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author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-03 23:39:35 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-03 23:39:35 +0200 |
commit | 9ba19ccd2d283a79dd29e8130819c59beca80f62 (patch) | |
tree | 8dece4ee137bc9f7a3e5f31ce5613f9b82b7d260 /kernel/locking | |
parent | Merge tag 'core-rcu-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/... (diff) | |
parent | Merge branch 'locking/nmi' into locking/core, to pick up completed topic branch (diff) | |
download | linux-9ba19ccd2d283a79dd29e8130819c59beca80f62.tar.xz linux-9ba19ccd2d283a79dd29e8130819c59beca80f62.zip |
Merge tag 'locking-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
- LKMM updates: mostly documentation changes, but also some new litmus
tests for atomic ops.
- KCSAN updates: the most important change is that GCC 11 now has all
fixes in place to support KCSAN, so GCC support can be enabled again.
Also more annotations.
- futex updates: minor cleanups and simplifications
- seqlock updates: merge preparatory changes/cleanups for the
'associated locks' facilities.
- lockdep updates:
- simplify IRQ trace event handling
- add various new debug checks
- simplify header dependencies, split out <linux/lockdep_types.h>,
decouple lockdep from other low level headers some more
- fix NMI handling
- misc cleanups and smaller fixes
* tag 'locking-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
kcsan: Improve IRQ state trace reporting
lockdep: Refactor IRQ trace events fields into struct
seqlock: lockdep assert non-preemptibility on seqcount_t write
lockdep: Add preemption enabled/disabled assertion APIs
seqlock: Implement raw_seqcount_begin() in terms of raw_read_seqcount()
seqlock: Add kernel-doc for seqcount_t and seqlock_t APIs
seqlock: Reorder seqcount_t and seqlock_t API definitions
seqlock: seqcount_t latch: End read sections with read_seqcount_retry()
seqlock: Properly format kernel-doc code samples
Documentation: locking: Describe seqlock design and usage
locking/qspinlock: Do not include atomic.h from qspinlock_types.h
locking/atomic: Move ATOMIC_INIT into linux/types.h
lockdep: Move list.h inclusion into lockdep.h
locking/lockdep: Fix TRACE_IRQFLAGS vs. NMIs
futex: Remove unused or redundant includes
futex: Consistently use fshared as boolean
futex: Remove needless goto's
futex: Remove put_futex_key()
rwsem: fix commas in initialisation
docs: locking: Replace HTTP links with HTTPS ones
...
Diffstat (limited to 'kernel/locking')
-rw-r--r-- | kernel/locking/lockdep.c | 142 | ||||
-rw-r--r-- | kernel/locking/osq_lock.c | 6 |
2 files changed, 99 insertions, 49 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 0a7549d159ed..f361d75a75ac 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -395,7 +395,7 @@ void lockdep_init_task(struct task_struct *task) static __always_inline void lockdep_recursion_finish(void) { - if (WARN_ON_ONCE(--current->lockdep_recursion)) + if (WARN_ON_ONCE((--current->lockdep_recursion) & LOCKDEP_RECURSION_MASK)) current->lockdep_recursion = 0; } @@ -2062,9 +2062,9 @@ print_bad_irq_dependency(struct task_struct *curr, pr_warn("-----------------------------------------------------\n"); pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", curr->comm, task_pid_nr(curr), - curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, + lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT, curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, - curr->hardirqs_enabled, + lockdep_hardirqs_enabled(), curr->softirqs_enabled); print_lock(next); @@ -3331,9 +3331,9 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this, pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", curr->comm, task_pid_nr(curr), - lockdep_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, + lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT, lockdep_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, - lockdep_hardirqs_enabled(curr), + lockdep_hardirqs_enabled(), lockdep_softirqs_enabled(curr)); print_lock(this); @@ -3484,19 +3484,21 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this, void print_irqtrace_events(struct task_struct *curr) { - printk("irq event stamp: %u\n", curr->irq_events); + const struct irqtrace_events *trace = &curr->irqtrace; + + printk("irq event stamp: %u\n", trace->irq_events); printk("hardirqs last enabled at (%u): [<%px>] %pS\n", - curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip, - (void *)curr->hardirq_enable_ip); + trace->hardirq_enable_event, (void *)trace->hardirq_enable_ip, + (void *)trace->hardirq_enable_ip); printk("hardirqs last disabled at (%u): [<%px>] %pS\n", - curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip, - (void *)curr->hardirq_disable_ip); + trace->hardirq_disable_event, (void *)trace->hardirq_disable_ip, + (void *)trace->hardirq_disable_ip); printk("softirqs last enabled at (%u): [<%px>] %pS\n", - curr->softirq_enable_event, (void *)curr->softirq_enable_ip, - (void *)curr->softirq_enable_ip); + trace->softirq_enable_event, (void *)trace->softirq_enable_ip, + (void *)trace->softirq_enable_ip); printk("softirqs last disabled at (%u): [<%px>] %pS\n", - curr->softirq_disable_event, (void *)curr->softirq_disable_ip, - (void *)curr->softirq_disable_ip); + trace->softirq_disable_event, (void *)trace->softirq_disable_ip, + (void *)trace->softirq_disable_ip); } static int HARDIRQ_verbose(struct lock_class *class) @@ -3646,10 +3648,19 @@ static void __trace_hardirqs_on_caller(void) */ void lockdep_hardirqs_on_prepare(unsigned long ip) { - if (unlikely(!debug_locks || current->lockdep_recursion)) + if (unlikely(!debug_locks)) + return; + + /* + * NMIs do not (and cannot) track lock dependencies, nothing to do. + */ + if (unlikely(in_nmi())) + return; + + if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK)) return; - if (unlikely(current->hardirqs_enabled)) { + if (unlikely(lockdep_hardirqs_enabled())) { /* * Neither irq nor preemption are disabled here * so this is racy by nature but losing one hit @@ -3677,7 +3688,7 @@ void lockdep_hardirqs_on_prepare(unsigned long ip) * Can't allow enabling interrupts while in an interrupt handler, * that's general bad form and such. Recursion, limited stack etc.. */ - if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) + if (DEBUG_LOCKS_WARN_ON(lockdep_hardirq_context())) return; current->hardirq_chain_key = current->curr_chain_key; @@ -3690,12 +3701,35 @@ EXPORT_SYMBOL_GPL(lockdep_hardirqs_on_prepare); void noinstr lockdep_hardirqs_on(unsigned long ip) { - struct task_struct *curr = current; + struct irqtrace_events *trace = ¤t->irqtrace; + + if (unlikely(!debug_locks)) + return; + + /* + * NMIs can happen in the middle of local_irq_{en,dis}able() where the + * tracking state and hardware state are out of sync. + * + * NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from, + * and not rely on hardware state like normal interrupts. + */ + if (unlikely(in_nmi())) { + if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI)) + return; + + /* + * Skip: + * - recursion check, because NMI can hit lockdep; + * - hardware state check, because above; + * - chain_key check, see lockdep_hardirqs_on_prepare(). + */ + goto skip_checks; + } - if (unlikely(!debug_locks || curr->lockdep_recursion)) + if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK)) return; - if (curr->hardirqs_enabled) { + if (lockdep_hardirqs_enabled()) { /* * Neither irq nor preemption are disabled here * so this is racy by nature but losing one hit @@ -3720,10 +3754,11 @@ void noinstr lockdep_hardirqs_on(unsigned long ip) DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key != current->curr_chain_key); +skip_checks: /* we'll do an OFF -> ON transition: */ - curr->hardirqs_enabled = 1; - curr->hardirq_enable_ip = ip; - curr->hardirq_enable_event = ++curr->irq_events; + this_cpu_write(hardirqs_enabled, 1); + trace->hardirq_enable_ip = ip; + trace->hardirq_enable_event = ++trace->irq_events; debug_atomic_inc(hardirqs_on_events); } EXPORT_SYMBOL_GPL(lockdep_hardirqs_on); @@ -3733,9 +3768,18 @@ EXPORT_SYMBOL_GPL(lockdep_hardirqs_on); */ void noinstr lockdep_hardirqs_off(unsigned long ip) { - struct task_struct *curr = current; + if (unlikely(!debug_locks)) + return; - if (unlikely(!debug_locks || curr->lockdep_recursion)) + /* + * Matching lockdep_hardirqs_on(), allow NMIs in the middle of lockdep; + * they will restore the software state. This ensures the software + * state is consistent inside NMIs as well. + */ + if (in_nmi()) { + if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI)) + return; + } else if (current->lockdep_recursion & LOCKDEP_RECURSION_MASK) return; /* @@ -3745,13 +3789,15 @@ void noinstr lockdep_hardirqs_off(unsigned long ip) if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return; - if (curr->hardirqs_enabled) { + if (lockdep_hardirqs_enabled()) { + struct irqtrace_events *trace = ¤t->irqtrace; + /* * We have done an ON -> OFF transition: */ - curr->hardirqs_enabled = 0; - curr->hardirq_disable_ip = ip; - curr->hardirq_disable_event = ++curr->irq_events; + this_cpu_write(hardirqs_enabled, 0); + trace->hardirq_disable_ip = ip; + trace->hardirq_disable_event = ++trace->irq_events; debug_atomic_inc(hardirqs_off_events); } else { debug_atomic_inc(redundant_hardirqs_off); @@ -3764,7 +3810,7 @@ EXPORT_SYMBOL_GPL(lockdep_hardirqs_off); */ void lockdep_softirqs_on(unsigned long ip) { - struct task_struct *curr = current; + struct irqtrace_events *trace = ¤t->irqtrace; if (unlikely(!debug_locks || current->lockdep_recursion)) return; @@ -3776,7 +3822,7 @@ void lockdep_softirqs_on(unsigned long ip) if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return; - if (curr->softirqs_enabled) { + if (current->softirqs_enabled) { debug_atomic_inc(redundant_softirqs_on); return; } @@ -3785,17 +3831,17 @@ void lockdep_softirqs_on(unsigned long ip) /* * We'll do an OFF -> ON transition: */ - curr->softirqs_enabled = 1; - curr->softirq_enable_ip = ip; - curr->softirq_enable_event = ++curr->irq_events; + current->softirqs_enabled = 1; + trace->softirq_enable_ip = ip; + trace->softirq_enable_event = ++trace->irq_events; debug_atomic_inc(softirqs_on_events); /* * We are going to turn softirqs on, so set the * usage bit for all held locks, if hardirqs are * enabled too: */ - if (curr->hardirqs_enabled) - mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ); + if (lockdep_hardirqs_enabled()) + mark_held_locks(current, LOCK_ENABLED_SOFTIRQ); lockdep_recursion_finish(); } @@ -3804,8 +3850,6 @@ void lockdep_softirqs_on(unsigned long ip) */ void lockdep_softirqs_off(unsigned long ip) { - struct task_struct *curr = current; - if (unlikely(!debug_locks || current->lockdep_recursion)) return; @@ -3815,13 +3859,15 @@ void lockdep_softirqs_off(unsigned long ip) if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return; - if (curr->softirqs_enabled) { + if (current->softirqs_enabled) { + struct irqtrace_events *trace = ¤t->irqtrace; + /* * We have done an ON -> OFF transition: */ - curr->softirqs_enabled = 0; - curr->softirq_disable_ip = ip; - curr->softirq_disable_event = ++curr->irq_events; + current->softirqs_enabled = 0; + trace->softirq_disable_ip = ip; + trace->softirq_disable_event = ++trace->irq_events; debug_atomic_inc(softirqs_off_events); /* * Whoops, we wanted softirqs off, so why aren't they? @@ -3843,7 +3889,7 @@ mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) */ if (!hlock->trylock) { if (hlock->read) { - if (curr->hardirq_context) + if (lockdep_hardirq_context()) if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ_READ)) return 0; @@ -3852,7 +3898,7 @@ mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) LOCK_USED_IN_SOFTIRQ_READ)) return 0; } else { - if (curr->hardirq_context) + if (lockdep_hardirq_context()) if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) return 0; if (curr->softirq_context) @@ -3890,7 +3936,7 @@ lock_used: static inline unsigned int task_irq_context(struct task_struct *task) { - return LOCK_CHAIN_HARDIRQ_CONTEXT * !!task->hardirq_context + + return LOCK_CHAIN_HARDIRQ_CONTEXT * !!lockdep_hardirq_context() + LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context; } @@ -3983,7 +4029,7 @@ static inline short task_wait_context(struct task_struct *curr) * Set appropriate wait type for the context; for IRQs we have to take * into account force_irqthread as that is implied by PREEMPT_RT. */ - if (curr->hardirq_context) { + if (lockdep_hardirq_context()) { /* * Check if force_irqthreads will run us threaded. */ @@ -4826,11 +4872,11 @@ static void check_flags(unsigned long flags) return; if (irqs_disabled_flags(flags)) { - if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { + if (DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())) { printk("possible reason: unannotated irqs-off.\n"); } } else { - if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { + if (DEBUG_LOCKS_WARN_ON(!lockdep_hardirqs_enabled())) { printk("possible reason: unannotated irqs-on.\n"); } } diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c index 1f7734949ac8..1de006ed3aa8 100644 --- a/kernel/locking/osq_lock.c +++ b/kernel/locking/osq_lock.c @@ -154,7 +154,11 @@ bool osq_lock(struct optimistic_spin_queue *lock) */ for (;;) { - if (prev->next == node && + /* + * cpu_relax() below implies a compiler barrier which would + * prevent this comparison being optimized away. + */ + if (data_race(prev->next) == node && cmpxchg(&prev->next, node, NULL) == node) break; |