[PATCH] coredump: some code relocations

This is a preparation for the next patch.  No functional changes.
Basically, this patch moves '->flags & SIGNAL_GROUP_EXIT' check into
zap_threads(), and 'complete(vfork_done)' into coredump_wait outside of
->mmap_sem protected area.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 40 insertions, 30 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 49fa0127a330..8c8f2894949d 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1393,20 +1393,22 @@ static void zap_process(struct task_struct *start)
         unlock_task_sighand(start, &flags);
 }
 
-static void zap_threads(struct mm_struct *mm)
+static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
+                                int exit_code)
 {
         struct task_struct *g, *p;
-        struct task_struct *tsk = current;
-        struct completion *vfork_done = tsk->vfork_done;
-
-        /*
-         * Make sure nobody is waiting for us to release the VM,
-         * otherwise we can deadlock when we wait on each other
-         */
-        if (vfork_done) {
-                tsk->vfork_done = NULL;
-                complete(vfork_done);
+        int err = -EAGAIN;
+
+        spin_lock_irq(&tsk->sighand->siglock);
+        if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
+                tsk->signal->flags = SIGNAL_GROUP_EXIT;
+                tsk->signal->group_exit_code = exit_code;
+                tsk->signal->group_stop_count = 0;
+                err = 0;
         }
+        spin_unlock_irq(&tsk->sighand->siglock);
+        if (err)
+                return err;
 
         rcu_read_lock();
         for_each_process(g) {
@@ -1420,22 +1422,43 @@ static void zap_threads(struct mm_struct *mm)
                 } while ((p = next_thread(p)) != g);
         }
         rcu_read_unlock();
+
+        return mm->core_waiters;
 }
 
-static void coredump_wait(struct mm_struct *mm)
+static int coredump_wait(int exit_code)
 {
-        DECLARE_COMPLETION(startup_done);
+        struct task_struct *tsk = current;
+        struct mm_struct *mm = tsk->mm;
+        struct completion startup_done;
+        struct completion *vfork_done;
         int core_waiters;
 
+        init_completion(&mm->core_done);
+        init_completion(&startup_done);
         mm->core_startup_done = &startup_done;
 
-        zap_threads(mm);
-        core_waiters = mm->core_waiters;
+        core_waiters = zap_threads(tsk, mm, exit_code);
         up_write(&mm->mmap_sem);
 
+        if (unlikely(core_waiters < 0))
+                goto fail;
+
+        /*
+         * Make sure nobody is waiting for us to release the VM,
+         * otherwise we can deadlock when we wait on each other
+         */
+        vfork_done = tsk->vfork_done;
+        if (vfork_done) {
+                tsk->vfork_done = NULL;
+                complete(vfork_done);
+        }
+
         if (core_waiters)
                 wait_for_completion(&startup_done);
+fail:
         BUG_ON(mm->core_waiters);
+        return core_waiters;
 }
 
 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
@@ -1469,22 +1492,9 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
         }
         mm->dumpable = 0;
 
-        retval = -EAGAIN;
-        spin_lock_irq(&current->sighand->siglock);
-        if (!(current->signal->flags & SIGNAL_GROUP_EXIT)) {
-                current->signal->flags = SIGNAL_GROUP_EXIT;
-                current->signal->group_exit_code = exit_code;
-                current->signal->group_stop_count = 0;
-                retval = 0;
-        }
-        spin_unlock_irq(&current->sighand->siglock);
-        if (retval) {
-                up_write(&mm->mmap_sem);
+        retval = coredump_wait(exit_code);
+        if (retval < 0)
                 goto fail;
-        }
-
-        init_completion(&mm->core_done);
-        coredump_wait(mm);
 
         /*
          * Clear any false indication of pending signals that might