tree 954f091db10fc2036937e07c9bbacf8e9180a575
parent 20f634615cf93f80d77529bf97109891f481566b
author Barret Rhoden <brho@cs.berkeley.edu> 1532026449 -0400
committer Barret Rhoden <brho@cs.berkeley.edu> 1532026449 -0400

Support atomic printks

printk() was atomic at the granularity of a line - most of the time.  It
wasn't for kernel faults, which leads to inscrutable bug reports.  At the
time, I avoided the lock to avoid deadlocking.  Instead, we can use a
recursive lock, which I'm not normally a fan of.

Additionally, other callers can use print_lock() to atomically print
multiple lines.  The classic example is panic() and warn().  panic() has a
few issues of its own, so we have print_unlock_force().

Signed-off-by: Barret Rhoden <brho@cs.berkeley.edu>