From 2da8c8bc44b572cbf623629ff736608dc7968436 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Tue, 7 Jun 2011 22:53:39 +0200 Subject: sched: Remove pointless in_atomic() definition check It's really supposed to be defined here. If it's not then we actually want the build to crash so that we know it, and not keep it silent. Signed-off-by: Frederic Weisbecker Cc: Ingo Molnar Cc: Peter Zijlstra --- kernel/sched.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index fd18f395a1bf..01d9536aaa8e 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -8028,7 +8028,6 @@ static inline int preempt_count_equals(int preempt_offset) void __might_sleep(const char *file, int line, int preempt_offset) { -#ifdef in_atomic static unsigned long prev_jiffy; /* ratelimiting */ if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) || @@ -8050,7 +8049,6 @@ void __might_sleep(const char *file, int line, int preempt_offset) if (irqs_disabled()) print_irqtrace_events(current); dump_stack(); -#endif } EXPORT_SYMBOL(__might_sleep); #endif -- cgit v1.2.3 From bdd4e85dc36cdbcfc1608a5b2a17c80a9db8986a Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 8 Jun 2011 01:13:27 +0200 Subject: sched: Isolate preempt counting in its own config option Create a new CONFIG_PREEMPT_COUNT that handles the inc/dec of preempt count offset independently. So that the offset can be updated by preempt_disable() and preempt_enable() even without the need for CONFIG_PREEMPT beeing set. This prepares to make CONFIG_DEBUG_SPINLOCK_SLEEP working with !CONFIG_PREEMPT where it currently doesn't detect code that sleeps inside explicit preemption disabled sections. Signed-off-by: Frederic Weisbecker Acked-by: Paul E. McKenney Cc: Ingo Molnar Cc: Peter Zijlstra --- include/linux/bit_spinlock.h | 2 +- include/linux/hardirq.h | 4 ++-- include/linux/pagemap.h | 4 ++-- include/linux/preempt.h | 26 +++++++++++++++++--------- include/linux/rcupdate.h | 12 ++++++------ include/linux/sched.h | 2 +- kernel/Kconfig.preempt | 3 +++ kernel/sched.c | 2 +- 8 files changed, 33 insertions(+), 22 deletions(-) diff --git a/include/linux/bit_spinlock.h b/include/linux/bit_spinlock.h index b4326bfa684f..564d997e2168 100644 --- a/include/linux/bit_spinlock.h +++ b/include/linux/bit_spinlock.h @@ -88,7 +88,7 @@ static inline int bit_spin_is_locked(int bitnum, unsigned long *addr) { #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) return test_bit(bitnum, addr); -#elif defined CONFIG_PREEMPT +#elif defined CONFIG_PREEMPT_COUNT return preempt_count(); #else return 1; diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index ba362171e8ae..f743883f769e 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -93,7 +93,7 @@ */ #define in_nmi() (preempt_count() & NMI_MASK) -#if defined(CONFIG_PREEMPT) +#if defined(CONFIG_PREEMPT_COUNT) # define PREEMPT_CHECK_OFFSET 1 #else # define PREEMPT_CHECK_OFFSET 0 @@ -115,7 +115,7 @@ #define in_atomic_preempt_off() \ ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET) -#ifdef CONFIG_PREEMPT +#ifdef CONFIG_PREEMPT_COUNT # define preemptible() (preempt_count() == 0 && !irqs_disabled()) # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1) #else diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 716875e53520..8e38d4c140ff 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -134,7 +134,7 @@ static inline int page_cache_get_speculative(struct page *page) VM_BUG_ON(in_interrupt()); #if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU) -# ifdef CONFIG_PREEMPT +# ifdef CONFIG_PREEMPT_COUNT VM_BUG_ON(!in_atomic()); # endif /* @@ -172,7 +172,7 @@ static inline int page_cache_add_speculative(struct page *page, int count) VM_BUG_ON(in_interrupt()); #if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU) -# ifdef CONFIG_PREEMPT +# ifdef CONFIG_PREEMPT_COUNT VM_BUG_ON(!in_atomic()); # endif VM_BUG_ON(page_count(page) == 0); diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 2e681d9555bd..58969b2a8a82 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -27,6 +27,21 @@ asmlinkage void preempt_schedule(void); +#define preempt_check_resched() \ +do { \ + if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \ + preempt_schedule(); \ +} while (0) + +#else /* !CONFIG_PREEMPT */ + +#define preempt_check_resched() do { } while (0) + +#endif /* CONFIG_PREEMPT */ + + +#ifdef CONFIG_PREEMPT_COUNT + #define preempt_disable() \ do { \ inc_preempt_count(); \ @@ -39,12 +54,6 @@ do { \ dec_preempt_count(); \ } while (0) -#define preempt_check_resched() \ -do { \ - if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \ - preempt_schedule(); \ -} while (0) - #define preempt_enable() \ do { \ preempt_enable_no_resched(); \ @@ -80,18 +89,17 @@ do { \ preempt_check_resched(); \ } while (0) -#else +#else /* !CONFIG_PREEMPT_COUNT */ #define preempt_disable() do { } while (0) #define preempt_enable_no_resched() do { } while (0) #define preempt_enable() do { } while (0) -#define preempt_check_resched() do { } while (0) #define preempt_disable_notrace() do { } while (0) #define preempt_enable_no_resched_notrace() do { } while (0) #define preempt_enable_notrace() do { } while (0) -#endif +#endif /* CONFIG_PREEMPT_COUNT */ #ifdef CONFIG_PREEMPT_NOTIFIERS diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 99f9aa7c2804..8f4f881a0ad8 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -239,7 +239,7 @@ extern int rcu_read_lock_bh_held(void); * Check debug_lockdep_rcu_enabled() to prevent false positives during boot * and while lockdep is disabled. */ -#ifdef CONFIG_PREEMPT +#ifdef CONFIG_PREEMPT_COUNT static inline int rcu_read_lock_sched_held(void) { int lockdep_opinion = 0; @@ -250,12 +250,12 @@ static inline int rcu_read_lock_sched_held(void) lockdep_opinion = lock_is_held(&rcu_sched_lock_map); return lockdep_opinion || preempt_count() != 0 || irqs_disabled(); } -#else /* #ifdef CONFIG_PREEMPT */ +#else /* #ifdef CONFIG_PREEMPT_COUNT */ static inline int rcu_read_lock_sched_held(void) { return 1; } -#endif /* #else #ifdef CONFIG_PREEMPT */ +#endif /* #else #ifdef CONFIG_PREEMPT_COUNT */ #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ @@ -276,17 +276,17 @@ static inline int rcu_read_lock_bh_held(void) return 1; } -#ifdef CONFIG_PREEMPT +#ifdef CONFIG_PREEMPT_COUNT static inline int rcu_read_lock_sched_held(void) { return preempt_count() != 0 || irqs_disabled(); } -#else /* #ifdef CONFIG_PREEMPT */ +#else /* #ifdef CONFIG_PREEMPT_COUNT */ static inline int rcu_read_lock_sched_held(void) { return 1; } -#endif /* #else #ifdef CONFIG_PREEMPT */ +#endif /* #else #ifdef CONFIG_PREEMPT_COUNT */ #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ diff --git a/include/linux/sched.h b/include/linux/sched.h index 483c1ed5bc4d..4ecd5cbe7e24 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2502,7 +2502,7 @@ extern int _cond_resched(void); extern int __cond_resched_lock(spinlock_t *lock); -#ifdef CONFIG_PREEMPT +#ifdef CONFIG_PREEMPT_COUNT #define PREEMPT_LOCK_OFFSET PREEMPT_OFFSET #else #define PREEMPT_LOCK_OFFSET 0 diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt index bf987b95b356..24e7cb0ba26a 100644 --- a/kernel/Kconfig.preempt +++ b/kernel/Kconfig.preempt @@ -35,6 +35,7 @@ config PREEMPT_VOLUNTARY config PREEMPT bool "Preemptible Kernel (Low-Latency Desktop)" + select PREEMPT_COUNT help This option reduces the latency of the kernel by making all kernel code (that is not executing in a critical section) @@ -52,3 +53,5 @@ config PREEMPT endchoice +config PREEMPT_COUNT + bool \ No newline at end of file diff --git a/kernel/sched.c b/kernel/sched.c index 01d9536aaa8e..90ad7cf2b290 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2843,7 +2843,7 @@ void sched_fork(struct task_struct *p) #if defined(CONFIG_SMP) p->on_cpu = 0; #endif -#ifdef CONFIG_PREEMPT +#ifdef CONFIG_PREEMPT_COUNT /* Want to start with kernel preemption disabled. */ task_thread_info(p)->preempt_count = 1; #endif -- cgit v1.2.3 From e8f7c70f44f75c827c04239b0ae5f0068b65b76e Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 8 Jun 2011 01:51:02 +0200 Subject: sched: Make sleeping inside spinlock detection working in !CONFIG_PREEMPT Select CONFIG_PREEMPT_COUNT when we enable the sleeping inside spinlock detection, so that the preempt offset gets correctly incremented/decremented from preempt_disable()/preempt_enable(). This makes the preempt count eventually working in !CONFIG_PREEMPT when that debug option is set and thus fixes the detection of explicit preemption disabled sections under such config. Code that sleeps in explicitly preempt disabled section can be finally spotted in non-preemptible kernels. Signed-off-by: Frederic Weisbecker Acked-by: Paul E. McKenney Cc: Ingo Molnar Cc: Peter Zijlstra --- lib/Kconfig.debug | 1 + 1 file changed, 1 insertion(+) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 28afa4c5333c..a7dd7b547fea 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -650,6 +650,7 @@ config TRACE_IRQFLAGS config DEBUG_SPINLOCK_SLEEP bool "Spinlock debugging: sleep-inside-spinlock checking" + select PREEMPT_COUNT depends on DEBUG_KERNEL help If you say Y here, various routines which may sleep will become very -- cgit v1.2.3 From d902db1eb60387040fe541573083e47469db50ac Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 8 Jun 2011 19:31:56 +0200 Subject: sched: Generalize sleep inside spinlock detection The sleeping inside spinlock detection is actually used for more general sleeping inside atomic sections debugging: preemption disabled, rcu read side critical sections, interrupts, interrupt disabled, etc... Change the name of the config and its help section to reflect its more general role. Signed-off-by: Frederic Weisbecker Acked-by: Paul E. McKenney Acked-by: Randy Dunlap Cc: Peter Zijlstra Cc: Ingo Molnar --- Documentation/DocBook/kernel-hacking.tmpl | 2 +- Documentation/SubmitChecklist | 2 +- Documentation/development-process/4.Coding | 2 +- Documentation/ja_JP/SubmitChecklist | 2 +- Documentation/zh_CN/SubmitChecklist | 2 +- include/linux/kernel.h | 2 +- kernel/sched.c | 2 +- lib/Kconfig.debug | 8 +++++--- 8 files changed, 12 insertions(+), 10 deletions(-) diff --git a/Documentation/DocBook/kernel-hacking.tmpl b/Documentation/DocBook/kernel-hacking.tmpl index 7b3f49363413..07a9c48de5a2 100644 --- a/Documentation/DocBook/kernel-hacking.tmpl +++ b/Documentation/DocBook/kernel-hacking.tmpl @@ -409,7 +409,7 @@ cond_resched(); /* Will sleep */ You should always compile your kernel - CONFIG_DEBUG_SPINLOCK_SLEEP on, and it will warn + CONFIG_DEBUG_ATOMIC_SLEEP on, and it will warn you if you break these rules. If you do break the rules, you will eventually lock up your box. diff --git a/Documentation/SubmitChecklist b/Documentation/SubmitChecklist index da0382daa395..7b13be41c085 100644 --- a/Documentation/SubmitChecklist +++ b/Documentation/SubmitChecklist @@ -53,7 +53,7 @@ kernel patches. 12: Has been tested with CONFIG_PREEMPT, CONFIG_DEBUG_PREEMPT, CONFIG_DEBUG_SLAB, CONFIG_DEBUG_PAGEALLOC, CONFIG_DEBUG_MUTEXES, - CONFIG_DEBUG_SPINLOCK, CONFIG_DEBUG_SPINLOCK_SLEEP all simultaneously + CONFIG_DEBUG_SPINLOCK, CONFIG_DEBUG_ATOMIC_SLEEP all simultaneously enabled. 13: Has been build- and runtime tested with and without CONFIG_SMP and diff --git a/Documentation/development-process/4.Coding b/Documentation/development-process/4.Coding index f3f1a469443c..83f5f5b365a3 100644 --- a/Documentation/development-process/4.Coding +++ b/Documentation/development-process/4.Coding @@ -244,7 +244,7 @@ testing purposes. In particular, you should turn on: - DEBUG_SLAB can find a variety of memory allocation and use errors; it should be used on most development kernels. - - DEBUG_SPINLOCK, DEBUG_SPINLOCK_SLEEP, and DEBUG_MUTEXES will find a + - DEBUG_SPINLOCK, DEBUG_ATOMIC_SLEEP, and DEBUG_MUTEXES will find a number of common locking errors. There are quite a few other debugging options, some of which will be diff --git a/Documentation/ja_JP/SubmitChecklist b/Documentation/ja_JP/SubmitChecklist index 2df4576f1173..cb5507b1ac81 100644 --- a/Documentation/ja_JP/SubmitChecklist +++ b/Documentation/ja_JP/SubmitChecklist @@ -68,7 +68,7 @@ Linux カーネルパッチ投稿者向けチェックリスト 12: CONFIG_PREEMPT, CONFIG_DEBUG_PREEMPT, CONFIG_DEBUG_SLAB, CONFIG_DEBUG_PAGEALLOC, CONFIG_DEBUG_MUTEXES, CONFIG_DEBUG_SPINLOCK, - CONFIG_DEBUG_SPINLOCK_SLEEP これら全てを同時に有効にして動作確認を + CONFIG_DEBUG_ATOMIC_SLEEP これら全てを同時に有効にして動作確認を 行ってください。 13: CONFIG_SMP, CONFIG_PREEMPT を有効にした場合と無効にした場合の両方で diff --git a/Documentation/zh_CN/SubmitChecklist b/Documentation/zh_CN/SubmitChecklist index 951415bbab0c..4c741d6bc048 100644 --- a/Documentation/zh_CN/SubmitChecklist +++ b/Documentation/zh_CN/SubmitChecklist @@ -67,7 +67,7 @@ Linux 12ѾͨCONFIG_PREEMPT, CONFIG_DEBUG_PREEMPT, CONFIG_DEBUG_SLAB, CONFIG_DEBUG_PAGEALLOC, CONFIG_DEBUG_MUTEXES, - CONFIG_DEBUG_SPINLOCK, CONFIG_DEBUG_SPINLOCK_SLEEPԣͬʱ + CONFIG_DEBUG_SPINLOCK, CONFIG_DEBUG_ATOMIC_SLEEPԣͬʱ ʹܡ 13Ѿʹû߲ʹ CONFIG_SMP CONFIG_PREEMPTִʱ䡣 diff --git a/include/linux/kernel.h b/include/linux/kernel.h index fb0e7329fee1..24b489f66592 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -121,7 +121,7 @@ extern int _cond_resched(void); # define might_resched() do { } while (0) #endif -#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP +#ifdef CONFIG_DEBUG_ATOMIC_SLEEP void __might_sleep(const char *file, int line, int preempt_offset); /** * might_sleep - annotation for functions that can sleep diff --git a/kernel/sched.c b/kernel/sched.c index 90ad7cf2b290..a5f318b8d659 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -8018,7 +8018,7 @@ void __init sched_init(void) scheduler_running = 1; } -#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP +#ifdef CONFIG_DEBUG_ATOMIC_SLEEP static inline int preempt_count_equals(int preempt_offset) { int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth(); diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index a7dd7b547fea..81a4f3302bc8 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -648,13 +648,15 @@ config TRACE_IRQFLAGS Enables hooks to interrupt enabling and disabling for either tracing or lock debugging. -config DEBUG_SPINLOCK_SLEEP - bool "Spinlock debugging: sleep-inside-spinlock checking" +config DEBUG_ATOMIC_SLEEP + bool "Sleep inside atomic section checking" select PREEMPT_COUNT depends on DEBUG_KERNEL help If you say Y here, various routines which may sleep will become very - noisy if they are called with a spinlock held. + noisy if they are called inside atomic sections: when a spinlock is + held, inside an rcu read side critical section, inside preempt disabled + sections, inside an interrupt, etc... config DEBUG_LOCKING_API_SELFTESTS bool "Locking API boot-time self-tests" -- cgit v1.2.3