RE: [PATCH] Fix rq->lock vs logbuf_lock unlock race

[Bu, Yitian]

> Unfortunately that's not quite possible, rq->lock is really out of bounds. At
> one point I tried 'fixing' this but there's a whole bunch of nasty that's not
> going to go away.
> 
> I've since forgotten most of the details, but aside from logbuf problems
> there's a whole host of issues with the console drivers themselves as well.
> 
> If you really want to do this, use early_printk.

Hi Peter:

The patch  0b5e1c5255e("printk: Release console_sem after logbuf_lock" )
is as below:

                        console_locked = 0;
-                       up(&console_sem);
+                       wake = 1;
                        retval = 0;
                }
        }
        printk_cpu = UINT_MAX;
        spin_unlock(&logbuf_lock);
+       if (wake)
+               up(&console_sem);
        return retval;

the patch 07354eb1a74d1("locking, printk: Annotate logbuf_lock as raw ")
is as below:

        printk_cpu = UINT_MAX;
-       spin_unlock(&logbuf_lock);
        if (wake)
                up(&console_sem);
+       raw_spin_unlock(&logbuf_lock);
        return retval;
 }

Note that the purpose of patch 07354eb1a74d1 is to use raw_spin_unlock
instead of spin_unlock, it is not supposed to change any lock sequences.

What I do is to revert this change to 0b5e1c5255e, and it is nothing to do with
how people use printk. It is just to recover a merge mistake.