diff options
Diffstat (limited to 'drivers/char')
-rw-r--r-- | drivers/char/Makefile | 1 | ||||
-rw-r--r-- | drivers/char/tty_mutex.c | 47 |
2 files changed, 48 insertions, 0 deletions
diff --git a/drivers/char/Makefile b/drivers/char/Makefile index 273cee1..dc96416 100644 --- a/drivers/char/Makefile +++ b/drivers/char/Makefile @@ -9,6 +9,7 @@ FONTMAPFILE = cp437.uni obj-y += mem.o random.o tty_io.o n_tty.o tty_ioctl.o tty_ldisc.o tty_buffer.o tty_port.o +obj-y += tty_mutex.o obj-$(CONFIG_LEGACY_PTYS) += pty.o obj-$(CONFIG_UNIX98_PTYS) += pty.o obj-y += misc.o diff --git a/drivers/char/tty_mutex.c b/drivers/char/tty_mutex.c new file mode 100644 index 0000000..1336975 --- /dev/null +++ b/drivers/char/tty_mutex.c @@ -0,0 +1,47 @@ +/* + * drivers/char/tty_lock.c + */ +#include <linux/tty.h> +#include <linux/module.h> +#include <linux/kallsyms.h> +#include <linux/semaphore.h> +#include <linux/sched.h> + +/* + * The 'big tty mutex' + * + * This mutex is taken and released by tty_lock() and tty_unlock(), + * replacing the older big kernel lock. + * It can no longer be taken recursively, and does not get + * released implicitly while sleeping. + * + * Don't use in new code. + */ +static DEFINE_MUTEX(big_tty_mutex); +struct task_struct *__big_tty_mutex_owner; +EXPORT_SYMBOL_GPL(__big_tty_mutex_owner); + +/* + * Getting the big tty mutex. + */ +void __lockfunc tty_lock(void) +{ + struct task_struct *task = current; + + WARN_ON(__big_tty_mutex_owner == task); + + mutex_lock(&big_tty_mutex); + __big_tty_mutex_owner = task; +} +EXPORT_SYMBOL(tty_lock); + +void __lockfunc tty_unlock(void) +{ + struct task_struct *task = current; + + WARN_ON(__big_tty_mutex_owner != task); + __big_tty_mutex_owner = NULL; + + mutex_unlock(&big_tty_mutex); +} +EXPORT_SYMBOL(tty_unlock); |