[PATCH] kernel/exit.c: call read_unlock() when failure occurs after already called read_lock() in do_wait().

[Chen Gang]

If failure occurs after called read_lock(), need call read_unlock() too.

It can fail in multiple position, so add new tag 'fail_lock' for it
(also can let 'if' only content one jump statement).


Signed-off-by: Chen Gang <gang.c...@asianux.com>
---
 kernel/exit.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index a949819..3da5476 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1527,11 +1527,11 @@ repeat:
        do {
                retval = do_wait_thread(wo, tsk);
                if (retval)
-                       goto end;
+                       goto fail_lock;
 
                retval = ptrace_do_wait(wo, tsk);
                if (retval)
-                       goto end;
+                       goto fail_lock;
 
                if (wo->wo_flags & __WNOTHREAD)
                        break;
@@ -1551,6 +1551,10 @@ end:
        __set_current_state(TASK_RUNNING);
        remove_wait_queue(&current->signal->wait_chldexit, &wo->child_wait);
        return retval;
+
+fail_lock:
+       read_unlock(&tasklist_lock);
+       goto end;
 }
 
 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
-- 
1.7.7.6
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