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-rw-r--r--kernel/locking/Makefile1
-rw-r--r--kernel/locking/lockdep.c635
-rw-r--r--kernel/locking/lockdep_internals.h1
-rw-r--r--kernel/locking/lockdep_proc.c1
-rw-r--r--kernel/locking/mcs_spinlock.h1
-rw-r--r--kernel/locking/mutex-debug.h1
-rw-r--r--kernel/locking/mutex.h1
-rw-r--r--kernel/locking/osq_lock.c1
-rw-r--r--kernel/locking/qrwlock.c86
-rw-r--r--kernel/locking/qspinlock_paravirt.h48
-rw-r--r--kernel/locking/rtmutex-debug.c1
-rw-r--r--kernel/locking/rtmutex-debug.h1
-rw-r--r--kernel/locking/rtmutex.h1
-rw-r--r--kernel/locking/rtmutex_common.h1
-rw-r--r--kernel/locking/rwsem-spinlock.c1
-rw-r--r--kernel/locking/rwsem-xadd.c1
-rw-r--r--kernel/locking/rwsem.c17
-rw-r--r--kernel/locking/rwsem.h1
-rw-r--r--kernel/locking/spinlock.c19
19 files changed, 125 insertions, 694 deletions
diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index 760158d9d98d..392c7f23af76 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
# Any varying coverage in these files is non-deterministic
# and is generally not a function of system call inputs.
KCOV_INSTRUMENT := n
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index e36e652d996f..5fa1324a4f29 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -47,7 +47,6 @@
#include <linux/stringify.h>
#include <linux/bitops.h>
#include <linux/gfp.h>
-#include <linux/kmemcheck.h>
#include <linux/random.h>
#include <linux/jhash.h>
@@ -58,10 +57,6 @@
#define CREATE_TRACE_POINTS
#include <trace/events/lock.h>
-#ifdef CONFIG_LOCKDEP_CROSSRELEASE
-#include <linux/slab.h>
-#endif
-
#ifdef CONFIG_PROVE_LOCKING
int prove_locking = 1;
module_param(prove_locking, int, 0644);
@@ -728,18 +723,6 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
return is_static || static_obj(lock->key) ? NULL : ERR_PTR(-EINVAL);
}
-#ifdef CONFIG_LOCKDEP_CROSSRELEASE
-static void cross_init(struct lockdep_map *lock, int cross);
-static int cross_lock(struct lockdep_map *lock);
-static int lock_acquire_crosslock(struct held_lock *hlock);
-static int lock_release_crosslock(struct lockdep_map *lock);
-#else
-static inline void cross_init(struct lockdep_map *lock, int cross) {}
-static inline int cross_lock(struct lockdep_map *lock) { return 0; }
-static inline int lock_acquire_crosslock(struct held_lock *hlock) { return 2; }
-static inline int lock_release_crosslock(struct lockdep_map *lock) { return 2; }
-#endif
-
/*
* Register a lock's class in the hash-table, if the class is not present
* yet. Otherwise we look it up. We cache the result in the lock object
@@ -1139,41 +1122,22 @@ print_circular_lock_scenario(struct held_lock *src,
printk(KERN_CONT "\n\n");
}
- if (cross_lock(tgt->instance)) {
- printk(" Possible unsafe locking scenario by crosslock:\n\n");
- printk(" CPU0 CPU1\n");
- printk(" ---- ----\n");
- printk(" lock(");
- __print_lock_name(parent);
- printk(KERN_CONT ");\n");
- printk(" lock(");
- __print_lock_name(target);
- printk(KERN_CONT ");\n");
- printk(" lock(");
- __print_lock_name(source);
- printk(KERN_CONT ");\n");
- printk(" unlock(");
- __print_lock_name(target);
- printk(KERN_CONT ");\n");
- printk("\n *** DEADLOCK ***\n\n");
- } else {
- printk(" Possible unsafe locking scenario:\n\n");
- printk(" CPU0 CPU1\n");
- printk(" ---- ----\n");
- printk(" lock(");
- __print_lock_name(target);
- printk(KERN_CONT ");\n");
- printk(" lock(");
- __print_lock_name(parent);
- printk(KERN_CONT ");\n");
- printk(" lock(");
- __print_lock_name(target);
- printk(KERN_CONT ");\n");
- printk(" lock(");
- __print_lock_name(source);
- printk(KERN_CONT ");\n");
- printk("\n *** DEADLOCK ***\n\n");
- }
+ printk(" Possible unsafe locking scenario:\n\n");
+ printk(" CPU0 CPU1\n");
+ printk(" ---- ----\n");
+ printk(" lock(");
+ __print_lock_name(target);
+ printk(KERN_CONT ");\n");
+ printk(" lock(");
+ __print_lock_name(parent);
+ printk(KERN_CONT ");\n");
+ printk(" lock(");
+ __print_lock_name(target);
+ printk(KERN_CONT ");\n");
+ printk(" lock(");
+ __print_lock_name(source);
+ printk(KERN_CONT ");\n");
+ printk("\n *** DEADLOCK ***\n\n");
}
/*
@@ -1199,10 +1163,7 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth,
curr->comm, task_pid_nr(curr));
print_lock(check_src);
- if (cross_lock(check_tgt->instance))
- pr_warn("\nbut now in release context of a crosslock acquired at the following:\n");
- else
- pr_warn("\nbut task is already holding lock:\n");
+ pr_warn("\nbut task is already holding lock:\n");
print_lock(check_tgt);
pr_warn("\nwhich lock already depends on the new lock.\n\n");
@@ -1232,9 +1193,7 @@ static noinline int print_circular_bug(struct lock_list *this,
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
- if (cross_lock(check_tgt->instance))
- this->trace = *trace;
- else if (!save_trace(&this->trace))
+ if (!save_trace(&this->trace))
return 0;
depth = get_lock_depth(target);
@@ -1838,9 +1797,6 @@ check_deadlock(struct task_struct *curr, struct held_lock *next,
if (nest)
return 2;
- if (cross_lock(prev->instance))
- continue;
-
return print_deadlock_bug(curr, prev, next);
}
return 1;
@@ -2006,31 +1962,26 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
for (;;) {
int distance = curr->lockdep_depth - depth + 1;
hlock = curr->held_locks + depth - 1;
+
/*
- * Only non-crosslock entries get new dependencies added.
- * Crosslock entries will be added by commit later:
+ * Only non-recursive-read entries get new dependencies
+ * added:
*/
- if (!cross_lock(hlock->instance)) {
+ if (hlock->read != 2 && hlock->check) {
+ int ret = check_prev_add(curr, hlock, next, distance, &trace, save_trace);
+ if (!ret)
+ return 0;
+
/*
- * Only non-recursive-read entries get new dependencies
- * added:
+ * Stop after the first non-trylock entry,
+ * as non-trylock entries have added their
+ * own direct dependencies already, so this
+ * lock is connected to them indirectly:
*/
- if (hlock->read != 2 && hlock->check) {
- int ret = check_prev_add(curr, hlock, next,
- distance, &trace, save_trace);
- if (!ret)
- return 0;
-
- /*
- * Stop after the first non-trylock entry,
- * as non-trylock entries have added their
- * own direct dependencies already, so this
- * lock is connected to them indirectly:
- */
- if (!hlock->trylock)
- break;
- }
+ if (!hlock->trylock)
+ break;
}
+
depth--;
/*
* End of lock-stack?
@@ -3225,8 +3176,6 @@ static void __lockdep_init_map(struct lockdep_map *lock, const char *name,
{
int i;
- kmemcheck_mark_initialized(lock, sizeof(*lock));
-
for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
lock->class_cache[i] = NULL;
@@ -3282,21 +3231,10 @@ static void __lockdep_init_map(struct lockdep_map *lock, const char *name,
void lockdep_init_map(struct lockdep_map *lock, const char *name,
struct lock_class_key *key, int subclass)
{
- cross_init(lock, 0);
__lockdep_init_map(lock, name, key, subclass);
}
EXPORT_SYMBOL_GPL(lockdep_init_map);
-#ifdef CONFIG_LOCKDEP_CROSSRELEASE
-void lockdep_init_map_crosslock(struct lockdep_map *lock, const char *name,
- struct lock_class_key *key, int subclass)
-{
- cross_init(lock, 1);
- __lockdep_init_map(lock, name, key, subclass);
-}
-EXPORT_SYMBOL_GPL(lockdep_init_map_crosslock);
-#endif
-
struct lock_class_key __lockdep_no_validate__;
EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
@@ -3352,7 +3290,6 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
int chain_head = 0;
int class_idx;
u64 chain_key;
- int ret;
if (unlikely(!debug_locks))
return 0;
@@ -3401,8 +3338,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
class_idx = class - lock_classes + 1;
- /* TODO: nest_lock is not implemented for crosslock yet. */
- if (depth && !cross_lock(lock)) {
+ if (depth) {
hlock = curr->held_locks + depth - 1;
if (hlock->class_idx == class_idx && nest_lock) {
if (hlock->references) {
@@ -3490,14 +3426,6 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
return 0;
- ret = lock_acquire_crosslock(hlock);
- /*
- * 2 means normal acquire operations are needed. Otherwise, it's
- * ok just to return with '0:fail, 1:success'.
- */
- if (ret != 2)
- return ret;
-
curr->curr_chain_key = chain_key;
curr->lockdep_depth++;
check_chain_key(curr);
@@ -3735,19 +3663,11 @@ __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
struct task_struct *curr = current;
struct held_lock *hlock;
unsigned int depth;
- int ret, i;
+ int i;
if (unlikely(!debug_locks))
return 0;
- ret = lock_release_crosslock(lock);
- /*
- * 2 means normal release operations are needed. Otherwise, it's
- * ok just to return with '0:fail, 1:success'.
- */
- if (ret != 2)
- return ret;
-
depth = curr->lockdep_depth;
/*
* So we're all set to release this lock.. wait what lock? We don't
@@ -4665,488 +4585,3 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
dump_stack();
}
EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
-
-#ifdef CONFIG_LOCKDEP_CROSSRELEASE
-
-/*
- * Crossrelease works by recording a lock history for each thread and
- * connecting those historic locks that were taken after the
- * wait_for_completion() in the complete() context.
- *
- * Task-A Task-B
- *
- * mutex_lock(&A);
- * mutex_unlock(&A);
- *
- * wait_for_completion(&C);
- * lock_acquire_crosslock();
- * atomic_inc_return(&cross_gen_id);
- * |
- * | mutex_lock(&B);
- * | mutex_unlock(&B);
- * |
- * | complete(&C);
- * `-- lock_commit_crosslock();
- *
- * Which will then add a dependency between B and C.
- */
-
-#define xhlock(i) (current->xhlocks[(i) % MAX_XHLOCKS_NR])
-
-/*
- * Whenever a crosslock is held, cross_gen_id will be increased.
- */
-static atomic_t cross_gen_id; /* Can be wrapped */
-
-/*
- * Make an entry of the ring buffer invalid.
- */
-static inline void invalidate_xhlock(struct hist_lock *xhlock)
-{
- /*
- * Normally, xhlock->hlock.instance must be !NULL.
- */
- xhlock->hlock.instance = NULL;
-}
-
-/*
- * Lock history stacks; we have 2 nested lock history stacks:
- *
- * HARD(IRQ)
- * SOFT(IRQ)
- *
- * The thing is that once we complete a HARD/SOFT IRQ the future task locks
- * should not depend on any of the locks observed while running the IRQ. So
- * what we do is rewind the history buffer and erase all our knowledge of that
- * temporal event.
- */
-
-void crossrelease_hist_start(enum xhlock_context_t c)
-{
- struct task_struct *cur = current;
-
- if (!cur->xhlocks)
- return;
-
- cur->xhlock_idx_hist[c] = cur->xhlock_idx;
- cur->hist_id_save[c] = cur->hist_id;
-}
-
-void crossrelease_hist_end(enum xhlock_context_t c)
-{
- struct task_struct *cur = current;
-
- if (cur->xhlocks) {
- unsigned int idx = cur->xhlock_idx_hist[c];
- struct hist_lock *h = &xhlock(idx);
-
- cur->xhlock_idx = idx;
-
- /* Check if the ring was overwritten. */
- if (h->hist_id != cur->hist_id_save[c])
- invalidate_xhlock(h);
- }
-}
-
-/*
- * lockdep_invariant_state() is used to annotate independence inside a task, to
- * make one task look like multiple independent 'tasks'.
- *
- * Take for instance workqueues; each work is independent of the last. The
- * completion of a future work does not depend on the completion of a past work
- * (in general). Therefore we must not carry that (lock) dependency across
- * works.
- *
- * This is true for many things; pretty much all kthreads fall into this
- * pattern, where they have an invariant state and future completions do not
- * depend on past completions. Its just that since they all have the 'same'
- * form -- the kthread does the same over and over -- it doesn't typically
- * matter.
- *
- * The same is true for system-calls, once a system call is completed (we've
- * returned to userspace) the next system call does not depend on the lock
- * history of the previous system call.
- *
- * They key property for independence, this invariant state, is that it must be
- * a point where we hold no locks and have no history. Because if we were to
- * hold locks, the restore at _end() would not necessarily recover it's history
- * entry. Similarly, independence per-definition means it does not depend on
- * prior state.
- */
-void lockdep_invariant_state(bool force)
-{
- /*
- * We call this at an invariant point, no current state, no history.
- * Verify the former, enforce the latter.
- */
- WARN_ON_ONCE(!force && current->lockdep_depth);
- invalidate_xhlock(&xhlock(current->xhlock_idx));
-}
-
-static int cross_lock(struct lockdep_map *lock)
-{
- return lock ? lock->cross : 0;
-}
-
-/*
- * This is needed to decide the relationship between wrapable variables.
- */
-static inline int before(unsigned int a, unsigned int b)
-{
- return (int)(a - b) < 0;
-}
-
-static inline struct lock_class *xhlock_class(struct hist_lock *xhlock)
-{
- return hlock_class(&xhlock->hlock);
-}
-
-static inline struct lock_class *xlock_class(struct cross_lock *xlock)
-{
- return hlock_class(&xlock->hlock);
-}
-
-/*
- * Should we check a dependency with previous one?
- */
-static inline int depend_before(struct held_lock *hlock)
-{
- return hlock->read != 2 && hlock->check && !hlock->trylock;
-}
-
-/*
- * Should we check a dependency with next one?
- */
-static inline int depend_after(struct held_lock *hlock)
-{
- return hlock->read != 2 && hlock->check;
-}
-
-/*
- * Check if the xhlock is valid, which would be false if,
- *
- * 1. Has not used after initializaion yet.
- * 2. Got invalidated.
- *
- * Remind hist_lock is implemented as a ring buffer.
- */
-static inline int xhlock_valid(struct hist_lock *xhlock)
-{
- /*
- * xhlock->hlock.instance must be !NULL.
- */
- return !!xhlock->hlock.instance;
-}
-
-/*
- * Record a hist_lock entry.
- *
- * Irq disable is only required.
- */
-static void add_xhlock(struct held_lock *hlock)
-{
- unsigned int idx = ++current->xhlock_idx;
- struct hist_lock *xhlock = &xhlock(idx);
-
-#ifdef CONFIG_DEBUG_LOCKDEP
- /*
- * This can be done locklessly because they are all task-local
- * state, we must however ensure IRQs are disabled.
- */
- WARN_ON_ONCE(!irqs_disabled());
-#endif
-
- /* Initialize hist_lock's members */
- xhlock->hlock = *hlock;
- xhlock->hist_id = ++current->hist_id;
-
- xhlock->trace.nr_entries = 0;
- xhlock->trace.max_entries = MAX_XHLOCK_TRACE_ENTRIES;
- xhlock->trace.entries = xhlock->trace_entries;
- xhlock->trace.skip = 3;
- save_stack_trace(&xhlock->trace);
-}
-
-static inline int same_context_xhlock(struct hist_lock *xhlock)
-{
- return xhlock->hlock.irq_context == task_irq_context(current);
-}
-
-/*
- * This should be lockless as far as possible because this would be
- * called very frequently.
- */
-static void check_add_xhlock(struct held_lock *hlock)
-{
- /*
- * Record a hist_lock, only in case that acquisitions ahead
- * could depend on the held_lock. For example, if the held_lock
- * is trylock then acquisitions ahead never depends on that.
- * In that case, we don't need to record it. Just return.
- */
- if (!current->xhlocks || !depend_before(hlock))
- return;
-
- add_xhlock(hlock);
-}
-
-/*
- * For crosslock.
- */
-static int add_xlock(struct held_lock *hlock)
-{
- struct cross_lock *xlock;
- unsigned int gen_id;
-
- if (!graph_lock())
- return 0;
-
- xlock = &((struct lockdep_map_cross *)hlock->instance)->xlock;
-
- /*
- * When acquisitions for a crosslock are overlapped, we use
- * nr_acquire to perform commit for them, based on cross_gen_id
- * of the first acquisition, which allows to add additional
- * dependencies.
- *
- * Moreover, when no acquisition of a crosslock is in progress,
- * we should not perform commit because the lock might not exist
- * any more, which might cause incorrect memory access. So we
- * have to track the number of acquisitions of a crosslock.
- *
- * depend_after() is necessary to initialize only the first
- * valid xlock so that the xlock can be used on its commit.
- */
- if (xlock->nr_acquire++ && depend_after(&xlock->hlock))
- goto unlock;
-
- gen_id = (unsigned int)atomic_inc_return(&cross_gen_id);
- xlock->hlock = *hlock;
- xlock->hlock.gen_id = gen_id;
-unlock:
- graph_unlock();
- return 1;
-}
-
-/*
- * Called for both normal and crosslock acquires. Normal locks will be
- * pushed on the hist_lock queue. Cross locks will record state and
- * stop regular lock_acquire() to avoid being placed on the held_lock
- * stack.
- *
- * Return: 0 - failure;
- * 1 - crosslock, done;
- * 2 - normal lock, continue to held_lock[] ops.
- */
-static int lock_acquire_crosslock(struct held_lock *hlock)
-{
- /*
- * CONTEXT 1 CONTEXT 2
- * --------- ---------
- * lock A (cross)
- * X = atomic_inc_return(&cross_gen_id)
- * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- * Y = atomic_read_acquire(&cross_gen_id)
- * lock B
- *
- * atomic_read_acquire() is for ordering between A and B,
- * IOW, A happens before B, when CONTEXT 2 see Y >= X.
- *
- * Pairs with atomic_inc_return() in add_xlock().
- */
- hlock->gen_id = (unsigned int)atomic_read_acquire(&cross_gen_id);
-
- if (cross_lock(hlock->instance))
- return add_xlock(hlock);
-
- check_add_xhlock(hlock);
- return 2;
-}
-
-static int copy_trace(struct stack_trace *trace)
-{
- unsigned long *buf = stack_trace + nr_stack_trace_entries;
- unsigned int max_nr = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
- unsigned int nr = min(max_nr, trace->nr_entries);
-
- trace->nr_entries = nr;
- memcpy(buf, trace->entries, nr * sizeof(trace->entries[0]));
- trace->entries = buf;
- nr_stack_trace_entries += nr;
-
- if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
- if (!debug_locks_off_graph_unlock())
- return 0;
-
- print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
- dump_stack();
-
- return 0;
- }
-
- return 1;
-}
-
-static int commit_xhlock(struct cross_lock *xlock, struct hist_lock *xhlock)
-{
- unsigned int xid, pid;
- u64 chain_key;
-
- xid = xlock_class(xlock) - lock_classes;
- chain_key = iterate_chain_key((u64)0, xid);
- pid = xhlock_class(xhlock) - lock_classes;
- chain_key = iterate_chain_key(chain_key, pid);
-
- if (lookup_chain_cache(chain_key))
- return 1;
-
- if (!add_chain_cache_classes(xid, pid, xhlock->hlock.irq_context,
- chain_key))
- return 0;
-
- if (!check_prev_add(current, &xlock->hlock, &xhlock->hlock, 1,
- &xhlock->trace, copy_trace))
- return 0;
-
- return 1;
-}
-
-static void commit_xhlocks(struct cross_lock *xlock)
-{
- unsigned int cur = current->xhlock_idx;
- unsigned int prev_hist_id = xhlock(cur).hist_id;
- unsigned int i;
-
- if (!graph_lock())
- return;
-
- if (xlock->nr_acquire) {
- for (i = 0; i < MAX_XHLOCKS_NR; i++) {
- struct hist_lock *xhlock = &xhlock(cur - i);
-
- if (!xhlock_valid(xhlock))
- break;
-
- if (before(xhlock->hlock.gen_id, xlock->hlock.gen_id))
- break;
-
- if (!same_context_xhlock(xhlock))
- break;
-
- /*
- * Filter out the cases where the ring buffer was
- * overwritten and the current entry has a bigger
- * hist_id than the previous one, which is impossible
- * otherwise:
- */
- if (unlikely(before(prev_hist_id, xhlock->hist_id)))
- break;
-
- prev_hist_id = xhlock->hist_id;
-
- /*
- * commit_xhlock() returns 0 with graph_lock already
- * released if fail.
- */
- if (!commit_xhlock(xlock, xhlock))
- return;
- }
- }
-
- graph_unlock();
-}
-
-void lock_commit_crosslock(struct lockdep_map *lock)
-{
- struct cross_lock *xlock;
- unsigned long flags;
-
- if (unlikely(!debug_locks || current->lockdep_recursion))
- return;
-
- if (!current->xhlocks)
- return;
-
- /*
- * Do commit hist_locks with the cross_lock, only in case that
- * the cross_lock could depend on acquisitions after that.
- *
- * For example, if the cross_lock does not have the 'check' flag
- * then we don't need to check dependencies and commit for that.
- * Just skip it. In that case, of course, the cross_lock does
- * not depend on acquisitions ahead, either.
- *
- * WARNING: Don't do that in add_xlock() in advance. When an
- * acquisition context is different from the commit context,
- * invalid(skipped) cross_lock might be accessed.
- */
- if (!depend_after(&((struct lockdep_map_cross *)lock)->xlock.hlock))
- return;
-
- raw_local_irq_save(flags);
- check_flags(flags);
- current->lockdep_recursion = 1;
- xlock = &((struct lockdep_map_cross *)lock)->xlock;
- commit_xhlocks(xlock);
- current->lockdep_recursion = 0;
- raw_local_irq_restore(flags);
-}
-EXPORT_SYMBOL_GPL(lock_commit_crosslock);
-
-/*
- * Return: 0 - failure;
- * 1 - crosslock, done;
- * 2 - normal lock, continue to held_lock[] ops.
- */
-static int lock_release_crosslock(struct lockdep_map *lock)
-{
- if (cross_lock(lock)) {
- if (!graph_lock())
- return 0;
- ((struct lockdep_map_cross *)lock)->xlock.nr_acquire--;
- graph_unlock();
- return 1;
- }
- return 2;
-}
-
-static void cross_init(struct lockdep_map *lock, int cross)
-{
- if (cross)
- ((struct lockdep_map_cross *)lock)->xlock.nr_acquire = 0;
-
- lock->cross = cross;
-
- /*
- * Crossrelease assumes that the ring buffer size of xhlocks
- * is aligned with power of 2. So force it on build.
- */
- BUILD_BUG_ON(MAX_XHLOCKS_NR & (MAX_XHLOCKS_NR - 1));
-}
-
-void lockdep_init_task(struct task_struct *task)
-{
- int i;
-
- task->xhlock_idx = UINT_MAX;
- task->hist_id = 0;
-
- for (i = 0; i < XHLOCK_CTX_NR; i++) {
- task->xhlock_idx_hist[i] = UINT_MAX;
- task->hist_id_save[i] = 0;
- }
-
- task->xhlocks = kzalloc(sizeof(struct hist_lock) * MAX_XHLOCKS_NR,
- GFP_KERNEL);
-}
-
-void lockdep_free_task(struct task_struct *task)
-{
- if (task->xhlocks) {
- void *tmp = task->xhlocks;
- /* Diable crossrelease for current */
- task->xhlocks = NULL;
- kfree(tmp);
- }
-}
-#endif
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index 1da4669d57a7..d459d624ba2a 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
/*
* kernel/lockdep_internals.h
*
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index 68d9e267ccd4..ad69bbc9bd28 100644
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
/*
* kernel/lockdep_proc.c
*
diff --git a/kernel/locking/mcs_spinlock.h b/kernel/locking/mcs_spinlock.h
index 6a385aabcce7..f046b7ce9dd6 100644
--- a/kernel/locking/mcs_spinlock.h
+++ b/kernel/locking/mcs_spinlock.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
/*
* MCS lock defines
*
diff --git a/kernel/locking/mutex-debug.h b/kernel/locking/mutex-debug.h
index 4174417d5309..1edd3f45a4ec 100644
--- a/kernel/locking/mutex-debug.h
+++ b/kernel/locking/mutex-debug.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
/*
* Mutexes: blocking mutual exclusion locks
*
diff --git a/kernel/locking/mutex.h b/kernel/locking/mutex.h
index 6ebc1902f779..1c2287d3fa71 100644
--- a/kernel/locking/mutex.h
+++ b/kernel/locking/mutex.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
/*
* Mutexes: blocking mutual exclusion locks
*
diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c
index a74ee6abd039..6ef600aa0f47 100644
--- a/kernel/locking/osq_lock.c
+++ b/kernel/locking/osq_lock.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/osq_lock.h>
diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c
index 2655f26ec882..c7471c3fb798 100644
--- a/kernel/locking/qrwlock.c
+++ b/kernel/locking/qrwlock.c
@@ -23,49 +23,11 @@
#include <linux/spinlock.h>
#include <asm/qrwlock.h>
-/*
- * This internal data structure is used for optimizing access to some of
- * the subfields within the atomic_t cnts.
- */
-struct __qrwlock {
- union {
- atomic_t cnts;
- struct {
-#ifdef __LITTLE_ENDIAN
- u8 wmode; /* Writer mode */
- u8 rcnts[3]; /* Reader counts */
-#else
- u8 rcnts[3]; /* Reader counts */
- u8 wmode; /* Writer mode */
-#endif
- };
- };
- arch_spinlock_t lock;
-};
-
-/**
- * rspin_until_writer_unlock - inc reader count & spin until writer is gone
- * @lock : Pointer to queue rwlock structure
- * @writer: Current queue rwlock writer status byte
- *
- * In interrupt context or at the head of the queue, the reader will just
- * increment the reader count & wait until the writer releases the lock.
- */
-static __always_inline void
-rspin_until_writer_unlock(struct qrwlock *lock, u32 cnts)
-{
- while ((cnts & _QW_WMASK) == _QW_LOCKED) {
- cpu_relax();
- cnts = atomic_read_acquire(&lock->cnts);
- }
-}
-
/**
* queued_read_lock_slowpath - acquire read lock of a queue rwlock
* @lock: Pointer to queue rwlock structure
- * @cnts: Current qrwlock lock value
*/
-void queued_read_lock_slowpath(struct qrwlock *lock, u32 cnts)
+void queued_read_lock_slowpath(struct qrwlock *lock)
{
/*
* Readers come here when they cannot get the lock without waiting
@@ -73,13 +35,11 @@ void queued_read_lock_slowpath(struct qrwlock *lock, u32 cnts)
if (unlikely(in_interrupt())) {
/*
* Readers in interrupt context will get the lock immediately
- * if the writer is just waiting (not holding the lock yet).
- * The rspin_until_writer_unlock() function returns immediately
- * in this case. Otherwise, they will spin (with ACQUIRE
- * semantics) until the lock is available without waiting in
- * the queue.
+ * if the writer is just waiting (not holding the lock yet),
+ * so spin with ACQUIRE semantics until the lock is available
+ * without waiting in the queue.
*/
- rspin_until_writer_unlock(lock, cnts);
+ atomic_cond_read_acquire(&lock->cnts, !(VAL & _QW_LOCKED));
return;
}
atomic_sub(_QR_BIAS, &lock->cnts);
@@ -88,14 +48,14 @@ void queued_read_lock_slowpath(struct qrwlock *lock, u32 cnts)
* Put the reader into the wait queue
*/
arch_spin_lock(&lock->wait_lock);
+ atomic_add(_QR_BIAS, &lock->cnts);
/*
* The ACQUIRE semantics of the following spinning code ensure
* that accesses can't leak upwards out of our subsequent critical
* section in the case that the lock is currently held for write.
*/
- cnts = atomic_fetch_add_acquire(_QR_BIAS, &lock->cnts);
- rspin_until_writer_unlock(lock, cnts);
+ atomic_cond_read_acquire(&lock->cnts, !(VAL & _QW_LOCKED));
/*
* Signal the next one in queue to become queue head
@@ -110,8 +70,6 @@ EXPORT_SYMBOL(queued_read_lock_slowpath);
*/
void queued_write_lock_slowpath(struct qrwlock *lock)
{
- u32 cnts;
-
/* Put the writer into the wait queue */
arch_spin_lock(&lock->wait_lock);
@@ -120,30 +78,14 @@ void queued_write_lock_slowpath(struct qrwlock *lock)
(atomic_cmpxchg_acquire(&lock->cnts, 0, _QW_LOCKED) == 0))
goto unlock;
- /*
- * Set the waiting flag to notify readers that a writer is pending,
- * or wait for a previous writer to go away.
- */
- for (;;) {
- struct __qrwlock *l = (struct __qrwlock *)lock;
-
- if (!READ_ONCE(l->wmode) &&
- (cmpxchg_relaxed(&l->wmode, 0, _QW_WAITING) == 0))
- break;
+ /* Set the waiting flag to notify readers that a writer is pending */
+ atomic_add(_QW_WAITING, &lock->cnts);
- cpu_relax();
- }
-
- /* When no more readers, set the locked flag */
- for (;;) {
- cnts = atomic_read(&lock->cnts);
- if ((cnts == _QW_WAITING) &&
- (atomic_cmpxchg_acquire(&lock->cnts, _QW_WAITING,
- _QW_LOCKED) == _QW_WAITING))
- break;
-
- cpu_relax();
- }
+ /* When no more readers or writers, set the locked flag */
+ do {
+ atomic_cond_read_acquire(&lock->cnts, VAL == _QW_WAITING);
+ } while (atomic_cmpxchg_relaxed(&lock->cnts, _QW_WAITING,
+ _QW_LOCKED) != _QW_WAITING);
unlock:
arch_spin_unlock(&lock->wait_lock);
}
diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
index 43555681c40b..6ee477765e6c 100644
--- a/kernel/locking/qspinlock_paravirt.h
+++ b/kernel/locking/qspinlock_paravirt.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _GEN_PV_LOCK_SLOWPATH
#error "do not include this file"
#endif
@@ -60,21 +61,50 @@ struct pv_node {
#include "qspinlock_stat.h"
/*
+ * Hybrid PV queued/unfair lock
+ *
* By replacing the regular queued_spin_trylock() with the function below,
* it will be called once when a lock waiter enter the PV slowpath before
- * being queued. By allowing one lock stealing attempt here when the pending
- * bit is off, it helps to reduce the performance impact of lock waiter
- * preemption without the drawback of lock starvation.
+ * being queued.
+ *
+ * The pending bit is set by the queue head vCPU of the MCS wait queue in
+ * pv_wait_head_or_lock() to signal that it is ready to spin on the lock.
+ * When that bit becomes visible to the incoming waiters, no lock stealing
+ * is allowed. The function will return immediately to make the waiters
+ * enter the MCS wait queue. So lock starvation shouldn't happen as long
+ * as the queued mode vCPUs are actively running to set the pending bit
+ * and hence disabling lock stealing.
+ *
+ * When the pending bit isn't set, the lock waiters will stay in the unfair
+ * mode spinning on the lock unless the MCS wait queue is empty. In this
+ * case, the lock waiters will enter the queued mode slowpath trying to
+ * become the queue head and set the pending bit.
+ *
+ * This hybrid PV queued/unfair lock combines the best attributes of a
+ * queued lock (no lock starvation) and an unfair lock (good performance
+ * on not heavily contended locks).
*/
-#define queued_spin_trylock(l) pv_queued_spin_steal_lock(l)
-static inline bool pv_queued_spin_steal_lock(struct qspinlock *lock)
+#define queued_spin_trylock(l) pv_hybrid_queued_unfair_trylock(l)
+static inline bool pv_hybrid_queued_unfair_trylock(struct qspinlock *lock)
{
struct __qspinlock *l = (void *)lock;
- if (!(atomic_read(&lock->val) & _Q_LOCKED_PENDING_MASK) &&
- (cmpxchg_acquire(&l->locked, 0, _Q_LOCKED_VAL) == 0)) {
- qstat_inc(qstat_pv_lock_stealing, true);
- return true;
+ /*
+ * Stay in unfair lock mode as long as queued mode waiters are
+ * present in the MCS wait queue but the pending bit isn't set.
+ */
+ for (;;) {
+ int val = atomic_read(&lock->val);
+
+ if (!(val & _Q_LOCKED_PENDING_MASK) &&
+ (cmpxchg_acquire(&l->locked, 0, _Q_LOCKED_VAL) == 0)) {
+ qstat_inc(qstat_pv_lock_stealing, true);
+ return true;
+ }
+ if (!(val & _Q_TAIL_MASK) || (val & _Q_PENDING_MASK))
+ break;
+
+ cpu_relax();
}
return false;
diff --git a/kernel/locking/rtmutex-debug.c b/kernel/locking/rtmutex-debug.c
index f4a74e78d467..fd4fe1f5b458 100644
--- a/kernel/locking/rtmutex-debug.c
+++ b/kernel/locking/rtmutex-debug.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
/*
* RT-Mutexes: blocking mutual exclusion locks with PI support
*
diff --git a/kernel/locking/rtmutex-debug.h b/kernel/locking/rtmutex-debug.h
index 5078c6ddf4a5..fc549713bba3 100644
--- a/kernel/locking/rtmutex-debug.h
+++ b/kernel/locking/rtmutex-debug.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
/*
* RT-Mutexes: blocking mutual exclusion locks with PI support
*
diff --git a/kernel/locking/rtmutex.h b/kernel/locking/rtmutex.h
index 5c253caffe91..732f96abf462 100644
--- a/kernel/locking/rtmutex.h
+++ b/kernel/locking/rtmutex.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
/*
* RT-Mutexes: blocking mutual exclusion locks with PI support
*
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index 7453be0485a5..124e98ca0b17 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
/*
* RT Mutexes: blocking mutual exclusion locks with PI support
*
diff --git a/kernel/locking/rwsem-spinlock.c b/kernel/locking/rwsem-spinlock.c
index 0848634c5512..a7ffb2a96ede 100644
--- a/kernel/locking/rwsem-spinlock.c
+++ b/kernel/locking/rwsem-spinlock.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
/* rwsem-spinlock.c: R/W semaphores: contention handling functions for
* generic spinlock implementation
*
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index 1fefe6dcafd7..e795908f3607 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
/* rwsem.c: R/W semaphores: contention handling functions
*
* Written by David Howells ([email protected]).
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 4d48b1c4870d..f549c552dbf1 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
/* kernel/rwsem.c: R/W semaphores, public implementation
*
* Written by David Howells ([email protected]).
@@ -28,6 +29,22 @@ void __sched down_read(struct rw_semaphore *sem)
EXPORT_SYMBOL(down_read);
+int __sched down_read_killable(struct rw_semaphore *sem)
+{
+ might_sleep();
+ rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
+
+ if (LOCK_CONTENDED_RETURN(sem, __down_read_trylock, __down_read_killable)) {
+ rwsem_release(&sem->dep_map, 1, _RET_IP_);
+ return -EINTR;
+ }
+
+ rwsem_set_reader_owned(sem);
+ return 0;
+}
+
+EXPORT_SYMBOL(down_read_killable);
+
/*
* trylock for reading -- returns 1 if successful, 0 if contention
*/
diff --git a/kernel/locking/rwsem.h b/kernel/locking/rwsem.h
index a699f4048ba1..a883b8f1fdc6 100644
--- a/kernel/locking/rwsem.h
+++ b/kernel/locking/rwsem.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
/*
* The owner field of the rw_semaphore structure will be set to
* RWSEM_READ_OWNED when a reader grabs the lock. A writer will clear
diff --git a/kernel/locking/spinlock.c b/kernel/locking/spinlock.c
index 4b082b5cac9e..936f3d14dd6b 100644
--- a/kernel/locking/spinlock.c
+++ b/kernel/locking/spinlock.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (2004) Linus Torvalds
*
@@ -29,11 +30,10 @@
#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
/*
* The __lock_function inlines are taken from
- * include/linux/spinlock_api_smp.h
+ * spinlock : include/linux/spinlock_api_smp.h
+ * rwlock : include/linux/rwlock_api_smp.h
*/
#else
-#define raw_read_can_lock(l) read_can_lock(l)
-#define raw_write_can_lock(l) write_can_lock(l)
/*
* Some architectures can relax in favour of the CPU owning the lock.
@@ -66,12 +66,8 @@ void __lockfunc __raw_##op##_lock(locktype##_t *lock) \
break; \
preempt_enable(); \
\
- if (!(lock)->break_lock) \
- (lock)->break_lock = 1; \
- while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
- arch_##op##_relax(&lock->raw_lock); \
+ arch_##op##_relax(&lock->raw_lock); \
} \
- (lock)->break_lock = 0; \
} \
\
unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock) \
@@ -86,12 +82,9 @@ unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock) \
local_irq_restore(flags); \
preempt_enable(); \
\
- if (!(lock)->break_lock) \
- (lock)->break_lock = 1; \
- while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
- arch_##op##_relax(&lock->raw_lock); \
+ arch_##op##_relax(&lock->raw_lock); \
} \
- (lock)->break_lock = 0; \
+ \
return flags; \
} \
\
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