VERSION==1 || ACCT_VERSION==2
        /* backward-compatible 16 bit fields */
-       ac.ac_uid16 = current->uid;
-       ac.ac_gid16 = current->gid;
+       ac.ac_uid16 = ac.ac_uid;
+       ac.ac_gid16 = ac.ac_gid;
 #endif
 #if ACCT_VERSION==3
        ac.ac_pid = task_tgid_nr_ns(current, ns);
@@ -548,7 +547,7 @@ static void do_acct_process(struct bsd_acct_struct *acct,
 #endif
 
        spin_lock_irq(&current->sighand->siglock);
-       tty = current->signal->tty;
+       tty = current->signal->tty;     /* Safe as we hold the siglock */
        ac.ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
        ac.ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime)));
        ac.ac_stime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_stime)));
@@ -657,7 +656,8 @@ static void acct_process_in_ns(struct pid_namespace *ns)
 }
 
 /**
- * acct_process - now just a wrapper around do_acct_process
+ * acct_process - now just a wrapper around acct_process_in_ns,
+ * which in turn is a wrapper around do_acct_process.
  *
  * handles process accounting for an exiting task
  */
@@ -665,6 +665,11 @@ void acct_process(void)
 {
        struct pid_namespace *ns;
 
+       /*
+        * This loop is safe lockless, since current is still
+        * alive and holds its namespace, which in turn holds
+        * its parent.
+        */
        for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent)
                acct_process_in_ns(ns);
 }