/*
 * Copyright (c) 2018-2022, NVIDIA CORPORATION.  All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include <nvgpu/bug.h>
#include <nvgpu/thread.h>
#include <nvgpu/barrier.h>
#include <nvgpu/os_sched.h>
#ifdef NVGPU_UNITTEST_FAULT_INJECTION_ENABLEMENT
#include <nvgpu/posix/posix-fault-injection.h>
#endif

#ifdef NVGPU_UNITTEST_FAULT_INJECTION_ENABLEMENT
struct nvgpu_posix_fault_inj *nvgpu_thread_get_fault_injection(void)
{
	struct nvgpu_posix_fault_inj_container *c =
			nvgpu_posix_fault_injection_get_container();

	return &c->thread_fi;
}

struct nvgpu_posix_fault_inj
			*nvgpu_thread_running_true_get_fault_injection(void)
{
	struct nvgpu_posix_fault_inj_container *c =
			nvgpu_posix_fault_injection_get_container();

	return &c->thread_running_true_fi;
}

struct nvgpu_posix_fault_inj *nvgpu_thread_serial_get_fault_injection(void)
{
	struct nvgpu_posix_fault_inj_container *c =
			nvgpu_posix_fault_injection_get_container();

	return &c->thread_serial_fi;
}
#endif

/**
 * Use pthreads to mostly emulate the Linux kernel APIs. There are some things
 * that are quite different - especially the stop/should_stop notions. In user
 * space threads can send signals to one another but of course within the kernel
 * that is not as simple.
 *
 * This could use some nice debugging some day as well.
 */
static void *nvgpu_posix_thread_wrapper(void *data)
{
	long ret;

	struct nvgpu_posix_thread_data *nvgpu =
				(struct nvgpu_posix_thread_data *)data;

#ifdef NVGPU_UNITTEST_FAULT_INJECTION_ENABLEMENT
	/* setup the fault injection container from the parent */
	nvgpu_posix_init_fault_injection(nvgpu->fi_container);
#endif

	nvgpu_smp_rmb();

	ret = nvgpu->fn(nvgpu->data);

	if (ret != 0L) {
		nvgpu_info(NULL, "Error %ld return from thread: %d",
				ret, nvgpu_current_tid(NULL));
	}

	return NULL;
}

static void nvgpu_thread_cancel_sync(struct nvgpu_thread *thread)
{
	int err;

	err = pthread_cancel(thread->thread);
	if (err != 0) {
		nvgpu_info(NULL, "Thread cancel error");
	}
}

int nvgpu_thread_create(struct nvgpu_thread *thread,
			void *data,
			int (*threadfn)(void *data), const char *name)
{
	pthread_attr_t attr;
	int ret;

#ifdef NVGPU_UNITTEST_FAULT_INJECTION_ENABLEMENT
	if (nvgpu_posix_fault_injection_handle_call(
				nvgpu_thread_get_fault_injection())) {
		return -EINVAL;
	}
#endif

	(void) memset(thread, 0, sizeof(*thread));

	/*
	 * By subtracting 1 the above memset ensures that we have a zero
	 * terminated string.
	 */
	if (name != NULL) {
		(void) strncpy(thread->tname, name,
			NVGPU_THREAD_POSIX_MAX_NAMELEN - 1);
	}

	thread->nvgpu.data = data;
	thread->nvgpu.fn = threadfn;
#ifdef NVGPU_UNITTEST_FAULT_INJECTION_ENABLEMENT
	/* pass the fault injection container to the child */
	thread->nvgpu.fi_container =
				nvgpu_posix_fault_injection_get_container();
#endif

	nvgpu_atomic_set(&thread->running, 1);
	ret = pthread_attr_init(&attr);
	if (ret != 0) {
		return ret;
	}

	ret = pthread_create(&thread->thread, &attr,
			     nvgpu_posix_thread_wrapper,
			     &thread->nvgpu);
	if (ret != 0) {
		if ((pthread_attr_destroy(&attr)) != 0) {
			nvgpu_info(NULL, "Thread attr destroy error");
		}
		return ret;
	}

#ifdef _GNU_SOURCE
	pthread_setname_np(thread->thread, thread->tname);
#endif

	ret = pthread_attr_destroy(&attr);
	if (ret != 0) {
		if ((pthread_cancel(thread->thread)) != 0) {
			nvgpu_info(NULL, "Thread cancel error");
		}
		return ret;
	}

#ifdef NVGPU_UNITTEST_FAULT_INJECTION_ENABLEMENT
	/*
	 * For some code that is tested using public APIs it's not safe for the
	 * parent thread to continue while the child thread is running. Fault
	 * injection per thread pointer points to the same container for both
	 * parent thread as well as the created one. So, there is chance of a
	 * race in fault injection functionality. Serialize the run so that race
	 * can be mitigated. Caller of nvgpu_thread_create() API should ensure
	 * that the created thread is stopped using some fault injection or
	 * otherwise.
	 */
	if (nvgpu_posix_fault_injection_handle_call(
				nvgpu_thread_serial_get_fault_injection())) {
		if ((pthread_join(thread->thread, NULL)) != 0) {
			nvgpu_info(NULL, "Thread join error");
		}
	}
#endif

	return 0;
}

int nvgpu_thread_create_priority(struct nvgpu_thread *thread,
			void *data, int (*threadfn)(void *data),
			int priority, const char *name)
{
	pthread_attr_t attr;
	struct sched_param param;
	int ret;

#ifdef NVGPU_UNITTEST_FAULT_INJECTION_ENABLEMENT
	if (nvgpu_posix_fault_injection_handle_call(
				nvgpu_thread_get_fault_injection())) {
		return -EINVAL;
	}
#endif

	(void) memset(thread, 0, sizeof(*thread));
	(void) memset(&param, 0, sizeof(struct sched_param));

	/*
	 * By subtracting 1 the above memset ensures that we have a zero
	 * terminated string.
	 */
	if (name != NULL) {
		(void) strncpy(thread->tname, name,
			NVGPU_THREAD_POSIX_MAX_NAMELEN - 1);
	}

	thread->nvgpu.data = data;
	thread->nvgpu.fn = threadfn;
#ifdef NVGPU_UNITTEST_FAULT_INJECTION_ENABLEMENT
	/* pass the fault injection container to the child */
	thread->nvgpu.fi_container =
				nvgpu_posix_fault_injection_get_container();
#endif

	nvgpu_atomic_set(&thread->running, 1);

	ret = pthread_attr_init(&attr);
	if (ret != 0) {
		return ret;
	}

	ret = pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
	if (ret != 0) {
		goto attr_destroy;
	}

	ret = pthread_attr_setschedpolicy(&attr, SCHED_RR);
	if (ret != 0) {
		goto attr_destroy;
	}

	param.sched_priority = priority;
	ret = pthread_attr_setschedparam(&attr, &param);
	if (ret != 0) {
		goto attr_destroy;
	}

	ret = pthread_create(&thread->thread, &attr,
			nvgpu_posix_thread_wrapper, &thread->nvgpu);
	if (ret != 0) {
		goto attr_destroy;
	}

#ifdef _GNU_SOURCE
	pthread_setname_np(thread->thread, thread->tname);
#endif

	ret = pthread_attr_destroy(&attr);
	if (ret != 0) {
		if ((pthread_cancel(thread->thread)) != 0) {
			nvgpu_info(NULL, "Thread cancel error");
		}
		return ret;
	}

#ifdef NVGPU_UNITTEST_FAULT_INJECTION_ENABLEMENT
	/*
	 * For some code that is tested using public APIs it's not safe for the
	 * parent thread to continue while the child thread is running. Fault
	 * injection per thread pointer points to the same container for both
	 * parent thread as well as the created one. So, there is chance of a
	 * race in fault injection functionality. Serialize the run so that race
	 * can be mitigated. Caller of nvgpu_thread_create() API should ensure
	 * that the created thread is stopped using some fault injection or
	 * otherwise.
	 */
	if (nvgpu_posix_fault_injection_handle_call(
				nvgpu_thread_serial_get_fault_injection())) {
		(void) pthread_join(thread->thread, NULL);
	}
#endif

	return 0;

attr_destroy:
	if ((pthread_attr_destroy(&attr)) != 0) {
		nvgpu_info(NULL, "Thread attr destroy error");
	}

	return ret;
}

void nvgpu_thread_stop(struct nvgpu_thread *thread)
{
	int old = nvgpu_atomic_cmpxchg(&thread->running, 1, 0);

	if (old != 0) {
		nvgpu_thread_cancel_sync(thread);
		nvgpu_thread_join(thread);
	}
}

void nvgpu_thread_stop_graceful(struct nvgpu_thread *thread,
		void (*thread_stop_fn)(void *data), void *data)
{
	int old = nvgpu_atomic_cmpxchg(&thread->running, 1, 0);

	if (old != 0) {
		if (thread_stop_fn != NULL) {
			thread_stop_fn(data);
		}
		nvgpu_thread_join(thread);
	}
}

bool nvgpu_thread_should_stop(struct nvgpu_thread *thread)
{
#ifdef NVGPU_UNITTEST_FAULT_INJECTION_ENABLEMENT
	if (nvgpu_posix_fault_injection_handle_call(
				nvgpu_thread_get_fault_injection())) {
		return true;
	}
#endif

	return (nvgpu_atomic_read(&thread->running) == 0);
}

bool nvgpu_thread_is_running(struct nvgpu_thread *thread)
{
#ifdef NVGPU_UNITTEST_FAULT_INJECTION_ENABLEMENT
	if (nvgpu_posix_fault_injection_handle_call(
			nvgpu_thread_running_true_get_fault_injection())) {
		return true;
	}
#endif
	return (nvgpu_atomic_read(&thread->running) == 1);
}

void nvgpu_thread_join(struct nvgpu_thread *thread)
{
	int err;

	err = pthread_join(thread->thread, NULL);
	if(err != 0 && err != ESRCH) {
		BUG();
	}
}