drivers/gpu/drm/i915/i915_utils.h - linux/torvalds/linux - Git at Google

 /*
  * Copyright © 2016 Intel Corporation
  *
  * 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 (including the next
  * paragraph) 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.
  *
  */

 #ifndef __I915_UTILS_H
 #define __I915_UTILS_H

 #include <linux/list.h>
 #include <linux/overflow.h>
 #include <linux/sched.h>
 #include <linux/types.h>
 #include <linux/workqueue.h>

 struct drm_i915_private;
 struct timer_list;

 #undef WARN_ON
 /* Many gcc seem to no see through this and fall over :( */
 #if 0
 #define WARN_ON(x) ({ \
 	bool __i915_warn_cond = (x); \
 	if (__builtin_constant_p(__i915_warn_cond)) \
 		BUILD_BUG_ON(__i915_warn_cond); \
 	WARN(__i915_warn_cond, "WARN_ON(" #x ")"); })
 #else
 #define WARN_ON(x) WARN((x), "%s", "WARN_ON(" __stringify(x) ")")
 #endif

 #undef WARN_ON_ONCE
 #define WARN_ON_ONCE(x) WARN_ONCE((x), "%s", "WARN_ON_ONCE(" __stringify(x) ")")

 #define MISSING_CASE(x) WARN(1, "Missing case (%s == %ld)\n", \
 			     __stringify(x), (long)(x))

 void __printf(3, 4)
 __i915_printk(struct drm_i915_private *dev_priv, const char *level,
 	      const char *fmt, ...);

 #define i915_report_error(dev_priv, fmt, ...)				   \
 	__i915_printk(dev_priv, KERN_ERR, fmt, ##__VA_ARGS__)

 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG)

 int __i915_inject_probe_error(struct drm_i915_private *i915, int err,
 			      const char *func, int line);
 #define i915_inject_probe_error(_i915, _err) \
 	__i915_inject_probe_error((_i915), (_err), __func__, __LINE__)
 bool i915_error_injected(void);

 #else

 #define i915_inject_probe_error(i915, e) ({ BUILD_BUG_ON_INVALID(i915); 0; })
 #define i915_error_injected() false

 #endif

 #define i915_inject_probe_failure(i915) i915_inject_probe_error((i915), -ENODEV)

 #define i915_probe_error(i915, fmt, ...)				   \
 	__i915_printk(i915, i915_error_injected() ? KERN_DEBUG : KERN_ERR, \
 		      fmt, ##__VA_ARGS__)

 #if defined(GCC_VERSION) && GCC_VERSION >= 70000
 #define add_overflows_t(T, A, B) \
 	__builtin_add_overflow_p((A), (B), (T)0)
 #else
 #define add_overflows_t(T, A, B) ({ \
 	typeof(A) a = (A); \
 	typeof(B) b = (B); \
 	(T)(a + b) < a; \
 })
 #endif

 #define add_overflows(A, B) \
 	add_overflows_t(typeof((A) + (B)), (A), (B))

 #define range_overflows(start, size, max) ({ \
 	typeof(start) start__ = (start); \
 	typeof(size) size__ = (size); \
 	typeof(max) max__ = (max); \
 	(void)(&start__ == &size__); \
 	(void)(&start__ == &max__); \
 	start__ > max__ || size__ > max__ - start__; \
 })

 #define range_overflows_t(type, start, size, max) \
 	range_overflows((type)(start), (type)(size), (type)(max))

 /* Note we don't consider signbits :| */
 #define overflows_type(x, T) \
 	(sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T))

 static inline bool
 __check_struct_size(size_t base, size_t arr, size_t count, size_t *size)
 {
 	size_t sz;

 	if (check_mul_overflow(count, arr, &sz))
 		return false;

 	if (check_add_overflow(sz, base, &sz))
 		return false;

 	*size = sz;
 	return true;
 }

 /**
  * check_struct_size() - Calculate size of structure with trailing array.
  * @p: Pointer to the structure.
  * @member: Name of the array member.
  * @n: Number of elements in the array.
  * @sz: Total size of structure and array
  *
  * Calculates size of memory needed for structure @p followed by an
  * array of @n @member elements, like struct_size() but reports
  * whether it overflowed, and the resultant size in @sz
  *
  * Return: false if the calculation overflowed.
  */
 #define check_struct_size(p, member, n, sz) \
 	likely(__check_struct_size(sizeof(*(p)), \
 				   sizeof(*(p)->member) + __must_be_array((p)->member), \
 				   n, sz))

 #define ptr_mask_bits(ptr, n) ({					\
 	unsigned long __v = (unsigned long)(ptr);			\
 	(typeof(ptr))(__v & -BIT(n));					\
 })

 #define ptr_unmask_bits(ptr, n) ((unsigned long)(ptr) & (BIT(n) - 1))

 #define ptr_unpack_bits(ptr, bits, n) ({				\
 	unsigned long __v = (unsigned long)(ptr);			\
 	*(bits) = __v & (BIT(n) - 1);					\
 	(typeof(ptr))(__v & -BIT(n));					\
 })

 #define ptr_pack_bits(ptr, bits, n) ({					\
 	unsigned long __bits = (bits);					\
 	GEM_BUG_ON(__bits & -BIT(n));					\
 	((typeof(ptr))((unsigned long)(ptr) | __bits));			\
 })

 #define ptr_dec(ptr) ({							\
 	unsigned long __v = (unsigned long)(ptr);			\
 	(typeof(ptr))(__v - 1);						\
 })

 #define ptr_inc(ptr) ({							\
 	unsigned long __v = (unsigned long)(ptr);			\
 	(typeof(ptr))(__v + 1);						\
 })

 #define page_mask_bits(ptr) ptr_mask_bits(ptr, PAGE_SHIFT)
 #define page_unmask_bits(ptr) ptr_unmask_bits(ptr, PAGE_SHIFT)
 #define page_pack_bits(ptr, bits) ptr_pack_bits(ptr, bits, PAGE_SHIFT)
 #define page_unpack_bits(ptr, bits) ptr_unpack_bits(ptr, bits, PAGE_SHIFT)

 #define struct_member(T, member) (((T *)0)->member)

 #define ptr_offset(ptr, member) offsetof(typeof(*(ptr)), member)

 #define fetch_and_zero(ptr) ({						\
 	typeof(*ptr) __T = *(ptr);					\
 	*(ptr) = (typeof(*ptr))0;					\
 	__T;								\
 })

 /*
  * container_of_user: Extract the superclass from a pointer to a member.
  *
  * Exactly like container_of() with the exception that it plays nicely
  * with sparse for __user @ptr.
  */
 #define container_of_user(ptr, type, member) ({				\
 	void __user *__mptr = (void __user *)(ptr);			\
 	BUILD_BUG_ON_MSG(!__same_type(*(ptr), struct_member(type, member)) && \
 			 !__same_type(*(ptr), void),			\
 			 "pointer type mismatch in container_of()");	\
 	((type __user *)(__mptr - offsetof(type, member))); })

 /*
  * check_user_mbz: Check that a user value exists and is zero
  *
  * Frequently in our uABI we reserve space for future extensions, and
  * two ensure that userspace is prepared we enforce that space must
  * be zero. (Then any future extension can safely assume a default value
  * of 0.)
  *
  * check_user_mbz() combines checking that the user pointer is accessible
  * and that the contained value is zero.
  *
  * Returns: -EFAULT if not accessible, -EINVAL if !zero, or 0 on success.
  */
 #define check_user_mbz(U) ({						\
 	typeof(*(U)) mbz__;						\
 	get_user(mbz__, (U)) ? -EFAULT : mbz__ ? -EINVAL : 0;		\
 })

 static inline u64 ptr_to_u64(const void *ptr)
 {
 	return (uintptr_t)ptr;
 }

 #define u64_to_ptr(T, x) ({						\
 	typecheck(u64, x);						\
 	(T *)(uintptr_t)(x);						\
 })

 #define __mask_next_bit(mask) ({					\
 	int __idx = ffs(mask) - 1;					\
 	mask &= ~BIT(__idx);						\
 	__idx;								\
 })

 static inline bool is_power_of_2_u64(u64 n)
 {
 	return (n != 0 && ((n & (n - 1)) == 0));
 }

 static inline void __list_del_many(struct list_head *head,
 				   struct list_head *first)
 {
 	first->prev = head;
 	WRITE_ONCE(head->next, first);
 }

 /*
  * Wait until the work is finally complete, even if it tries to postpone
  * by requeueing itself. Note, that if the worker never cancels itself,
  * we will spin forever.
  */
 static inline void drain_delayed_work(struct delayed_work *dw)
 {
 	do {
 		while (flush_delayed_work(dw))
 			;
 	} while (delayed_work_pending(dw));
 }

 static inline unsigned long msecs_to_jiffies_timeout(const unsigned int m)
 {
 	unsigned long j = msecs_to_jiffies(m);

 	return min_t(unsigned long, MAX_JIFFY_OFFSET, j + 1);
 }

 /*
  * If you need to wait X milliseconds between events A and B, but event B
  * doesn't happen exactly after event A, you record the timestamp (jiffies) of
  * when event A happened, then just before event B you call this function and
  * pass the timestamp as the first argument, and X as the second argument.
  */
 static inline void
 wait_remaining_ms_from_jiffies(unsigned long timestamp_jiffies, int to_wait_ms)
 {
 	unsigned long target_jiffies, tmp_jiffies, remaining_jiffies;

 	/*
 	 * Don't re-read the value of "jiffies" every time since it may change
 	 * behind our back and break the math.
 	 */
 	tmp_jiffies = jiffies;
 	target_jiffies = timestamp_jiffies +
 			 msecs_to_jiffies_timeout(to_wait_ms);

 	if (time_after(target_jiffies, tmp_jiffies)) {
 		remaining_jiffies = target_jiffies - tmp_jiffies;
 		while (remaining_jiffies)
 			remaining_jiffies =
 			    schedule_timeout_uninterruptible(remaining_jiffies);
 	}
 }

 /**
  * __wait_for - magic wait macro
  *
  * Macro to help avoid open coding check/wait/timeout patterns. Note that it's
  * important that we check the condition again after having timed out, since the
  * timeout could be due to preemption or similar and we've never had a chance to
  * check the condition before the timeout.
  */
 #define __wait_for(OP, COND, US, Wmin, Wmax) ({ \
 	const ktime_t end__ = ktime_add_ns(ktime_get_raw(), 1000ll * (US)); \
 	long wait__ = (Wmin); /* recommended min for usleep is 10 us */	\
 	int ret__;							\
 	might_sleep();							\
 	for (;;) {							\
 		const bool expired__ = ktime_after(ktime_get_raw(), end__); \
 		OP;							\
 		/* Guarantee COND check prior to timeout */		\
 		barrier();						\
 		if (COND) {						\
 			ret__ = 0;					\
 			break;						\
 		}							\
 		if (expired__) {					\
 			ret__ = -ETIMEDOUT;				\
 			break;						\
 		}							\
 		usleep_range(wait__, wait__ * 2);			\
 		if (wait__ < (Wmax))					\
 			wait__ <<= 1;					\
 	}								\
 	ret__;								\
 })

 #define _wait_for(COND, US, Wmin, Wmax)	__wait_for(, (COND), (US), (Wmin), \
 						   (Wmax))
 #define wait_for(COND, MS)		_wait_for((COND), (MS) * 1000, 10, 1000)

 /* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */
 #if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT)
 # define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) WARN_ON_ONCE((ATOMIC) && !in_atomic())
 #else
 # define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) do { } while (0)
 #endif

 #define _wait_for_atomic(COND, US, ATOMIC) \
 ({ \
 	int cpu, ret, timeout = (US) * 1000; \
 	u64 base; \
 	_WAIT_FOR_ATOMIC_CHECK(ATOMIC); \
 	if (!(ATOMIC)) { \
 		preempt_disable(); \
 		cpu = smp_processor_id(); \
 	} \
 	base = local_clock(); \
 	for (;;) { \
 		u64 now = local_clock(); \
 		if (!(ATOMIC)) \
 			preempt_enable(); \
 		/* Guarantee COND check prior to timeout */ \
 		barrier(); \
 		if (COND) { \
 			ret = 0; \
 			break; \
 		} \
 		if (now - base >= timeout) { \
 			ret = -ETIMEDOUT; \
 			break; \
 		} \
 		cpu_relax(); \
 		if (!(ATOMIC)) { \
 			preempt_disable(); \
 			if (unlikely(cpu != smp_processor_id())) { \
 				timeout -= now - base; \
 				cpu = smp_processor_id(); \
 				base = local_clock(); \
 			} \
 		} \
 	} \
 	ret; \
 })

 #define wait_for_us(COND, US) \
 ({ \
 	int ret__; \
 	BUILD_BUG_ON(!__builtin_constant_p(US)); \
 	if ((US) > 10) \
 		ret__ = _wait_for((COND), (US), 10, 10); \
 	else \
 		ret__ = _wait_for_atomic((COND), (US), 0); \
 	ret__; \
 })

 #define wait_for_atomic_us(COND, US) \
 ({ \
 	BUILD_BUG_ON(!__builtin_constant_p(US)); \
 	BUILD_BUG_ON((US) > 50000); \
 	_wait_for_atomic((COND), (US), 1); \
 })

 #define wait_for_atomic(COND, MS) wait_for_atomic_us((COND), (MS) * 1000)

 #define KHz(x) (1000 * (x))
 #define MHz(x) KHz(1000 * (x))

 #define KBps(x) (1000 * (x))
 #define MBps(x) KBps(1000 * (x))
 #define GBps(x) ((u64)1000 * MBps((x)))

 static inline const char *yesno(bool v)
 {
 	return v ? "yes" : "no";
 }

 static inline const char *onoff(bool v)
 {
 	return v ? "on" : "off";
 }

 static inline const char *enableddisabled(bool v)
 {
 	return v ? "enabled" : "disabled";
 }

 static inline void add_taint_for_CI(unsigned int taint)
 {
 	/*
 	 * The system is "ok", just about surviving for the user, but
 	 * CI results are now unreliable as the HW is very suspect.
 	 * CI checks the taint state after every test and will reboot
 	 * the machine if the kernel is tainted.
 	 */
 	add_taint(taint, LOCKDEP_STILL_OK);
 }

 void cancel_timer(struct timer_list *t);
 void set_timer_ms(struct timer_list *t, unsigned long timeout);

 static inline bool timer_expired(const struct timer_list *t)
 {
 	return READ_ONCE(t->expires) && !timer_pending(t);
 }

 /*
  * This is a lookalike for IS_ENABLED() that takes a kconfig value,
  * e.g. CONFIG_DRM_I915_SPIN_REQUEST, and evaluates whether it is non-zero
  * i.e. whether the configuration is active. Wrapping up the config inside
  * a boolean context prevents clang and smatch from complaining about potential
  * issues in confusing logical-&& with bitwise-& for constants.
  *
  * Sadly IS_ENABLED() itself does not work with kconfig values.
  *
  * Returns 0 if @config is 0, 1 if set to any value.
  */
 #define IS_ACTIVE(config) ((config) != 0)

 #endif /* !__I915_UTILS_H */
	/*
	* Copyright © 2016 Intel Corporation
	*
	* 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 (including the next
	* paragraph) 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.
	*
	*/

	#ifndef __I915_UTILS_H
	#define __I915_UTILS_H

	#include <linux/list.h>
	#include <linux/overflow.h>
	#include <linux/sched.h>
	#include <linux/types.h>
	#include <linux/workqueue.h>

	struct drm_i915_private;
	struct timer_list;

	#undef WARN_ON
	/* Many gcc seem to no see through this and fall over :( */
	#if 0
	#define WARN_ON(x) ({ \
	bool __i915_warn_cond = (x); \
	if (__builtin_constant_p(__i915_warn_cond)) \
	BUILD_BUG_ON(__i915_warn_cond); \
	WARN(__i915_warn_cond, "WARN_ON(" #x ")"); })
	#else
	#define WARN_ON(x) WARN((x), "%s", "WARN_ON(" __stringify(x) ")")
	#endif

	#undef WARN_ON_ONCE
	#define WARN_ON_ONCE(x) WARN_ONCE((x), "%s", "WARN_ON_ONCE(" __stringify(x) ")")

	#define MISSING_CASE(x) WARN(1, "Missing case (%s == %ld)\n", \
	__stringify(x), (long)(x))

	void __printf(3, 4)
	__i915_printk(struct drm_i915_private dev_priv, const char level,
	const char *fmt, ...);

	#define i915_report_error(dev_priv, fmt, ...) \
	__i915_printk(dev_priv, KERN_ERR, fmt, ##__VA_ARGS__)

	#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)

	int __i915_inject_probe_error(struct drm_i915_private *i915, int err,
	const char *func, int line);
	#define i915_inject_probe_error(_i915, _err) \
	__i915_inject_probe_error((_i915), (_err), __func__, __LINE__)
	bool i915_error_injected(void);

	#else

	#define i915_inject_probe_error(i915, e) ({ BUILD_BUG_ON_INVALID(i915); 0; })
	#define i915_error_injected() false

	#endif

	#define i915_inject_probe_failure(i915) i915_inject_probe_error((i915), -ENODEV)

	#define i915_probe_error(i915, fmt, ...) \
	__i915_printk(i915, i915_error_injected() ? KERN_DEBUG : KERN_ERR, \
	fmt, ##__VA_ARGS__)

	#if defined(GCC_VERSION) && GCC_VERSION >= 70000
	#define add_overflows_t(T, A, B) \
	__builtin_add_overflow_p((A), (B), (T)0)
	#else
	#define add_overflows_t(T, A, B) ({ \
	typeof(A) a = (A); \
	typeof(B) b = (B); \
	(T)(a + b) < a; \
	})
	#endif

	#define add_overflows(A, B) \
	add_overflows_t(typeof((A) + (B)), (A), (B))

	#define range_overflows(start, size, max) ({ \
	typeof(start) start__ = (start); \
	typeof(size) size__ = (size); \
	typeof(max) max__ = (max); \
	(void)(&start__ == &size__); \
	(void)(&start__ == &max__); \
	start__ > max__ \|\| size__ > max__ - start__; \
	})

	#define range_overflows_t(type, start, size, max) \
	range_overflows((type)(start), (type)(size), (type)(max))

	/* Note we don't consider signbits :\| */
	#define overflows_type(x, T) \
	(sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T))

	static inline bool
	__check_struct_size(size_t base, size_t arr, size_t count, size_t *size)
	{
	size_t sz;

	if (check_mul_overflow(count, arr, &sz))
	return false;

	if (check_add_overflow(sz, base, &sz))
	return false;

	*size = sz;
	return true;
	}

	/**
	* check_struct_size() - Calculate size of structure with trailing array.
	* @p: Pointer to the structure.
	* @member: Name of the array member.
	* @n: Number of elements in the array.
	* @sz: Total size of structure and array
	*
	* Calculates size of memory needed for structure @p followed by an
	* array of @n @member elements, like struct_size() but reports
	* whether it overflowed, and the resultant size in @sz
	*
	* Return: false if the calculation overflowed.
	*/
	#define check_struct_size(p, member, n, sz) \
	likely(__check_struct_size(sizeof(*(p)), \
	sizeof(*(p)->member) + __must_be_array((p)->member), \
	n, sz))

	#define ptr_mask_bits(ptr, n) ({ \
	unsigned long __v = (unsigned long)(ptr); \
	(typeof(ptr))(__v & -BIT(n)); \
	})

	#define ptr_unmask_bits(ptr, n) ((unsigned long)(ptr) & (BIT(n) - 1))

	#define ptr_unpack_bits(ptr, bits, n) ({ \
	unsigned long __v = (unsigned long)(ptr); \
	*(bits) = __v & (BIT(n) - 1); \
	(typeof(ptr))(__v & -BIT(n)); \
	})

	#define ptr_pack_bits(ptr, bits, n) ({ \
	unsigned long __bits = (bits); \
	GEM_BUG_ON(__bits & -BIT(n)); \
	((typeof(ptr))((unsigned long)(ptr) \| __bits)); \
	})

	#define ptr_dec(ptr) ({ \
	unsigned long __v = (unsigned long)(ptr); \
	(typeof(ptr))(__v - 1); \
	})

	#define ptr_inc(ptr) ({ \
	unsigned long __v = (unsigned long)(ptr); \
	(typeof(ptr))(__v + 1); \
	})

	#define page_mask_bits(ptr) ptr_mask_bits(ptr, PAGE_SHIFT)
	#define page_unmask_bits(ptr) ptr_unmask_bits(ptr, PAGE_SHIFT)
	#define page_pack_bits(ptr, bits) ptr_pack_bits(ptr, bits, PAGE_SHIFT)
	#define page_unpack_bits(ptr, bits) ptr_unpack_bits(ptr, bits, PAGE_SHIFT)

	#define struct_member(T, member) (((T *)0)->member)

	#define ptr_offset(ptr, member) offsetof(typeof(*(ptr)), member)

	#define fetch_and_zero(ptr) ({ \
	typeof(ptr) __T = (ptr); \
	(ptr) = (typeof(ptr))0; \
	__T; \
	})

	/*
	* container_of_user: Extract the superclass from a pointer to a member.
	*
	* Exactly like container_of() with the exception that it plays nicely
	* with sparse for __user @ptr.
	*/
	#define container_of_user(ptr, type, member) ({ \
	void __user __mptr = (void __user )(ptr); \
	BUILD_BUG_ON_MSG(!__same_type(*(ptr), struct_member(type, member)) && \
	!__same_type(*(ptr), void), \
	"pointer type mismatch in container_of()"); \
	((type __user *)(__mptr - offsetof(type, member))); })

	/*
	* check_user_mbz: Check that a user value exists and is zero
	*
	* Frequently in our uABI we reserve space for future extensions, and
	* two ensure that userspace is prepared we enforce that space must
	* be zero. (Then any future extension can safely assume a default value
	* of 0.)
	*
	* check_user_mbz() combines checking that the user pointer is accessible
	* and that the contained value is zero.
	*
	* Returns: -EFAULT if not accessible, -EINVAL if !zero, or 0 on success.
	*/
	#define check_user_mbz(U) ({ \
	typeof(*(U)) mbz__; \
	get_user(mbz__, (U)) ? -EFAULT : mbz__ ? -EINVAL : 0; \
	})

	static inline u64 ptr_to_u64(const void *ptr)
	{
	return (uintptr_t)ptr;
	}

	#define u64_to_ptr(T, x) ({ \
	typecheck(u64, x); \
	(T *)(uintptr_t)(x); \
	})

	#define __mask_next_bit(mask) ({ \
	int __idx = ffs(mask) - 1; \
	mask &= ~BIT(__idx); \
	__idx; \
	})

	static inline bool is_power_of_2_u64(u64 n)
	{
	return (n != 0 && ((n & (n - 1)) == 0));
	}

	static inline void __list_del_many(struct list_head *head,
	struct list_head *first)
	{
	first->prev = head;
	WRITE_ONCE(head->next, first);
	}

	/*
	* Wait until the work is finally complete, even if it tries to postpone
	* by requeueing itself. Note, that if the worker never cancels itself,
	* we will spin forever.
	*/
	static inline void drain_delayed_work(struct delayed_work *dw)
	{
	do {
	while (flush_delayed_work(dw))
	;
	} while (delayed_work_pending(dw));
	}

	static inline unsigned long msecs_to_jiffies_timeout(const unsigned int m)
	{
	unsigned long j = msecs_to_jiffies(m);

	return min_t(unsigned long, MAX_JIFFY_OFFSET, j + 1);
	}

	/*
	* If you need to wait X milliseconds between events A and B, but event B
	* doesn't happen exactly after event A, you record the timestamp (jiffies) of
	* when event A happened, then just before event B you call this function and
	* pass the timestamp as the first argument, and X as the second argument.
	*/
	static inline void
	wait_remaining_ms_from_jiffies(unsigned long timestamp_jiffies, int to_wait_ms)
	{
	unsigned long target_jiffies, tmp_jiffies, remaining_jiffies;

	/*
	* Don't re-read the value of "jiffies" every time since it may change
	* behind our back and break the math.
	*/
	tmp_jiffies = jiffies;
	target_jiffies = timestamp_jiffies +
	msecs_to_jiffies_timeout(to_wait_ms);

	if (time_after(target_jiffies, tmp_jiffies)) {
	remaining_jiffies = target_jiffies - tmp_jiffies;
	while (remaining_jiffies)
	remaining_jiffies =
	schedule_timeout_uninterruptible(remaining_jiffies);
	}
	}

	/**
	* __wait_for - magic wait macro
	*
	* Macro to help avoid open coding check/wait/timeout patterns. Note that it's
	* important that we check the condition again after having timed out, since the
	* timeout could be due to preemption or similar and we've never had a chance to
	* check the condition before the timeout.
	*/
	#define __wait_for(OP, COND, US, Wmin, Wmax) ({ \
	const ktime_t end__ = ktime_add_ns(ktime_get_raw(), 1000ll * (US)); \
	long wait__ = (Wmin); /* recommended min for usleep is 10 us */ \
	int ret__; \
	might_sleep(); \
	for (;;) { \
	const bool expired__ = ktime_after(ktime_get_raw(), end__); \
	OP; \
	/* Guarantee COND check prior to timeout */ \
	barrier(); \
	if (COND) { \
	ret__ = 0; \
	break; \
	} \
	if (expired__) { \
	ret__ = -ETIMEDOUT; \
	break; \
	} \
	usleep_range(wait__, wait__ * 2); \
	if (wait__ < (Wmax)) \
	wait__ <<= 1; \
	} \
	ret__; \
	})

	#define _wait_for(COND, US, Wmin, Wmax) __wait_for(, (COND), (US), (Wmin), \
	(Wmax))
	#define wait_for(COND, MS) _wait_for((COND), (MS) * 1000, 10, 1000)

	/* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */
	#if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT)
	# define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) WARN_ON_ONCE((ATOMIC) && !in_atomic())
	#else
	# define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) do { } while (0)
	#endif

	#define _wait_for_atomic(COND, US, ATOMIC) \
	({ \
	int cpu, ret, timeout = (US) * 1000; \
	u64 base; \
	_WAIT_FOR_ATOMIC_CHECK(ATOMIC); \
	if (!(ATOMIC)) { \
	preempt_disable(); \
	cpu = smp_processor_id(); \
	} \
	base = local_clock(); \
	for (;;) { \
	u64 now = local_clock(); \
	if (!(ATOMIC)) \
	preempt_enable(); \
	/* Guarantee COND check prior to timeout */ \
	barrier(); \
	if (COND) { \
	ret = 0; \
	break; \
	} \
	if (now - base >= timeout) { \
	ret = -ETIMEDOUT; \
	break; \
	} \
	cpu_relax(); \
	if (!(ATOMIC)) { \
	preempt_disable(); \
	if (unlikely(cpu != smp_processor_id())) { \
	timeout -= now - base; \
	cpu = smp_processor_id(); \
	base = local_clock(); \
	} \
	} \
	} \
	ret; \
	})

	#define wait_for_us(COND, US) \
	({ \
	int ret__; \
	BUILD_BUG_ON(!__builtin_constant_p(US)); \
	if ((US) > 10) \
	ret__ = _wait_for((COND), (US), 10, 10); \
	else \
	ret__ = _wait_for_atomic((COND), (US), 0); \
	ret__; \
	})

	#define wait_for_atomic_us(COND, US) \
	({ \
	BUILD_BUG_ON(!__builtin_constant_p(US)); \
	BUILD_BUG_ON((US) > 50000); \
	_wait_for_atomic((COND), (US), 1); \
	})

	#define wait_for_atomic(COND, MS) wait_for_atomic_us((COND), (MS) * 1000)

	#define KHz(x) (1000 * (x))
	#define MHz(x) KHz(1000 * (x))

	#define KBps(x) (1000 * (x))
	#define MBps(x) KBps(1000 * (x))
	#define GBps(x) ((u64)1000 * MBps((x)))

	static inline const char *yesno(bool v)
	{
	return v ? "yes" : "no";
	}

	static inline const char *onoff(bool v)
	{
	return v ? "on" : "off";
	}

	static inline const char *enableddisabled(bool v)
	{
	return v ? "enabled" : "disabled";
	}

	static inline void add_taint_for_CI(unsigned int taint)
	{
	/*
	* The system is "ok", just about surviving for the user, but
	* CI results are now unreliable as the HW is very suspect.
	* CI checks the taint state after every test and will reboot
	* the machine if the kernel is tainted.
	*/
	add_taint(taint, LOCKDEP_STILL_OK);
	}

	void cancel_timer(struct timer_list *t);
	void set_timer_ms(struct timer_list *t, unsigned long timeout);

	static inline bool timer_expired(const struct timer_list *t)
	{
	return READ_ONCE(t->expires) && !timer_pending(t);
	}

	/*
	* This is a lookalike for IS_ENABLED() that takes a kconfig value,
	* e.g. CONFIG_DRM_I915_SPIN_REQUEST, and evaluates whether it is non-zero
	* i.e. whether the configuration is active. Wrapping up the config inside
	* a boolean context prevents clang and smatch from complaining about potential
	* issues in confusing logical-&& with bitwise-& for constants.
	*
	* Sadly IS_ENABLED() itself does not work with kconfig values.
	*
	* Returns 0 if @config is 0, 1 if set to any value.
	*/
	#define IS_ACTIVE(config) ((config) != 0)

	#endif /* !__I915_UTILS_H */