mirror_zfs/include/os/linux/spl/sys/condvar.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.
* For details, see <http://zfsonlinux.org/>.
*
* 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_CONDVAR_H
#define _SPL_CONDVAR_H
#include <linux/module.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)
2009-09-26 01:47:01 +04:00
#include <sys/kmem.h>
#include <sys/mutex.h>
#include <sys/callo.h>
#include <sys/wait.h>
#include <sys/time.h>
/*
* cv_timedwait() is similar to cv_wait() except that it additionally expects
* a timeout value specified in ticks. When woken by cv_signal() or
* cv_broadcast() it returns 1, otherwise when the timeout is reached -1 is
* returned.
*
* cv_timedwait_sig() behaves the same as cv_timedwait() but blocks
* interruptibly and can be woken by a signal (EINTR, ERESTART). When
* this occurs 0 is returned.
*
* cv_timedwait_io() and cv_timedwait_sig_io() are variants of cv_timedwait()
* and cv_timedwait_sig() which should be used when waiting for outstanding
* IO to complete. They are responsible for updating the iowait accounting
* when this is supported by the platform.
*
* cv_timedwait_hires() and cv_timedwait_sig_hires() are high resolution
* versions of cv_timedwait() and cv_timedwait_sig(). They expect the timeout
* to be specified as a hrtime_t allowing for timeouts of less than a tick.
*
* N.B. The return values differ slightly from the illumos implementation
* which returns the time remaining, instead of 1, when woken. They both
* return -1 on timeout. Consumers which need to know the time remaining
* are responsible for tracking it themselves.
*/
/*
* The kcondvar_t struct is protected by mutex taken externally before
* calling any of the wait/signal funs, and passed into the wait funs.
*/
#define CV_MAGIC 0x346545f4
#define CV_DESTROY 0x346545f5
typedef struct {
int cv_magic;
spl_wait_queue_head_t cv_event;
spl_wait_queue_head_t cv_destroy;
atomic_t cv_refs;
atomic_t cv_waiters;
kmutex_t *cv_mutex;
} kcondvar_t;
typedef enum { CV_DEFAULT = 0, CV_DRIVER } kcv_type_t;
extern void __cv_init(kcondvar_t *, char *, kcv_type_t, void *);
extern void __cv_destroy(kcondvar_t *);
extern void __cv_wait(kcondvar_t *, kmutex_t *);
extern void __cv_wait_io(kcondvar_t *, kmutex_t *);
OpenZFS 9425 - channel programs can be interrupted Problem Statement ================= ZFS Channel program scripts currently require a timeout, so that hung or long-running scripts return a timeout error instead of causing ZFS to get wedged. This limit can currently be set up to 100 million Lua instructions. Even with a limit in place, it would be desirable to have a sys admin (support engineer) be able to cancel a script that is taking a long time. Proposed Solution ================= Make it possible to abort a channel program by sending an interrupt signal.In the underlying txg_wait_sync function, switch the cv_wait to a cv_wait_sig to catch the signal. Once a signal is encountered, the dsl_sync_task function can install a Lua hook that will get called before the Lua interpreter executes a new line of code. The dsl_sync_task can resume with a standard txg_wait_sync call and wait for the txg to complete. Meanwhile, the hook will abort the script and indicate that the channel program was canceled. The kernel returns a EINTR to indicate that the channel program run was canceled. Porting notes: Added missing return value from cv_wait_sig() Authored by: Don Brady <don.brady@delphix.com> Reviewed by: Sebastien Roy <sebastien.roy@delphix.com> Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com> Reviewed by: Matt Ahrens <matt@delphix.com> Reviewed by: Sara Hartse <sara.hartse@delphix.com> Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov> Approved by: Robert Mustacchi <rm@joyent.com> Ported-by: Don Brady <don.brady@delphix.com> Signed-off-by: Don Brady <don.brady@delphix.com> OpenZFS-issue: https://www.illumos.org/issues/9425 OpenZFS-commit: https://github.com/illumos/illumos-gate/commit/d0cb1fb926 Closes #8904
2019-06-23 02:51:46 +03:00
extern int __cv_wait_io_sig(kcondvar_t *, kmutex_t *);
extern int __cv_wait_sig(kcondvar_t *, kmutex_t *);
extern int __cv_timedwait(kcondvar_t *, kmutex_t *, clock_t);
extern int __cv_timedwait_io(kcondvar_t *, kmutex_t *, clock_t);
extern int __cv_timedwait_sig(kcondvar_t *, kmutex_t *, clock_t);
extern int cv_timedwait_hires(kcondvar_t *, kmutex_t *, hrtime_t,
hrtime_t res, int flag);
extern int cv_timedwait_sig_hires(kcondvar_t *, kmutex_t *, hrtime_t,
hrtime_t res, int flag);
extern void __cv_signal(kcondvar_t *);
extern void __cv_broadcast(kcondvar_t *c);
#define cv_init(cvp, name, type, arg) __cv_init(cvp, name, type, arg)
#define cv_destroy(cvp) __cv_destroy(cvp)
#define cv_wait(cvp, mp) __cv_wait(cvp, mp)
#define cv_wait_io(cvp, mp) __cv_wait_io(cvp, mp)
OpenZFS 9425 - channel programs can be interrupted Problem Statement ================= ZFS Channel program scripts currently require a timeout, so that hung or long-running scripts return a timeout error instead of causing ZFS to get wedged. This limit can currently be set up to 100 million Lua instructions. Even with a limit in place, it would be desirable to have a sys admin (support engineer) be able to cancel a script that is taking a long time. Proposed Solution ================= Make it possible to abort a channel program by sending an interrupt signal.In the underlying txg_wait_sync function, switch the cv_wait to a cv_wait_sig to catch the signal. Once a signal is encountered, the dsl_sync_task function can install a Lua hook that will get called before the Lua interpreter executes a new line of code. The dsl_sync_task can resume with a standard txg_wait_sync call and wait for the txg to complete. Meanwhile, the hook will abort the script and indicate that the channel program was canceled. The kernel returns a EINTR to indicate that the channel program run was canceled. Porting notes: Added missing return value from cv_wait_sig() Authored by: Don Brady <don.brady@delphix.com> Reviewed by: Sebastien Roy <sebastien.roy@delphix.com> Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com> Reviewed by: Matt Ahrens <matt@delphix.com> Reviewed by: Sara Hartse <sara.hartse@delphix.com> Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov> Approved by: Robert Mustacchi <rm@joyent.com> Ported-by: Don Brady <don.brady@delphix.com> Signed-off-by: Don Brady <don.brady@delphix.com> OpenZFS-issue: https://www.illumos.org/issues/9425 OpenZFS-commit: https://github.com/illumos/illumos-gate/commit/d0cb1fb926 Closes #8904
2019-06-23 02:51:46 +03:00
#define cv_wait_io_sig(cvp, mp) __cv_wait_io_sig(cvp, mp)
#define cv_wait_sig(cvp, mp) __cv_wait_sig(cvp, mp)
#define cv_signal(cvp) __cv_signal(cvp)
#define cv_broadcast(cvp) __cv_broadcast(cvp)
/*
* NB: There is no way to reliably distinguish between having been signalled
* and having timed out on Linux. If the client code needs to reliably
* distinguish between the two it should use the hires variant.
*/
#define cv_timedwait(cvp, mp, t) __cv_timedwait(cvp, mp, t)
#define cv_timedwait_io(cvp, mp, t) __cv_timedwait_io(cvp, mp, t)
#define cv_timedwait_sig(cvp, mp, t) __cv_timedwait_sig(cvp, mp, t)
#endif /* _SPL_CONDVAR_H */