diff options
author | John Ogness <john.ogness@linutronix.de> | 2022-11-16 17:27:33 +0106 |
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committer | Petr Mladek <pmladek@suse.com> | 2022-12-02 11:25:01 +0100 |
commit | 1fd4224a6b641f1949e27bf350b5b1c1e47e2ccc (patch) | |
tree | b448d2573cb65c80b2541b6636753c6a8595aa94 /include | |
parent | 8cb15f7f492f85d695a6f4d12044c47230f69d96 (diff) | |
download | linux-1fd4224a6b641f1949e27bf350b5b1c1e47e2ccc.tar.bz2 |
console: introduce console_is_registered()
Currently it is not possible for drivers to detect if they have
already successfully registered their console. Several drivers
have multiple paths that lead to console registration. To avoid
attempting a 2nd registration (which leads to a WARN), drivers
are implementing their own solution.
Introduce console_is_registered() so drivers can easily identify
if their console is currently registered. A _locked() variant
is also provided if the caller is already holding the
console_list_lock.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-22-john.ogness@linutronix.de
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/console.h | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/include/linux/console.h b/include/linux/console.h index c1ca461d088a..f716e1dd9eaf 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -228,6 +228,34 @@ static inline void console_srcu_write_flags(struct console *con, short flags) WRITE_ONCE(con->flags, flags); } +/* Variant of console_is_registered() when the console_list_lock is held. */ +static inline bool console_is_registered_locked(const struct console *con) +{ + lockdep_assert_console_list_lock_held(); + return !hlist_unhashed(&con->node); +} + +/* + * console_is_registered - Check if the console is registered + * @con: struct console pointer of console to check + * + * Context: Process context. May sleep while acquiring console list lock. + * Return: true if the console is in the console list, otherwise false. + * + * If false is returned for a console that was previously registered, it + * can be assumed that the console's unregistration is fully completed, + * including the exit() callback after console list removal. + */ +static inline bool console_is_registered(const struct console *con) +{ + bool ret; + + console_list_lock(); + ret = console_is_registered_locked(con); + console_list_unlock(); + return ret; +} + /** * for_each_console_srcu() - Iterator over registered consoles * @con: struct console pointer used as loop cursor |