diff options
| author | Chunwei Chen <[email protected]> | 2016-04-12 12:05:14 -0700 |
|---|---|---|
| committer | Brian Behlendorf <[email protected]> | 2016-04-25 17:04:07 -0700 |
| commit | cdd39dd2457ac57622339669db0536a580374bd3 (patch) | |
| tree | 71a77ae2758f91df5385fe4e6181eb755e619422 | |
| parent | 224817e2a81912b46453a96b9eec4804856c801b (diff) | |
Use kernel provided mutex owner
To reduce mutex footprint, we detect the existence of owner in kernel mutex,
and rely on it if it exists.
Note that before Linux 3.0, mutex owner is of type thread_info. Also note
that, in Linux 3.18, the condition for owner is changed from
CONFIG_DEBUG_MUTEXES || CONFIG_SMP to
CONFIG_DEBUG_MUTEXES || CONFIG_MUTEX_SPIN_ON_OWNER
Signed-off-by: Chunwei Chen <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #540
| -rw-r--r-- | config/spl-build.m4 | 29 | ||||
| -rw-r--r-- | include/sys/mutex.h | 15 |
2 files changed, 44 insertions, 0 deletions
diff --git a/config/spl-build.m4 b/config/spl-build.m4 index b9c04a95e..55453c822 100644 --- a/config/spl-build.m4 +++ b/config/spl-build.m4 @@ -44,6 +44,7 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [ SPL_AC_USLEEP_RANGE SPL_AC_KMEM_CACHE_ALLOCFLAGS SPL_AC_WAIT_ON_BIT + SPL_AC_MUTEX_OWNER ]) AC_DEFUN([SPL_AC_MODULE_SYMVERS], [ @@ -1447,3 +1448,31 @@ AC_DEFUN([SPL_AC_WAIT_ON_BIT], [ AC_MSG_RESULT(no) ]) ]) + +dnl # +dnl # Check whether mutex has owner with task_struct type. +dnl # +dnl # Note that before Linux 3.0, mutex owner is of type thread_info. +dnl # +dnl # Note that in Linux 3.18, the condition for owner is changed from +dnl # defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_SMP) to +dnl # defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_MUTEX_SPIN_ON_OWNER) +dnl # +AC_DEFUN([SPL_AC_MUTEX_OWNER], [ + AC_MSG_CHECKING([whether mutex has owner]) + tmp_flags="$EXTRA_KCFLAGS" + EXTRA_KCFLAGS="-Werror" + SPL_LINUX_TRY_COMPILE([ + #include <linux/mutex.h> + ],[ + DEFINE_MUTEX(m); + struct task_struct *t __attribute__ ((unused)); + t = m.owner; + ],[ + AC_MSG_RESULT(yes) + AC_DEFINE(HAVE_MUTEX_OWNER, 1, [yes]) + ],[ + AC_MSG_RESULT(no) + ]) + EXTRA_KCFLAGS="$tmp_flags" +]) diff --git a/include/sys/mutex.h b/include/sys/mutex.h index fba35f3f9..319235223 100644 --- a/include/sys/mutex.h +++ b/include/sys/mutex.h @@ -40,7 +40,10 @@ typedef enum { typedef struct { struct mutex m_mutex; spinlock_t m_lock; /* used for serializing mutex_exit */ +#ifndef HAVE_MUTEX_OWNER + /* only when kernel doesn't have owner */ kthread_t *m_owner; +#endif #ifdef CONFIG_LOCKDEP kmutex_type_t m_type; #endif /* CONFIG_LOCKDEP */ @@ -51,16 +54,28 @@ typedef struct { static inline void spl_mutex_set_owner(kmutex_t *mp) { + /* + * kernel will handle its owner, so we don't need to do anything if it + * is defined. + */ +#ifndef HAVE_MUTEX_OWNER mp->m_owner = current; +#endif } static inline void spl_mutex_clear_owner(kmutex_t *mp) { +#ifndef HAVE_MUTEX_OWNER mp->m_owner = NULL; +#endif } +#ifdef HAVE_MUTEX_OWNER +#define mutex_owner(mp) (ACCESS_ONCE(MUTEX(mp)->owner)) +#else #define mutex_owner(mp) (ACCESS_ONCE((mp)->m_owner)) +#endif #define mutex_owned(mp) (mutex_owner(mp) == current) #define MUTEX_HELD(mp) mutex_owned(mp) #define MUTEX_NOT_HELD(mp) (!MUTEX_HELD(mp)) |