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author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-20 10:23:08 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-20 10:23:08 -0800 |
commit | 6ffbe7d1fabddc768724656f159759cae7818cd9 (patch) | |
tree | ece184db0c35bcd9606968303984b430c24b847f /kernel/softirq.c | |
parent | 897aea303fec0c24b2a21b8e29f45dc73a234555 (diff) | |
parent | 63b1a81699c2a45c9f737419b1ec1da0ecf92812 (diff) | |
download | lwn-6ffbe7d1fabddc768724656f159759cae7818cd9.tar.gz lwn-6ffbe7d1fabddc768724656f159759cae7818cd9.zip |
Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core locking changes from Ingo Molnar:
- futex performance increases: larger hashes, smarter wakeups
- mutex debugging improvements
- lots of SMP ordering documentation updates
- introduce the smp_load_acquire(), smp_store_release() primitives.
(There are WIP patches that make use of them - not yet merged)
- lockdep micro-optimizations
- lockdep improvement: better cover IRQ contexts
- liblockdep at last. We'll continue to monitor how useful this is
* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
futexes: Fix futex_hashsize initialization
arch: Re-sort some Kbuild files to hopefully help avoid some conflicts
futexes: Avoid taking the hb->lock if there's nothing to wake up
futexes: Document multiprocessor ordering guarantees
futexes: Increase hash table size for better performance
futexes: Clean up various details
arch: Introduce smp_load_acquire(), smp_store_release()
arch: Clean up asm/barrier.h implementations using asm-generic/barrier.h
arch: Move smp_mb__{before,after}_atomic_{inc,dec}.h into asm/atomic.h
locking/doc: Rename LOCK/UNLOCK to ACQUIRE/RELEASE
mutexes: Give more informative mutex warning in the !lock->owner case
powerpc: Full barrier for smp_mb__after_unlock_lock()
rcu: Apply smp_mb__after_unlock_lock() to preserve grace periods
Documentation/memory-barriers.txt: Downgrade UNLOCK+BLOCK
locking: Add an smp_mb__after_unlock_lock() for UNLOCK+BLOCK barrier
Documentation/memory-barriers.txt: Document ACCESS_ONCE()
Documentation/memory-barriers.txt: Prohibit speculative writes
Documentation/memory-barriers.txt: Add long atomic examples to memory-barriers.txt
Documentation/memory-barriers.txt: Add needed ACCESS_ONCE() calls to memory-barriers.txt
Revert "smp/cpumask: Make CONFIG_CPUMASK_OFFSTACK=y usable without debug dependency"
...
Diffstat (limited to 'kernel/softirq.c')
-rw-r--r-- | kernel/softirq.c | 49 |
1 files changed, 40 insertions, 9 deletions
diff --git a/kernel/softirq.c b/kernel/softirq.c index 11025ccc06dd..9a4500e4c189 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -211,14 +211,48 @@ EXPORT_SYMBOL(local_bh_enable_ip); #define MAX_SOFTIRQ_TIME msecs_to_jiffies(2) #define MAX_SOFTIRQ_RESTART 10 +#ifdef CONFIG_TRACE_IRQFLAGS +/* + * When we run softirqs from irq_exit() and thus on the hardirq stack we need + * to keep the lockdep irq context tracking as tight as possible in order to + * not miss-qualify lock contexts and miss possible deadlocks. + */ + +static inline bool lockdep_softirq_start(void) +{ + bool in_hardirq = false; + + if (trace_hardirq_context(current)) { + in_hardirq = true; + trace_hardirq_exit(); + } + + lockdep_softirq_enter(); + + return in_hardirq; +} + +static inline void lockdep_softirq_end(bool in_hardirq) +{ + lockdep_softirq_exit(); + + if (in_hardirq) + trace_hardirq_enter(); +} +#else +static inline bool lockdep_softirq_start(void) { return false; } +static inline void lockdep_softirq_end(bool in_hardirq) { } +#endif + asmlinkage void __do_softirq(void) { - struct softirq_action *h; - __u32 pending; unsigned long end = jiffies + MAX_SOFTIRQ_TIME; - int cpu; unsigned long old_flags = current->flags; int max_restart = MAX_SOFTIRQ_RESTART; + struct softirq_action *h; + bool in_hardirq; + __u32 pending; + int cpu; /* * Mask out PF_MEMALLOC s current task context is borrowed for the @@ -231,7 +265,7 @@ asmlinkage void __do_softirq(void) account_irq_enter_time(current); __local_bh_disable(_RET_IP_, SOFTIRQ_OFFSET); - lockdep_softirq_enter(); + in_hardirq = lockdep_softirq_start(); cpu = smp_processor_id(); restart: @@ -278,16 +312,13 @@ restart: wakeup_softirqd(); } - lockdep_softirq_exit(); - + lockdep_softirq_end(in_hardirq); account_irq_exit_time(current); __local_bh_enable(SOFTIRQ_OFFSET); WARN_ON_ONCE(in_interrupt()); tsk_restore_flags(current, old_flags, PF_MEMALLOC); } - - asmlinkage void do_softirq(void) { __u32 pending; @@ -375,13 +406,13 @@ void irq_exit(void) #endif account_irq_exit_time(current); - trace_hardirq_exit(); preempt_count_sub(HARDIRQ_OFFSET); if (!in_interrupt() && local_softirq_pending()) invoke_softirq(); tick_irq_exit(); rcu_irq_exit(); + trace_hardirq_exit(); /* must be last! */ } /* |