mirror_zfs/include/spl/sys/condvar.h
Don Brady 186898bbb5 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
2019-06-22 16:51:46 -07:00

84 lines
3.2 KiB
C

/*
* 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>
#include <sys/kmem.h>
#include <sys/mutex.h>
#include <sys/callo.h>
#include <sys/wait.h>
#include <sys/time.h>
/*
* 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 *);
extern int __cv_wait_io_sig(kcondvar_t *, kmutex_t *);
extern int __cv_wait_sig(kcondvar_t *, kmutex_t *);
extern clock_t __cv_timedwait(kcondvar_t *, kmutex_t *, clock_t);
extern clock_t __cv_timedwait_io(kcondvar_t *, kmutex_t *, clock_t);
extern clock_t __cv_timedwait_sig(kcondvar_t *, kmutex_t *, clock_t);
extern clock_t cv_timedwait_hires(kcondvar_t *, kmutex_t *, hrtime_t,
hrtime_t res, int flag);
extern clock_t 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)
#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_wait_interruptible(cvp, mp) cv_wait_sig(cvp, mp)
#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)
#define cv_timedwait_interruptible(cvp, mp, t) cv_timedwait_sig(cvp, mp, t)
#define cv_signal(cvp) __cv_signal(cvp)
#define cv_broadcast(cvp) __cv_broadcast(cvp)
#endif /* _SPL_CONDVAR_H */