Merge tag 'dma-mapping-5.11' of git://git.infradead.org/users/hch/dma-mapping

[linux-2.6-microblaze.git] / kernel / exit.c

diff --git a/kernel/exit.c b/kernel/exit.c
index 733e80f..3594291 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -454,7 +454,10 @@ static void exit_mm(void)
                mmap_read_unlock(mm);
 
                self.task = current;
-               self.next = xchg(&core_state->dumper.next, &self);
+               if (self.task->flags & PF_SIGNALED)
+                       self.next = xchg(&core_state->dumper.next, &self);
+               else
+                       self.task = NULL;
                /*
                 * Implies mb(), the result of xchg() must be visible
                 * to core_state->dumper.
@@ -475,10 +478,24 @@ static void exit_mm(void)
        BUG_ON(mm != current->active_mm);
        /* more a memory barrier than a real lock */
        task_lock(current);
+       /*
+        * When a thread stops operating on an address space, the loop
+        * in membarrier_private_expedited() may not observe that
+        * tsk->mm, and the loop in membarrier_global_expedited() may
+        * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED
+        * rq->membarrier_state, so those would not issue an IPI.
+        * Membarrier requires a memory barrier after accessing
+        * user-space memory, before clearing tsk->mm or the
+        * rq->membarrier_state.
+        */
+       smp_mb__after_spinlock();
+       local_irq_disable();
        current->mm = NULL;
-       mmap_read_unlock(mm);
+       membarrier_update_current_mm(NULL);
        enter_lazy_tlb(mm, current);
+       local_irq_enable();
        task_unlock(current);
+       mmap_read_unlock(mm);
        mm_update_next_owner(mm);
        mmput(mm);
        if (test_thread_flag(TIF_MEMDIE))
@@ -1474,23 +1491,6 @@ end:
        return retval;
 }
 
-static struct pid *pidfd_get_pid(unsigned int fd)
-{
-       struct fd f;
-       struct pid *pid;
-
-       f = fdget(fd);
-       if (!f.file)
-               return ERR_PTR(-EBADF);
-
-       pid = pidfd_pid(f.file);
-       if (!IS_ERR(pid))
-               get_pid(pid);
-
-       fdput(f);
-       return pid;
-}
-
 static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
                          int options, struct rusage *ru)
 {
@@ -1498,6 +1498,7 @@ static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
        struct pid *pid = NULL;
        enum pid_type type;
        long ret;
+       unsigned int f_flags = 0;
 
        if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
                        __WNOTHREAD|__WCLONE|__WALL))
@@ -1531,9 +1532,10 @@ static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
                if (upid < 0)
                        return -EINVAL;
 
-               pid = pidfd_get_pid(upid);
+               pid = pidfd_get_pid(upid, &f_flags);
                if (IS_ERR(pid))
                        return PTR_ERR(pid);
+
                break;
        default:
                return -EINVAL;
@@ -1544,7 +1546,12 @@ static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
        wo.wo_flags     = options;
        wo.wo_info      = infop;
        wo.wo_rusage    = ru;
+       if (f_flags & O_NONBLOCK)
+               wo.wo_flags |= WNOHANG;
+
        ret = do_wait(&wo);
+       if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK))
+               ret = -EAGAIN;
 
        put_pid(pid);
        return ret;