diff options
Diffstat (limited to 'include/linux/console.h')
| -rw-r--r-- | include/linux/console.h | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/include/linux/console.h b/include/linux/console.h index d17f1f525bec..5f17321ed962 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -186,6 +186,8 @@ static inline void con_debug_leave(void) { } * printing callbacks must not be called. * @CON_NBCON: Console can operate outside of the legacy style console_lock * constraints. + * @CON_NBCON_ATOMIC_UNSAFE: The write_atomic() callback is not safe and is + * therefore only used by nbcon_atomic_flush_unsafe(). */ enum cons_flags { CON_PRINTBUFFER = BIT(0), @@ -197,6 +199,7 @@ enum cons_flags { CON_EXTENDED = BIT(6), CON_SUSPENDED = BIT(7), CON_NBCON = BIT(8), + CON_NBCON_ATOMIC_UNSAFE = BIT(9), }; /** @@ -608,6 +611,7 @@ extern void nbcon_write_context_set_buf(struct nbcon_write_context *wctxt, extern bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt); extern bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt); extern void nbcon_reacquire_nobuf(struct nbcon_write_context *wctxt); +extern bool nbcon_allow_unsafe_takeover(void); extern bool nbcon_kdb_try_acquire(struct console *con, struct nbcon_write_context *wctxt); extern void nbcon_kdb_release(struct nbcon_write_context *wctxt); @@ -627,9 +631,18 @@ static inline bool console_is_usable(struct console *con, short flags, bool use_ return false; if (flags & CON_NBCON) { - /* The write_atomic() callback is optional. */ - if (use_atomic && !con->write_atomic) - return false; + if (use_atomic) { + /* The write_atomic() callback is optional. */ + if (!con->write_atomic) + return false; + + /* + * An unsafe write_atomic() callback is only usable + * when unsafe takeovers are allowed. + */ + if ((flags & CON_NBCON_ATOMIC_UNSAFE) && !nbcon_allow_unsafe_takeover()) + return false; + } /* * For the !use_atomic case, @printk_kthreads_running is not |