zfs/include/os/linux/spl/sys/mutex.h

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/*
* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
* Copyright (C) 2007 The Regents of the University of California.
* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
* UCRL-CODE-235197
*
* This file is part of the SPL, Solaris Porting Layer.
*
* The SPL is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* The SPL is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with the SPL. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _SPL_MUTEX_H
#define _SPL_MUTEX_H
#include <sys/types.h>
#include <linux/sched.h>
Reimplement mutexs for Linux lock profiling/analysis For a generic explanation of why mutexs needed to be reimplemented to work with the kernel lock profiling see commits: e811949a57044d60d12953c5c3b808a79a7d36ef and d28db80fd0fd4fd63aec09037c44408e51a222d6 The specific changes made to the mutex implemetation are as follows. The Linux mutex structure is now directly embedded in the kmutex_t. This allows a kmutex_t to be directly case to a mutex struct and passed directly to the Linux primative. Just like with the rwlocks it is critical that these functions be implemented as '#defines to ensure the location information is preserved. The preprocessor can then do a direct replacement of the Solaris primative with the linux primative. Just as with the rwlocks we need to track the lock owner. Here things get a little more interesting because depending on your kernel version, and how you've built your kernel Linux may already do this for you. If your running a 2.6.29 or newer kernel on a SMP system the lock owner will be tracked. This was added to Linux to support adaptive mutexs, more on that shortly. Alternately, your kernel might track the lock owner if you've set CONFIG_DEBUG_MUTEXES in the kernel build. If neither of the above things is true for your kernel the kmutex_t type will include and track the lock owner to ensure correct behavior. This is all handled by a new autoconf check called SPL_AC_MUTEX_OWNER. Concerning adaptive mutexs these are a very recent development and they did not make it in to either the latest FC11 of SLES11 kernels. Ideally, I'd love to see this kernel change appear in one of these distros because it does help performance. From Linux kernel commit: 0d66bf6d3514b35eb6897629059443132992dbd7 "Testing with Ingo's test-mutex application... gave a 345% boost for VFS scalability on my testbox" However, if you don't want to backport this change yourself you can still simply export the task_curr() symbol. The kmutex_t implementation will use this symbol when it's available to provide it's own adaptive mutexs. Finally, DEBUG_MUTEX support was removed including the proc handlers. This was done because now that we are cleanly integrated with the kernel profiling all this information and much much more is available in debug kernel builds. This code was now redundant. Update mutexs validated on: - SLES10 (ppc64) - SLES11 (x86_64) - CHAOS4.2 (x86_64) - RHEL5.3 (x86_64) - RHEL6 (x86_64) - FC11 (x86_64)
2009-09-25 21:47:01 +00:00
#include <linux/mutex.h>
#include <linux/lockdep.h>
Update build system and packaging Minimal changes required to integrate the SPL sources in to the ZFS repository build infrastructure and packaging. Build system and packaging: * Renamed SPL_* autoconf m4 macros to ZFS_*. * Removed redundant SPL_* autoconf m4 macros. * Updated the RPM spec files to remove SPL package dependency. * The zfs package obsoletes the spl package, and the zfs-kmod package obsoletes the spl-kmod package. * The zfs-kmod-devel* packages were updated to add compatibility symlinks under /usr/src/spl-x.y.z until all dependent packages can be updated. They will be removed in a future release. * Updated copy-builtin script for in-kernel builds. * Updated DKMS package to include the spl.ko. * Updated stale AUTHORS file to include all contributors. * Updated stale COPYRIGHT and included the SPL as an exception. * Renamed README.markdown to README.md * Renamed OPENSOLARIS.LICENSE to LICENSE. * Renamed DISCLAIMER to NOTICE. Required code changes: * Removed redundant HAVE_SPL macro. * Removed _BOOT from nvpairs since it doesn't apply for Linux. * Initial header cleanup (removal of empty headers, refactoring). * Remove SPL repository clone/build from zimport.sh. * Use of DEFINE_RATELIMIT_STATE and DEFINE_SPINLOCK removed due to build issues when forcing C99 compilation. * Replaced legacy ACCESS_ONCE with READ_ONCE. * Include needed headers for `current` and `EXPORT_SYMBOL`. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: Olaf Faaland <faaland1@llnl.gov> Reviewed-by: Matthew Ahrens <mahrens@delphix.com> Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> TEST_ZIMPORT_SKIP="yes" Closes #7556
2018-02-16 01:53:18 +00:00
#include <linux/compiler_compat.h>
Reimplement mutexs for Linux lock profiling/analysis For a generic explanation of why mutexs needed to be reimplemented to work with the kernel lock profiling see commits: e811949a57044d60d12953c5c3b808a79a7d36ef and d28db80fd0fd4fd63aec09037c44408e51a222d6 The specific changes made to the mutex implemetation are as follows. The Linux mutex structure is now directly embedded in the kmutex_t. This allows a kmutex_t to be directly case to a mutex struct and passed directly to the Linux primative. Just like with the rwlocks it is critical that these functions be implemented as '#defines to ensure the location information is preserved. The preprocessor can then do a direct replacement of the Solaris primative with the linux primative. Just as with the rwlocks we need to track the lock owner. Here things get a little more interesting because depending on your kernel version, and how you've built your kernel Linux may already do this for you. If your running a 2.6.29 or newer kernel on a SMP system the lock owner will be tracked. This was added to Linux to support adaptive mutexs, more on that shortly. Alternately, your kernel might track the lock owner if you've set CONFIG_DEBUG_MUTEXES in the kernel build. If neither of the above things is true for your kernel the kmutex_t type will include and track the lock owner to ensure correct behavior. This is all handled by a new autoconf check called SPL_AC_MUTEX_OWNER. Concerning adaptive mutexs these are a very recent development and they did not make it in to either the latest FC11 of SLES11 kernels. Ideally, I'd love to see this kernel change appear in one of these distros because it does help performance. From Linux kernel commit: 0d66bf6d3514b35eb6897629059443132992dbd7 "Testing with Ingo's test-mutex application... gave a 345% boost for VFS scalability on my testbox" However, if you don't want to backport this change yourself you can still simply export the task_curr() symbol. The kmutex_t implementation will use this symbol when it's available to provide it's own adaptive mutexs. Finally, DEBUG_MUTEX support was removed including the proc handlers. This was done because now that we are cleanly integrated with the kernel profiling all this information and much much more is available in debug kernel builds. This code was now redundant. Update mutexs validated on: - SLES10 (ppc64) - SLES11 (x86_64) - CHAOS4.2 (x86_64) - RHEL5.3 (x86_64) - RHEL6 (x86_64) - FC11 (x86_64)
2009-09-25 21:47:01 +00:00
typedef enum {
MUTEX_DEFAULT = 0,
MUTEX_SPIN = 1,
MUTEX_ADAPTIVE = 2,
MUTEX_NOLOCKDEP = 3
Reimplement mutexs for Linux lock profiling/analysis For a generic explanation of why mutexs needed to be reimplemented to work with the kernel lock profiling see commits: e811949a57044d60d12953c5c3b808a79a7d36ef and d28db80fd0fd4fd63aec09037c44408e51a222d6 The specific changes made to the mutex implemetation are as follows. The Linux mutex structure is now directly embedded in the kmutex_t. This allows a kmutex_t to be directly case to a mutex struct and passed directly to the Linux primative. Just like with the rwlocks it is critical that these functions be implemented as '#defines to ensure the location information is preserved. The preprocessor can then do a direct replacement of the Solaris primative with the linux primative. Just as with the rwlocks we need to track the lock owner. Here things get a little more interesting because depending on your kernel version, and how you've built your kernel Linux may already do this for you. If your running a 2.6.29 or newer kernel on a SMP system the lock owner will be tracked. This was added to Linux to support adaptive mutexs, more on that shortly. Alternately, your kernel might track the lock owner if you've set CONFIG_DEBUG_MUTEXES in the kernel build. If neither of the above things is true for your kernel the kmutex_t type will include and track the lock owner to ensure correct behavior. This is all handled by a new autoconf check called SPL_AC_MUTEX_OWNER. Concerning adaptive mutexs these are a very recent development and they did not make it in to either the latest FC11 of SLES11 kernels. Ideally, I'd love to see this kernel change appear in one of these distros because it does help performance. From Linux kernel commit: 0d66bf6d3514b35eb6897629059443132992dbd7 "Testing with Ingo's test-mutex application... gave a 345% boost for VFS scalability on my testbox" However, if you don't want to backport this change yourself you can still simply export the task_curr() symbol. The kmutex_t implementation will use this symbol when it's available to provide it's own adaptive mutexs. Finally, DEBUG_MUTEX support was removed including the proc handlers. This was done because now that we are cleanly integrated with the kernel profiling all this information and much much more is available in debug kernel builds. This code was now redundant. Update mutexs validated on: - SLES10 (ppc64) - SLES11 (x86_64) - CHAOS4.2 (x86_64) - RHEL5.3 (x86_64) - RHEL6 (x86_64) - FC11 (x86_64)
2009-09-25 21:47:01 +00:00
} kmutex_type_t;
typedef struct {
struct mutex m_mutex;
spinlock_t m_lock; /* used for serializing mutex_exit */
kthread_t *m_owner;
#ifdef CONFIG_LOCKDEP
kmutex_type_t m_type;
#endif /* CONFIG_LOCKDEP */
} kmutex_t;
#define MUTEX(mp) (&((mp)->m_mutex))
static inline void
spl_mutex_set_owner(kmutex_t *mp)
{
mp->m_owner = current;
}
static inline void
spl_mutex_clear_owner(kmutex_t *mp)
{
mp->m_owner = NULL;
}
Update build system and packaging Minimal changes required to integrate the SPL sources in to the ZFS repository build infrastructure and packaging. Build system and packaging: * Renamed SPL_* autoconf m4 macros to ZFS_*. * Removed redundant SPL_* autoconf m4 macros. * Updated the RPM spec files to remove SPL package dependency. * The zfs package obsoletes the spl package, and the zfs-kmod package obsoletes the spl-kmod package. * The zfs-kmod-devel* packages were updated to add compatibility symlinks under /usr/src/spl-x.y.z until all dependent packages can be updated. They will be removed in a future release. * Updated copy-builtin script for in-kernel builds. * Updated DKMS package to include the spl.ko. * Updated stale AUTHORS file to include all contributors. * Updated stale COPYRIGHT and included the SPL as an exception. * Renamed README.markdown to README.md * Renamed OPENSOLARIS.LICENSE to LICENSE. * Renamed DISCLAIMER to NOTICE. Required code changes: * Removed redundant HAVE_SPL macro. * Removed _BOOT from nvpairs since it doesn't apply for Linux. * Initial header cleanup (removal of empty headers, refactoring). * Remove SPL repository clone/build from zimport.sh. * Use of DEFINE_RATELIMIT_STATE and DEFINE_SPINLOCK removed due to build issues when forcing C99 compilation. * Replaced legacy ACCESS_ONCE with READ_ONCE. * Include needed headers for `current` and `EXPORT_SYMBOL`. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: Olaf Faaland <faaland1@llnl.gov> Reviewed-by: Matthew Ahrens <mahrens@delphix.com> Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> TEST_ZIMPORT_SKIP="yes" Closes #7556
2018-02-16 01:53:18 +00:00
#define mutex_owner(mp) (READ_ONCE((mp)->m_owner))
#define mutex_owned(mp) (mutex_owner(mp) == current)
#define MUTEX_HELD(mp) mutex_owned(mp)
#define MUTEX_NOT_HELD(mp) (!MUTEX_HELD(mp))
#ifdef CONFIG_LOCKDEP
static inline void
spl_mutex_set_type(kmutex_t *mp, kmutex_type_t type)
{
mp->m_type = type;
}
static inline void
spl_mutex_lockdep_off_maybe(kmutex_t *mp) \
{ \
if (mp && mp->m_type == MUTEX_NOLOCKDEP) \
lockdep_off(); \
}
static inline void
spl_mutex_lockdep_on_maybe(kmutex_t *mp) \
{ \
if (mp && mp->m_type == MUTEX_NOLOCKDEP) \
lockdep_on(); \
}
#else /* CONFIG_LOCKDEP */
#define spl_mutex_set_type(mp, type)
#define spl_mutex_lockdep_off_maybe(mp)
#define spl_mutex_lockdep_on_maybe(mp)
#endif /* CONFIG_LOCKDEP */
Reimplement mutexs for Linux lock profiling/analysis For a generic explanation of why mutexs needed to be reimplemented to work with the kernel lock profiling see commits: e811949a57044d60d12953c5c3b808a79a7d36ef and d28db80fd0fd4fd63aec09037c44408e51a222d6 The specific changes made to the mutex implemetation are as follows. The Linux mutex structure is now directly embedded in the kmutex_t. This allows a kmutex_t to be directly case to a mutex struct and passed directly to the Linux primative. Just like with the rwlocks it is critical that these functions be implemented as '#defines to ensure the location information is preserved. The preprocessor can then do a direct replacement of the Solaris primative with the linux primative. Just as with the rwlocks we need to track the lock owner. Here things get a little more interesting because depending on your kernel version, and how you've built your kernel Linux may already do this for you. If your running a 2.6.29 or newer kernel on a SMP system the lock owner will be tracked. This was added to Linux to support adaptive mutexs, more on that shortly. Alternately, your kernel might track the lock owner if you've set CONFIG_DEBUG_MUTEXES in the kernel build. If neither of the above things is true for your kernel the kmutex_t type will include and track the lock owner to ensure correct behavior. This is all handled by a new autoconf check called SPL_AC_MUTEX_OWNER. Concerning adaptive mutexs these are a very recent development and they did not make it in to either the latest FC11 of SLES11 kernels. Ideally, I'd love to see this kernel change appear in one of these distros because it does help performance. From Linux kernel commit: 0d66bf6d3514b35eb6897629059443132992dbd7 "Testing with Ingo's test-mutex application... gave a 345% boost for VFS scalability on my testbox" However, if you don't want to backport this change yourself you can still simply export the task_curr() symbol. The kmutex_t implementation will use this symbol when it's available to provide it's own adaptive mutexs. Finally, DEBUG_MUTEX support was removed including the proc handlers. This was done because now that we are cleanly integrated with the kernel profiling all this information and much much more is available in debug kernel builds. This code was now redundant. Update mutexs validated on: - SLES10 (ppc64) - SLES11 (x86_64) - CHAOS4.2 (x86_64) - RHEL5.3 (x86_64) - RHEL6 (x86_64) - FC11 (x86_64)
2009-09-25 21:47:01 +00:00
/*
* The following functions must be a #define and not static inline.
Reimplement mutexs for Linux lock profiling/analysis For a generic explanation of why mutexs needed to be reimplemented to work with the kernel lock profiling see commits: e811949a57044d60d12953c5c3b808a79a7d36ef and d28db80fd0fd4fd63aec09037c44408e51a222d6 The specific changes made to the mutex implemetation are as follows. The Linux mutex structure is now directly embedded in the kmutex_t. This allows a kmutex_t to be directly case to a mutex struct and passed directly to the Linux primative. Just like with the rwlocks it is critical that these functions be implemented as '#defines to ensure the location information is preserved. The preprocessor can then do a direct replacement of the Solaris primative with the linux primative. Just as with the rwlocks we need to track the lock owner. Here things get a little more interesting because depending on your kernel version, and how you've built your kernel Linux may already do this for you. If your running a 2.6.29 or newer kernel on a SMP system the lock owner will be tracked. This was added to Linux to support adaptive mutexs, more on that shortly. Alternately, your kernel might track the lock owner if you've set CONFIG_DEBUG_MUTEXES in the kernel build. If neither of the above things is true for your kernel the kmutex_t type will include and track the lock owner to ensure correct behavior. This is all handled by a new autoconf check called SPL_AC_MUTEX_OWNER. Concerning adaptive mutexs these are a very recent development and they did not make it in to either the latest FC11 of SLES11 kernels. Ideally, I'd love to see this kernel change appear in one of these distros because it does help performance. From Linux kernel commit: 0d66bf6d3514b35eb6897629059443132992dbd7 "Testing with Ingo's test-mutex application... gave a 345% boost for VFS scalability on my testbox" However, if you don't want to backport this change yourself you can still simply export the task_curr() symbol. The kmutex_t implementation will use this symbol when it's available to provide it's own adaptive mutexs. Finally, DEBUG_MUTEX support was removed including the proc handlers. This was done because now that we are cleanly integrated with the kernel profiling all this information and much much more is available in debug kernel builds. This code was now redundant. Update mutexs validated on: - SLES10 (ppc64) - SLES11 (x86_64) - CHAOS4.2 (x86_64) - RHEL5.3 (x86_64) - RHEL6 (x86_64) - FC11 (x86_64)
2009-09-25 21:47:01 +00:00
* This ensures that the native linux mutex functions (lock/unlock)
* will be correctly located in the users code which is important
* for the built in kernel lock analysis tools
*/
#undef mutex_init
#define mutex_init(mp, name, type, ibc) \
{ \
static struct lock_class_key __key; \
ASSERT(type == MUTEX_DEFAULT || type == MUTEX_NOLOCKDEP); \
\
__mutex_init(MUTEX(mp), (name) ? (#name) : (#mp), &__key); \
spin_lock_init(&(mp)->m_lock); \
spl_mutex_clear_owner(mp); \
spl_mutex_set_type(mp, type); \
}
Reimplement mutexs for Linux lock profiling/analysis For a generic explanation of why mutexs needed to be reimplemented to work with the kernel lock profiling see commits: e811949a57044d60d12953c5c3b808a79a7d36ef and d28db80fd0fd4fd63aec09037c44408e51a222d6 The specific changes made to the mutex implemetation are as follows. The Linux mutex structure is now directly embedded in the kmutex_t. This allows a kmutex_t to be directly case to a mutex struct and passed directly to the Linux primative. Just like with the rwlocks it is critical that these functions be implemented as '#defines to ensure the location information is preserved. The preprocessor can then do a direct replacement of the Solaris primative with the linux primative. Just as with the rwlocks we need to track the lock owner. Here things get a little more interesting because depending on your kernel version, and how you've built your kernel Linux may already do this for you. If your running a 2.6.29 or newer kernel on a SMP system the lock owner will be tracked. This was added to Linux to support adaptive mutexs, more on that shortly. Alternately, your kernel might track the lock owner if you've set CONFIG_DEBUG_MUTEXES in the kernel build. If neither of the above things is true for your kernel the kmutex_t type will include and track the lock owner to ensure correct behavior. This is all handled by a new autoconf check called SPL_AC_MUTEX_OWNER. Concerning adaptive mutexs these are a very recent development and they did not make it in to either the latest FC11 of SLES11 kernels. Ideally, I'd love to see this kernel change appear in one of these distros because it does help performance. From Linux kernel commit: 0d66bf6d3514b35eb6897629059443132992dbd7 "Testing with Ingo's test-mutex application... gave a 345% boost for VFS scalability on my testbox" However, if you don't want to backport this change yourself you can still simply export the task_curr() symbol. The kmutex_t implementation will use this symbol when it's available to provide it's own adaptive mutexs. Finally, DEBUG_MUTEX support was removed including the proc handlers. This was done because now that we are cleanly integrated with the kernel profiling all this information and much much more is available in debug kernel builds. This code was now redundant. Update mutexs validated on: - SLES10 (ppc64) - SLES11 (x86_64) - CHAOS4.2 (x86_64) - RHEL5.3 (x86_64) - RHEL6 (x86_64) - FC11 (x86_64)
2009-09-25 21:47:01 +00:00
#undef mutex_destroy
#define mutex_destroy(mp) \
{ \
VERIFY3P(mutex_owner(mp), ==, NULL); \
}
#define mutex_tryenter(mp) \
/* CSTYLED */ \
({ \
int _rc_; \
\
spl_mutex_lockdep_off_maybe(mp); \
if ((_rc_ = mutex_trylock(MUTEX(mp))) == 1) \
spl_mutex_set_owner(mp); \
spl_mutex_lockdep_on_maybe(mp); \
\
_rc_; \
})
Fix lockdep recursive locking false positive in dbuf_destroy lockdep reports a possible recursive lock in dbuf_destroy. It is true that dbuf_destroy is acquiring the dn_dbufs_mtx on one dnode while holding it on another dnode. However, it is impossible for these to be the same dnode because, among other things,dbuf_destroy checks MUTEX_HELD before acquiring the mutex. This fix defines a class NESTED_SINGLE == 1 and changes that lock to call mutex_enter_nested with a subclass of NESTED_SINGLE. In order to make the userspace code compile, include/sys/zfs_context.h now defines mutex_enter_nested and NESTED_SINGLE. This is the lockdep report: [ 122.950921] ============================================ [ 122.950921] WARNING: possible recursive locking detected [ 122.950921] 4.19.29-4.19.0-debug-d69edad5368c1166 #1 Tainted: G O [ 122.950921] -------------------------------------------- [ 122.950921] dbu_evict/1457 is trying to acquire lock: [ 122.950921] 0000000083e9cbcf (&dn->dn_dbufs_mtx){+.+.}, at: dbuf_destroy+0x3c0/0xdb0 [zfs] [ 122.950921] but task is already holding lock: [ 122.950921] 0000000055523987 (&dn->dn_dbufs_mtx){+.+.}, at: dnode_evict_dbufs+0x90/0x740 [zfs] [ 122.950921] other info that might help us debug this: [ 122.950921] Possible unsafe locking scenario: [ 122.950921] CPU0 [ 122.950921] ---- [ 122.950921] lock(&dn->dn_dbufs_mtx); [ 122.950921] lock(&dn->dn_dbufs_mtx); [ 122.950921] *** DEADLOCK *** [ 122.950921] May be due to missing lock nesting notation [ 122.950921] 1 lock held by dbu_evict/1457: [ 122.950921] #0: 0000000055523987 (&dn->dn_dbufs_mtx){+.+.}, at: dnode_evict_dbufs+0x90/0x740 [zfs] [ 122.950921] stack backtrace: [ 122.950921] CPU: 0 PID: 1457 Comm: dbu_evict Tainted: G O 4.19.29-4.19.0-debug-d69edad5368c1166 #1 [ 122.950921] Hardware name: Supermicro H8SSL-I2/H8SSL-I2, BIOS 080011 03/13/2009 [ 122.950921] Call Trace: [ 122.950921] dump_stack+0x91/0xeb [ 122.950921] __lock_acquire+0x2ca7/0x4f10 [ 122.950921] lock_acquire+0x153/0x330 [ 122.950921] dbuf_destroy+0x3c0/0xdb0 [zfs] [ 122.950921] dbuf_evict_one+0x1cc/0x3d0 [zfs] [ 122.950921] dbuf_rele_and_unlock+0xb84/0xd60 [zfs] [ 122.950921] dnode_evict_dbufs+0x3a6/0x740 [zfs] [ 122.950921] dmu_objset_evict+0x7a/0x500 [zfs] [ 122.950921] dsl_dataset_evict_async+0x70/0x480 [zfs] [ 122.950921] taskq_thread+0x979/0x1480 [spl] [ 122.950921] kthread+0x2e7/0x3e0 [ 122.950921] ret_from_fork+0x27/0x50 Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Jeff Dike <jdike@akamai.com> Closes #8984
2019-07-17 16:18:24 +00:00
#define NESTED_SINGLE 1
#ifdef CONFIG_DEBUG_LOCK_ALLOC
#define mutex_enter_nested(mp, subclass) \
{ \
ASSERT3P(mutex_owner(mp), !=, current); \
spl_mutex_lockdep_off_maybe(mp); \
mutex_lock_nested(MUTEX(mp), (subclass)); \
spl_mutex_lockdep_on_maybe(mp); \
spl_mutex_set_owner(mp); \
}
#else /* CONFIG_DEBUG_LOCK_ALLOC */
#define mutex_enter_nested(mp, subclass) \
{ \
ASSERT3P(mutex_owner(mp), !=, current); \
spl_mutex_lockdep_off_maybe(mp); \
mutex_lock(MUTEX(mp)); \
spl_mutex_lockdep_on_maybe(mp); \
spl_mutex_set_owner(mp); \
}
#endif /* CONFIG_DEBUG_LOCK_ALLOC */
#define mutex_enter(mp) mutex_enter_nested((mp), 0)
Reimplement mutexs for Linux lock profiling/analysis For a generic explanation of why mutexs needed to be reimplemented to work with the kernel lock profiling see commits: e811949a57044d60d12953c5c3b808a79a7d36ef and d28db80fd0fd4fd63aec09037c44408e51a222d6 The specific changes made to the mutex implemetation are as follows. The Linux mutex structure is now directly embedded in the kmutex_t. This allows a kmutex_t to be directly case to a mutex struct and passed directly to the Linux primative. Just like with the rwlocks it is critical that these functions be implemented as '#defines to ensure the location information is preserved. The preprocessor can then do a direct replacement of the Solaris primative with the linux primative. Just as with the rwlocks we need to track the lock owner. Here things get a little more interesting because depending on your kernel version, and how you've built your kernel Linux may already do this for you. If your running a 2.6.29 or newer kernel on a SMP system the lock owner will be tracked. This was added to Linux to support adaptive mutexs, more on that shortly. Alternately, your kernel might track the lock owner if you've set CONFIG_DEBUG_MUTEXES in the kernel build. If neither of the above things is true for your kernel the kmutex_t type will include and track the lock owner to ensure correct behavior. This is all handled by a new autoconf check called SPL_AC_MUTEX_OWNER. Concerning adaptive mutexs these are a very recent development and they did not make it in to either the latest FC11 of SLES11 kernels. Ideally, I'd love to see this kernel change appear in one of these distros because it does help performance. From Linux kernel commit: 0d66bf6d3514b35eb6897629059443132992dbd7 "Testing with Ingo's test-mutex application... gave a 345% boost for VFS scalability on my testbox" However, if you don't want to backport this change yourself you can still simply export the task_curr() symbol. The kmutex_t implementation will use this symbol when it's available to provide it's own adaptive mutexs. Finally, DEBUG_MUTEX support was removed including the proc handlers. This was done because now that we are cleanly integrated with the kernel profiling all this information and much much more is available in debug kernel builds. This code was now redundant. Update mutexs validated on: - SLES10 (ppc64) - SLES11 (x86_64) - CHAOS4.2 (x86_64) - RHEL5.3 (x86_64) - RHEL6 (x86_64) - FC11 (x86_64)
2009-09-25 21:47:01 +00:00
/*
* The reason for the spinlock:
*
* The Linux mutex is designed with a fast-path/slow-path design such that it
* does not guarantee serialization upon itself, allowing a race where latter
* acquirers finish mutex_unlock before former ones.
*
* The race renders it unsafe to be used for serializing the freeing of an
* object in which the mutex is embedded, where the latter acquirer could go
* on to free the object while the former one is still doing mutex_unlock and
* causing memory corruption.
*
* However, there are many places in ZFS where the mutex is used for
* serializing object freeing, and the code is shared among other OSes without
* this issue. Thus, we need the spinlock to force the serialization on
* mutex_exit().
*
* See http://lwn.net/Articles/575477/ for the information about the race.
*/
#define mutex_exit(mp) \
{ \
ASSERT3P(mutex_owner(mp), ==, current); \
spl_mutex_clear_owner(mp); \
spin_lock(&(mp)->m_lock); \
spl_mutex_lockdep_off_maybe(mp); \
mutex_unlock(MUTEX(mp)); \
spl_mutex_lockdep_on_maybe(mp); \
spin_unlock(&(mp)->m_lock); \
/* NOTE: do not dereference mp after this point */ \
}
Reimplement mutexs for Linux lock profiling/analysis For a generic explanation of why mutexs needed to be reimplemented to work with the kernel lock profiling see commits: e811949a57044d60d12953c5c3b808a79a7d36ef and d28db80fd0fd4fd63aec09037c44408e51a222d6 The specific changes made to the mutex implemetation are as follows. The Linux mutex structure is now directly embedded in the kmutex_t. This allows a kmutex_t to be directly case to a mutex struct and passed directly to the Linux primative. Just like with the rwlocks it is critical that these functions be implemented as '#defines to ensure the location information is preserved. The preprocessor can then do a direct replacement of the Solaris primative with the linux primative. Just as with the rwlocks we need to track the lock owner. Here things get a little more interesting because depending on your kernel version, and how you've built your kernel Linux may already do this for you. If your running a 2.6.29 or newer kernel on a SMP system the lock owner will be tracked. This was added to Linux to support adaptive mutexs, more on that shortly. Alternately, your kernel might track the lock owner if you've set CONFIG_DEBUG_MUTEXES in the kernel build. If neither of the above things is true for your kernel the kmutex_t type will include and track the lock owner to ensure correct behavior. This is all handled by a new autoconf check called SPL_AC_MUTEX_OWNER. Concerning adaptive mutexs these are a very recent development and they did not make it in to either the latest FC11 of SLES11 kernels. Ideally, I'd love to see this kernel change appear in one of these distros because it does help performance. From Linux kernel commit: 0d66bf6d3514b35eb6897629059443132992dbd7 "Testing with Ingo's test-mutex application... gave a 345% boost for VFS scalability on my testbox" However, if you don't want to backport this change yourself you can still simply export the task_curr() symbol. The kmutex_t implementation will use this symbol when it's available to provide it's own adaptive mutexs. Finally, DEBUG_MUTEX support was removed including the proc handlers. This was done because now that we are cleanly integrated with the kernel profiling all this information and much much more is available in debug kernel builds. This code was now redundant. Update mutexs validated on: - SLES10 (ppc64) - SLES11 (x86_64) - CHAOS4.2 (x86_64) - RHEL5.3 (x86_64) - RHEL6 (x86_64) - FC11 (x86_64)
2009-09-25 21:47:01 +00:00
#endif /* _SPL_MUTEX_H */