diff options
| author | Arnd Bergmann <arnd@arndb.de> | 2010-06-01 22:53:01 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-08-10 13:47:43 -0700 |
| commit | ec79d6056de58511d8e46d9ae59d3878f958dc3e (patch) | |
| tree | 8e73cf399c4cb3c31dbf3caced385cfc018a706a /include | |
| parent | 3f582b8c11014e4ce310d9839fb335164195333f (diff) | |
tty: replace BKL with a new tty_lock
As a preparation for replacing the big kernel lock
in the TTY layer, wrap all the callers in new
macros tty_lock, tty_lock_nested and tty_unlock.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/tty.h | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/include/linux/tty.h b/include/linux/tty.h index 2df60e4ff40e..6ead6b60c743 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -13,6 +13,7 @@ #include <linux/tty_driver.h> #include <linux/tty_ldisc.h> #include <linux/mutex.h> +#include <linux/smp_lock.h> #include <asm/system.h> @@ -576,5 +577,35 @@ extern int vt_ioctl(struct tty_struct *tty, struct file *file, extern long vt_compat_ioctl(struct tty_struct *tty, struct file * file, unsigned int cmd, unsigned long arg); +/* functions for preparation of BKL removal */ + +/* + * tty_lock_nested get the tty_lock while potentially holding it + * + * The Big TTY Mutex is a recursive lock, meaning you can take it + * from a thread that is already holding it. + * This is bad for a number of reasons, so tty_lock_nested should + * really be used as rarely as possible. If a code location can + * be shown to never get called with this held already, it should + * use tty_lock() instead. + */ +static inline void __lockfunc tty_lock_nested(void) __acquires(kernel_lock) +{ + lock_kernel(); +} +static inline void tty_lock(void) __acquires(kernel_lock) +{ +#ifdef CONFIG_LOCK_KERNEL + /* kernel_locked is 1 for !CONFIG_LOCK_KERNEL */ + WARN_ON(kernel_locked()); +#endif + lock_kernel(); +} +static inline void tty_unlock(void) __releases(kernel_lock) +{ + unlock_kernel(); +} +#define tty_locked() (kernel_locked()) + #endif /* __KERNEL__ */ #endif |