Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "The main changes in this cycle were:

   - A comprehensive rewrite of the robust/PI futex code's exit handling
     to fix various exit races. (Thomas Gleixner et al)

   - Rework the generic REFCOUNT_FULL implementation using
     atomic_fetch_* operations so that the performance impact of the
     cmpxchg() loops is mitigated for common refcount operations.

     With these performance improvements the generic implementation of
     refcount_t should be good enough for everybody - and this got
     confirmed by performance testing, so remove ARCH_HAS_REFCOUNT and
     REFCOUNT_FULL entirely, leaving the generic implementation enabled
     unconditionally. (Will Deacon)

   - Other misc changes, fixes, cleanups"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
  lkdtm: Remove references to CONFIG_REFCOUNT_FULL
  locking/refcount: Remove unused 'refcount_error_report()' function
  locking/refcount: Consolidate implementations of refcount_t
  locking/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions
  locking/refcount: Move saturation warnings out of line
  locking/refcount: Improve performance of generic REFCOUNT_FULL code
  locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the <linux/refcount.h> header
  locking/refcount: Remove unused refcount_*_checked() variants
  locking/refcount: Ensure integer operands are treated as signed
  locking/refcount: Define constants for saturation and max refcount values
  futex: Prevent exit livelock
  futex: Provide distinct return value when owner is exiting
  futex: Add mutex around futex exit
  futex: Provide state handling for exec() as well
  futex: Sanitize exit state handling
  futex: Mark the begin of futex exit explicitly
  futex: Set task::futex_state to DEAD right after handling futex exit
  futex: Split futex_mm_release() for exit/exec
  exit/exec: Seperate mm_release()
  futex: Replace PF_EXITPIDONE with a state
  ...

3 files changed, 40 insertions, 241 deletions

diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index a1705545e6ac..14f44f59e733 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -1475,7 +1475,7 @@ static void ww_test_edeadlk_normal(void)
 
 	mutex_lock(&o2.base);
 	o2.ctx = &t2;
-	mutex_release(&o2.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o2.base.dep_map, _THIS_IP_);
 
 	WWAI(&t);
 	t2 = t;
@@ -1500,7 +1500,7 @@ static void ww_test_edeadlk_normal_slow(void)
 	int ret;
 
 	mutex_lock(&o2.base);
-	mutex_release(&o2.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o2.base.dep_map, _THIS_IP_);
 	o2.ctx = &t2;
 
 	WWAI(&t);
@@ -1527,7 +1527,7 @@ static void ww_test_edeadlk_no_unlock(void)
 
 	mutex_lock(&o2.base);
 	o2.ctx = &t2;
-	mutex_release(&o2.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o2.base.dep_map, _THIS_IP_);
 
 	WWAI(&t);
 	t2 = t;
@@ -1551,7 +1551,7 @@ static void ww_test_edeadlk_no_unlock_slow(void)
 	int ret;
 
 	mutex_lock(&o2.base);
-	mutex_release(&o2.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o2.base.dep_map, _THIS_IP_);
 	o2.ctx = &t2;
 
 	WWAI(&t);
@@ -1576,7 +1576,7 @@ static void ww_test_edeadlk_acquire_more(void)
 	int ret;
 
 	mutex_lock(&o2.base);
-	mutex_release(&o2.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o2.base.dep_map, _THIS_IP_);
 	o2.ctx = &t2;
 
 	WWAI(&t);
@@ -1597,7 +1597,7 @@ static void ww_test_edeadlk_acquire_more_slow(void)
 	int ret;
 
 	mutex_lock(&o2.base);
-	mutex_release(&o2.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o2.base.dep_map, _THIS_IP_);
 	o2.ctx = &t2;
 
 	WWAI(&t);
@@ -1618,11 +1618,11 @@ static void ww_test_edeadlk_acquire_more_edeadlk(void)
 	int ret;
 
 	mutex_lock(&o2.base);
-	mutex_release(&o2.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o2.base.dep_map, _THIS_IP_);
 	o2.ctx = &t2;
 
 	mutex_lock(&o3.base);
-	mutex_release(&o3.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o3.base.dep_map, _THIS_IP_);
 	o3.ctx = &t2;
 
 	WWAI(&t);
@@ -1644,11 +1644,11 @@ static void ww_test_edeadlk_acquire_more_edeadlk_slow(void)
 	int ret;
 
 	mutex_lock(&o2.base);
-	mutex_release(&o2.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o2.base.dep_map, _THIS_IP_);
 	o2.ctx = &t2;
 
 	mutex_lock(&o3.base);
-	mutex_release(&o3.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o3.base.dep_map, _THIS_IP_);
 	o3.ctx = &t2;
 
 	WWAI(&t);
@@ -1669,7 +1669,7 @@ static void ww_test_edeadlk_acquire_wrong(void)
 	int ret;
 
 	mutex_lock(&o2.base);
-	mutex_release(&o2.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o2.base.dep_map, _THIS_IP_);
 	o2.ctx = &t2;
 
 	WWAI(&t);
@@ -1694,7 +1694,7 @@ static void ww_test_edeadlk_acquire_wrong_slow(void)
 	int ret;
 
 	mutex_lock(&o2.base);
-	mutex_release(&o2.base.dep_map, 1, _THIS_IP_);
+	mutex_release(&o2.base.dep_map, _THIS_IP_);
 	o2.ctx = &t2;
 
 	WWAI(&t);
diff --git a/lib/refcount.c b/lib/refcount.c
index 6e904af0fb3e..ebac8b7d15a7 100644
--- a/lib/refcount.c
+++ b/lib/refcount.c
@@ -1,41 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * Variant of atomic_t specialized for reference counts.
- *
- * The interface matches the atomic_t interface (to aid in porting) but only
- * provides the few functions one should use for reference counting.
- *
- * It differs in that the counter saturates at UINT_MAX and will not move once
- * there. This avoids wrapping the counter and causing 'spurious'
- * use-after-free issues.
- *
- * Memory ordering rules are slightly relaxed wrt regular atomic_t functions
- * and provide only what is strictly required for refcounts.
- *
- * The increments are fully relaxed; these will not provide ordering. The
- * rationale is that whatever is used to obtain the object we're increasing the
- * reference count on will provide the ordering. For locked data structures,
- * its the lock acquire, for RCU/lockless data structures its the dependent
- * load.
- *
- * Do note that inc_not_zero() provides a control dependency which will order
- * future stores against the inc, this ensures we'll never modify the object
- * if we did not in fact acquire a reference.
- *
- * The decrements will provide release order, such that all the prior loads and
- * stores will be issued before, it also provides a control dependency, which
- * will order us against the subsequent free().
- *
- * The control dependency is against the load of the cmpxchg (ll/sc) that
- * succeeded. This means the stores aren't fully ordered, but this is fine
- * because the 1->0 transition indicates no concurrency.
- *
- * Note that the allocator is responsible for ordering things between free()
- * and alloc().
- *
- * The decrements dec_and_test() and sub_and_test() also provide acquire
- * ordering on success.
- *
+ * Out-of-line refcount functions.
  */
 
 #include <linux/mutex.h>
@@ -43,199 +8,33 @@
 #include <linux/spinlock.h>
 #include <linux/bug.h>
 
-/**
- * refcount_add_not_zero_checked - add a value to a refcount unless it is 0
- * @i: the value to add to the refcount
- * @r: the refcount
- *
- * Will saturate at UINT_MAX and WARN.
- *
- * Provides no memory ordering, it is assumed the caller has guaranteed the
- * object memory to be stable (RCU, etc.). It does provide a control dependency
- * and thereby orders future stores. See the comment on top.
- *
- * Use of this function is not recommended for the normal reference counting
- * use case in which references are taken and released one at a time.  In these
- * cases, refcount_inc(), or one of its variants, should instead be used to
- * increment a reference count.
- *
- * Return: false if the passed refcount is 0, true otherwise
- */
-bool refcount_add_not_zero_checked(unsigned int i, refcount_t *r)
-{
-	unsigned int new, val = atomic_read(&r->refs);
-
-	do {
-		if (!val)
-			return false;
-
-		if (unlikely(val == UINT_MAX))
-			return true;
-
-		new = val + i;
-		if (new < val)
-			new = UINT_MAX;
-
-	} while (!atomic_try_cmpxchg_relaxed(&r->refs, &val, new));
-
-	WARN_ONCE(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n");
-
-	return true;
-}
-EXPORT_SYMBOL(refcount_add_not_zero_checked);
-
-/**
- * refcount_add_checked - add a value to a refcount
- * @i: the value to add to the refcount
- * @r: the refcount
- *
- * Similar to atomic_add(), but will saturate at UINT_MAX and WARN.
- *
- * Provides no memory ordering, it is assumed the caller has guaranteed the
- * object memory to be stable (RCU, etc.). It does provide a control dependency
- * and thereby orders future stores. See the comment on top.
- *
- * Use of this function is not recommended for the normal reference counting
- * use case in which references are taken and released one at a time.  In these
- * cases, refcount_inc(), or one of its variants, should instead be used to
- * increment a reference count.
- */
-void refcount_add_checked(unsigned int i, refcount_t *r)
-{
-	WARN_ONCE(!refcount_add_not_zero_checked(i, r), "refcount_t: addition on 0; use-after-free.\n");
-}
-EXPORT_SYMBOL(refcount_add_checked);
-
-/**
- * refcount_inc_not_zero_checked - increment a refcount unless it is 0
- * @r: the refcount to increment
- *
- * Similar to atomic_inc_not_zero(), but will saturate at UINT_MAX and WARN.
- *
- * Provides no memory ordering, it is assumed the caller has guaranteed the
- * object memory to be stable (RCU, etc.). It does provide a control dependency
- * and thereby orders future stores. See the comment on top.
- *
- * Return: true if the increment was successful, false otherwise
- */
-bool refcount_inc_not_zero_checked(refcount_t *r)
-{
-	unsigned int new, val = atomic_read(&r->refs);
-
-	do {
-		new = val + 1;
-
-		if (!val)
-			return false;
-
-		if (unlikely(!new))
-			return true;
-
-	} while (!atomic_try_cmpxchg_relaxed(&r->refs, &val, new));
+#define REFCOUNT_WARN(str)	WARN_ONCE(1, "refcount_t: " str ".\n")
 
-	WARN_ONCE(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n");
-
-	return true;
-}
-EXPORT_SYMBOL(refcount_inc_not_zero_checked);
-
-/**
- * refcount_inc_checked - increment a refcount
- * @r: the refcount to increment
- *
- * Similar to atomic_inc(), but will saturate at UINT_MAX and WARN.
- *
- * Provides no memory ordering, it is assumed the caller already has a
- * reference on the object.
- *
- * Will WARN if the refcount is 0, as this represents a possible use-after-free
- * condition.
- */
-void refcount_inc_checked(refcount_t *r)
+void refcount_warn_saturate(refcount_t *r, enum refcount_saturation_type t)
 {
-	WARN_ONCE(!refcount_inc_not_zero_checked(r), "refcount_t: increment on 0; use-after-free.\n");
-}
-EXPORT_SYMBOL(refcount_inc_checked);
-
-/**
- * refcount_sub_and_test_checked - subtract from a refcount and test if it is 0
- * @i: amount to subtract from the refcount
- * @r: the refcount
- *
- * Similar to atomic_dec_and_test(), but it will WARN, return false and
- * ultimately leak on underflow and will fail to decrement when saturated
- * at UINT_MAX.
- *
- * Provides release memory ordering, such that prior loads and stores are done
- * before, and provides an acquire ordering on success such that free()
- * must come after.
- *
- * Use of this function is not recommended for the normal reference counting
- * use case in which references are taken and released one at a time.  In these
- * cases, refcount_dec(), or one of its variants, should instead be used to
- * decrement a reference count.
- *
- * Return: true if the resulting refcount is 0, false otherwise
- */
-bool refcount_sub_and_test_checked(unsigned int i, refcount_t *r)
-{
-	unsigned int new, val = atomic_read(&r->refs);
-
-	do {
-		if (unlikely(val == UINT_MAX))
-			return false;
-
-		new = val - i;
-		if (new > val) {
-			WARN_ONCE(new > val, "refcount_t: underflow; use-after-free.\n");
-			return false;
-		}
-
-	} while (!atomic_try_cmpxchg_release(&r->refs, &val, new));
-
-	if (!new) {
-		smp_acquire__after_ctrl_dep();
-		return true;
+	refcount_set(r, REFCOUNT_SATURATED);
+
+	switch (t) {
+	case REFCOUNT_ADD_NOT_ZERO_OVF:
+		REFCOUNT_WARN("saturated; leaking memory");
+		break;
+	case REFCOUNT_ADD_OVF:
+		REFCOUNT_WARN("saturated; leaking memory");
+		break;
+	case REFCOUNT_ADD_UAF:
+		REFCOUNT_WARN("addition on 0; use-after-free");
+		break;
+	case REFCOUNT_SUB_UAF:
+		REFCOUNT_WARN("underflow; use-after-free");
+		break;
+	case REFCOUNT_DEC_LEAK:
+		REFCOUNT_WARN("decrement hit 0; leaking memory");
+		break;
+	default:
+		REFCOUNT_WARN("unknown saturation event!?");
 	}
-	return false;
-
-}
-EXPORT_SYMBOL(refcount_sub_and_test_checked);
-
-/**
- * refcount_dec_and_test_checked - decrement a refcount and test if it is 0
- * @r: the refcount
- *
- * Similar to atomic_dec_and_test(), it will WARN on underflow and fail to
- * decrement when saturated at UINT_MAX.
- *
- * Provides release memory ordering, such that prior loads and stores are done
- * before, and provides an acquire ordering on success such that free()
- * must come after.
- *
- * Return: true if the resulting refcount is 0, false otherwise
- */
-bool refcount_dec_and_test_checked(refcount_t *r)
-{
-	return refcount_sub_and_test_checked(1, r);
-}
-EXPORT_SYMBOL(refcount_dec_and_test_checked);
-
-/**
- * refcount_dec_checked - decrement a refcount
- * @r: the refcount
- *
- * Similar to atomic_dec(), it will WARN on underflow and fail to decrement
- * when saturated at UINT_MAX.
- *
- * Provides release memory ordering, such that prior loads and stores are done
- * before.
- */
-void refcount_dec_checked(refcount_t *r)
-{
-	WARN_ONCE(refcount_dec_and_test_checked(r), "refcount_t: decrement hit 0; leaking memory.\n");
 }
-EXPORT_SYMBOL(refcount_dec_checked);
+EXPORT_SYMBOL(refcount_warn_saturate);
 
 /**
  * refcount_dec_if_one - decrement a refcount if it is 1
@@ -277,7 +76,7 @@ bool refcount_dec_not_one(refcount_t *r)
 	unsigned int new, val = atomic_read(&r->refs);
 
 	do {
-		if (unlikely(val == UINT_MAX))
+		if (unlikely(val == REFCOUNT_SATURATED))
 			return true;
 
 		if (val == 1)
@@ -302,7 +101,7 @@ EXPORT_SYMBOL(refcount_dec_not_one);
  * @lock: the mutex to be locked
  *
  * Similar to atomic_dec_and_mutex_lock(), it will WARN on underflow and fail
- * to decrement when saturated at UINT_MAX.
+ * to decrement when saturated at REFCOUNT_SATURATED.
  *
  * Provides release memory ordering, such that prior loads and stores are done
  * before, and provides a control dependency such that free() must come after.
@@ -333,7 +132,7 @@ EXPORT_SYMBOL(refcount_dec_and_mutex_lock);
  * @lock: the spinlock to be locked
  *
  * Similar to atomic_dec_and_lock(), it will WARN on underflow and fail to
- * decrement when saturated at UINT_MAX.
+ * decrement when saturated at REFCOUNT_SATURATED.
  *
  * Provides release memory ordering, such that prior loads and stores are done
  * before, and provides a control dependency such that free() must come after.
diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
index 60ba93fc42ce..bd9571653288 100644
--- a/lib/smp_processor_id.c
+++ b/lib/smp_processor_id.c
@@ -23,7 +23,7 @@ unsigned int check_preemption_disabled(const char *what1, const char *what2)
 	 * Kernel threads bound to a single CPU can safely use
 	 * smp_processor_id():
 	 */
-	if (cpumask_equal(current->cpus_ptr, cpumask_of(this_cpu)))
+	if (current->nr_cpus_allowed == 1)
 		goto out;
 
 	/*