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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Minios-devel] [UNIKRAFT PATCH 4/5] lib/uklock: Introduce libuklock
Just adding a couple of minor notes
Sharan Santhanam <sharan.santhanam@xxxxxxxxx> writes:
> We provide implementation for 2 type of synchronization primitives
> * Semaphore
> * Mutex
>
> Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
> Signed-off-by: Sharan Santhanam <sharan.santhanam@xxxxxxxxx>
> ---
> lib/Config.uk | 1 +
> lib/Makefile.uk | 1 +
> lib/uklock/Config.uk | 22 ++++++
> lib/uklock/Makefile.uk | 7 ++
> lib/uklock/export.syms | 2 +
> lib/uklock/include/uk/mutex.h | 120 ++++++++++++++++++++++++++++++
> lib/uklock/include/uk/semaphore.h | 153
> ++++++++++++++++++++++++++++++++++++++
> lib/uklock/mutex.c | 9 +++
> lib/uklock/semaphore.c | 12 +++
> 9 files changed, 327 insertions(+)
> create mode 100644 lib/uklock/Config.uk
> create mode 100644 lib/uklock/Makefile.uk
> create mode 100644 lib/uklock/export.syms
> create mode 100644 lib/uklock/include/uk/mutex.h
> create mode 100644 lib/uklock/include/uk/semaphore.h
> create mode 100644 lib/uklock/mutex.c
> create mode 100644 lib/uklock/semaphore.c
>
> diff --git a/lib/Config.uk b/lib/Config.uk
> index 0a78a02..9e6b269 100644
> --- a/lib/Config.uk
> +++ b/lib/Config.uk
> @@ -33,4 +33,5 @@ source "lib/ukallocbbuddy/Config.uk"
> source "lib/uksched/Config.uk"
> source "lib/ukschedcoop/Config.uk"
> source "lib/fdt/Config.uk"
> +source "lib/uklock/Config.uk"
> source "lib/ukswrand/Config.uk"
> diff --git a/lib/Makefile.uk b/lib/Makefile.uk
> index d549152..a79ad0d 100644
> --- a/lib/Makefile.uk
> +++ b/lib/Makefile.uk
> @@ -16,3 +16,4 @@ $(eval $(call _import_lib,$(CONFIG_UK_BASE)/lib/uksched))
> $(eval $(call _import_lib,$(CONFIG_UK_BASE)/lib/ukschedcoop))
> $(eval $(call _import_lib,$(CONFIG_UK_BASE)/lib/fdt))
> $(eval $(call _import_lib,$(CONFIG_UK_BASE)/lib/vfscore))
> +$(eval $(call _import_lib,$(CONFIG_UK_BASE)/lib/uklock))
> diff --git a/lib/uklock/Config.uk b/lib/uklock/Config.uk
> new file mode 100644
> index 0000000..984e348
> --- /dev/null
> +++ b/lib/uklock/Config.uk
> @@ -0,0 +1,22 @@
> +menuconfig LIBUKLOCK
> + bool "uklock: Multi-task synchronization primitives"
> + select LIBUKDEBUG
> + select LIBUKALLOC
> + select LIBUKSCHED
> + select LIBUKSEMAPHORE
> + select LIBUKMUTEX
> + default n
> +
> +if LIBUKLOCK
> + config LIBUKSEMAPHORE
> + bool "Semaphore"
> + default y
> + help
> + Enable semaphore based synchornization
> +
> + config LIBUKMUTEX
> + bool "Mutex"
> + default y
> + help
> + Enable mutex based synchornization
> +endif
> diff --git a/lib/uklock/Makefile.uk b/lib/uklock/Makefile.uk
> new file mode 100644
> index 0000000..1b15524
> --- /dev/null
> +++ b/lib/uklock/Makefile.uk
> @@ -0,0 +1,7 @@
> +$(eval $(call addlib_s,libuklock,$(CONFIG_LIBUKLOCK)))
> +
> +CINCLUDES-$(CONFIG_LIBUKLOCK) += -I$(LIBUKLOCK_BASE)/include
> +CXXINCLUDES-$(CONFIG_LIBUKLOCK) += -I$(LIBUKLOCK_BASE)/include
> +
> +LIBUKLOCK_SRCS-$(CONFIG_LIBUKSEMAPHORE) += $(LIBUKLOCK_BASE)/semaphore.c
> +LIBUKLOCK_SRCS-$(CONFIG_LIBUKMUTEX) += $(LIBUKLOCK_BASE)/mutex.c
> diff --git a/lib/uklock/export.syms b/lib/uklock/export.syms
> new file mode 100644
> index 0000000..bbb4d12
> --- /dev/null
> +++ b/lib/uklock/export.syms
> @@ -0,0 +1,2 @@
> +uk_semaphore_init
> +uk_mutex_init
> diff --git a/lib/uklock/include/uk/mutex.h b/lib/uklock/include/uk/mutex.h
> new file mode 100644
> index 0000000..0a03a08
> --- /dev/null
> +++ b/lib/uklock/include/uk/mutex.h
> @@ -0,0 +1,120 @@
> +/* SPDX-License-Identifier: BSD-3-Clause */
> +/*
> + * Authors: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
> + *
> + * Copyright (c) 2018, NEC Europe Ltd., NEC Corporation. All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + *
> + * 1. Redistributions of source code must retain the above copyright
> + * notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + * notice, this list of conditions and the following disclaimer in the
> + * documentation and/or other materials provided with the distribution.
> + * 3. Neither the name of the copyright holder nor the names of its
> + * contributors may be used to endorse or promote products derived from
> + * this software without specific prior written permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
> IS"
> + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
> + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
> + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
> + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
> + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
> + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
> + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
> + * POSSIBILITY OF SUCH DAMAGE.
> + *
> + * THIS HEADER MAY NOT BE EXTRACTED OR MODIFIED IN ANY WAY.
> + */
> +
> +#ifndef __UK_MUTEX_H__
> +#define __UK_MUTEX_H__
> +
> +#include <uk/config.h>
> +#if CONFIG_LIBUKMUTEX
> +
> +#include <uk/assert.h>
> +#include <uk/plat/lcpu.h>
> +#ifdef CONFIG_LIBUKSCHED
> +#include <uk/thread.h>
> +#include <uk/wait.h>
> +#include <uk/wait_types.h>
> +#include <uk/plat/time.h>
> +#endif /* CONFIG_LIBUKSCHED */
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +#ifdef CONFIG_LIBUKSCHED
> +
> +/*
> + * Mutex that relies on a scheduler
> + * uses wait queues for threads
> + */
> +struct uk_mutex
> +{
> + int locked;
> + struct uk_waitq wait;
> +};
> +
> +void uk_mutex_init(struct uk_mutex *m);
> +
> +static inline void uk_mutex_hold(struct uk_mutex *m)
> +{
> + unsigned long irqf;
> +
> + UK_ASSERT(m);
> +
> + for (;;) {
> + uk_waitq_wait_event(&m->wait, m->locked == 0);
> + irqf = ukplat_lcpu_save_irqf();
> + if (!m->locked)
> + break;
> + ukplat_lcpu_restore_irqf(irqf);
> + }
> + m->locked = 1;
No need to change anything about it. But potentially memory barrier is needed
here,
if we want SMP. Just for the mental note. Or use atomic insteand
> + ukplat_lcpu_restore_irqf(irqf);
> +}
> +
> +static inline int uk_mutex_hold_try(struct uk_mutex *m)
> +{
> + unsigned long irqf;
> + int ret = 0;
> +
> + UK_ASSERT(m);
> +
> + irqf = ukplat_lcpu_save_irqf();
> + if (!m->locked)
> + ret = m->locked = 1;
> + ukplat_lcpu_restore_irqf(irqf);
> + return ret;
> +}
> +
> +static inline void uk_mutex_release(struct uk_mutex *m)
> +{
> + unsigned long irqf;
> +
> + UK_ASSERT(m);
> +
> + irqf = ukplat_lcpu_save_irqf();
> + UK_ASSERT(m->locked);
> + m->locked = 0;
> + uk_waitq_wake_up(&m->wait);
> + ukplat_lcpu_restore_irqf(irqf);
> +}
> +
> +#endif /* CONFIG_LIBUKSCHED */
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* CONFIG_LIBUKMUTEX */
> +
> +#endif /* __UK_MUTEX_H__ */
> diff --git a/lib/uklock/include/uk/semaphore.h
> b/lib/uklock/include/uk/semaphore.h
> new file mode 100644
> index 0000000..d344e87
> --- /dev/null
> +++ b/lib/uklock/include/uk/semaphore.h
> @@ -0,0 +1,153 @@
> +/* SPDX-License-Identifier: BSD-2-Clause */
> +/*
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + * notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + * notice, this list of conditions and the following disclaimer in the
> + * documentation and/or other materials provided with the distribution.
> + *
> + * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> + * ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
> + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
> + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
> + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
> + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
> + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
> + * SUCH DAMAGE.
> + */
> +/* Taken and modified from Mini-OS (include/semphore.h) */
> +#ifndef __UK_SEMAPHORE_H__
> +#define __UK_SEMAPHORE_H__
> +
> +#include <uk/config.h>
> +
> +#if CONFIG_LIBUKSEMAPHORE
> +
> +#include <uk/print.h>
> +#include <uk/assert.h>
> +#include <uk/plat/lcpu.h>
> +#if CONFIG_LIBUKSCHED
> +#include <uk/thread.h>
> +#include <uk/wait.h>
> +#include <uk/wait_types.h>
> +#include <uk/plat/time.h>
> +#endif
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +#if CONFIG_LIBUKSCHED
> +
> +/*
> + * Semaphore that relies on a scheduler
> + * uses wait queues for threads
> + */
> +struct uk_semaphore
> +{
> + long count;
> + struct uk_waitq wait;
> +};
> +
> +void uk_semaphore_init(struct uk_semaphore *s, long count);
> +
> +static inline void uk_semaphore_down(struct uk_semaphore *s)
> +{
> + unsigned long irqf;
> +
> + UK_ASSERT(s);
> +
> + for (;;) {
> + uk_waitq_wait_event(&s->wait, s->count > 0);
> + irqf = ukplat_lcpu_save_irqf();
> + if (s->count > 0)
> + break;
> + ukplat_lcpu_restore_irqf(irqf);
> + }
> + --s->count;
> + uk_printd(DLVL_INFO, "Decreased semaphore %p to %ld\n", s, s->count);
I would say this should be really the lowest debug level - DLVL_EXTRA
> + ukplat_lcpu_restore_irqf(irqf);
> +}
> +
> +static inline int uk_semaphore_down_try(struct uk_semaphore *s)
> +{
> + unsigned long irqf;
> + int ret = 0;
> +
> + UK_ASSERT(s);
> +
> + irqf = ukplat_lcpu_save_irqf();
> + if (s->count > 0) {
> + ret = 1;
> + --s->count;
> + uk_printd(DLVL_INFO, "Decreased semaphore %p to %ld\n",
> + s, s->count);
> + }
> + ukplat_lcpu_restore_irqf(irqf);
> + return ret;
> +}
> +
> +/* Returns __NSEC_MAX on timeout, expired time when down was successful */
> +static inline __nsec uk_semaphore_down_to(struct uk_semaphore *s,
> + __nsec timeout)
> +{
> + unsigned long irqf;
> + __nsec then = ukplat_monotonic_clock();
> + __nsec deadline;
> +
> + UK_ASSERT(s);
> +
> + if (timeout == 0)
> + deadline = 0;
> + else
> + deadline = then + timeout;
> +
> + for (;;) {
> + uk_waitq_wait_event_deadline(&s->wait, s->count > 0, deadline);
> + irqf = ukplat_lcpu_save_irqf();
> + if (s->count > 0 || (deadline &&
> + ukplat_monotonic_clock() >= deadline))
> + break;
> + ukplat_lcpu_restore_irqf(irqf);
> + }
> + if (s->count > 0) {
> + s->count--;
> + uk_printd(DLVL_INFO, "Decreased semaphore %p to %ld\n",
> + s, s->count);
> + ukplat_lcpu_restore_irqf(irqf);
> + return ukplat_monotonic_clock() - then;
> + }
> +
> + ukplat_lcpu_restore_irqf(irqf);
> + uk_printd(DLVL_INFO, "Timed out while waiting for semaphore %p\n", s);
> + return __NSEC_MAX;
> +}
> +
> +static inline void uk_semaphore_up(struct uk_semaphore *s)
> +{
> + unsigned long irqf;
> +
> + UK_ASSERT(s);
> +
> + irqf = ukplat_lcpu_save_irqf();
> + ++s->count;
> + uk_printd(DLVL_INFO, "Increased semaphore %p to %ld\n",
> + s, s->count);
> + uk_waitq_wake_up(&s->wait);
> + ukplat_lcpu_restore_irqf(irqf);
> +}
> +#endif
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* CONFIG_LIBUKSEMAPHORE */
> +
> +#endif /* __UK_SEMAPHORE_H__ */
> diff --git a/lib/uklock/mutex.c b/lib/uklock/mutex.c
> new file mode 100644
> index 0000000..be7413f
> --- /dev/null
> +++ b/lib/uklock/mutex.c
> @@ -0,0 +1,9 @@
> +#include <uk/mutex.h>
> +
> +#ifdef CONFIG_LIBUKSCHED
> +void uk_mutex_init(struct uk_mutex *m)
> +{
> + m->locked = 0;
> + uk_waitq_init(&m->wait);
> +}
> +#endif /* CONFIG_LIBUKSCHED */
> diff --git a/lib/uklock/semaphore.c b/lib/uklock/semaphore.c
> new file mode 100644
> index 0000000..aa084ea
> --- /dev/null
> +++ b/lib/uklock/semaphore.c
> @@ -0,0 +1,12 @@
> +#include <uk/semaphore.h>
> +
> +#ifdef CONFIG_LIBUKSCHED
> +void uk_semaphore_init(struct uk_semaphore *s, long count)
> +{
> + s->count = count;
> + uk_waitq_init(&s->wait);
> +
> + uk_printd(DLVL_INFO, "Initialized semaphore %p with %ld\n",
> + s, s->count);
> +}
> +#endif /* CONFIG_LIBUKSCHED */
> --
> 2.7.4
>
>
> _______________________________________________
> Minios-devel mailing list
> Minios-devel@xxxxxxxxxxxxxxxxxxxx
> https://lists.xenproject.org/mailman/listinfo/minios-devel
--
Yuri Volchkov
Software Specialist
NEC Europe Ltd
Kurfürsten-Anlage 36
D-69115 Heidelberg
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