Archive-Team
/
zfs
2
0
Fork 0
Code Issues Pull Requests Packages Projects Releases 103 Wiki Activity

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 <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #540
This commit is contained in:
Chunwei Chen 2016-04-12 12:05:14 -07:00 committed by Brian Behlendorf
parent 224817e2a8
commit cdd39dd245
2 changed files with 44 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
config/spl-build.m4
View File

@ -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"
])

15
include/sys/mutex.h
View File

@ -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))