diff options
| -rw-r--r-- | Documentation/lockstat.txt | 2 | ||||
| -rw-r--r-- | drivers/char/random.c | 6 | ||||
| -rw-r--r-- | drivers/idle/i7300_idle.c | 8 | ||||
| -rw-r--r-- | drivers/usb/chipidea/debug.c | 2 | ||||
| -rw-r--r-- | fs/file.c | 2 | ||||
| -rw-r--r-- | include/asm-generic/cmpxchg-local.h | 8 | ||||
| -rw-r--r-- | include/linux/idr.h | 2 | ||||
| -rw-r--r-- | include/linux/lockdep.h | 2 | ||||
| -rw-r--r-- | include/linux/seqlock.h | 193 | ||||
| -rw-r--r-- | kernel/futex.c | 2 | ||||
| -rw-r--r-- | kernel/futex_compat.c | 2 | ||||
| -rw-r--r-- | kernel/lockdep.c | 15 | ||||
| -rw-r--r-- | kernel/time/ntp.c | 26 | ||||
| -rw-r--r-- | kernel/watchdog.c | 10 | ||||
| -rw-r--r-- | lib/locking-selftest.c | 34 | ||||
| -rw-r--r-- | lib/rwsem-spinlock.c | 69 | ||||
| -rw-r--r-- | lib/rwsem.c | 75 |
17 files changed, 221 insertions, 237 deletions
diff --git a/Documentation/lockstat.txt b/Documentation/lockstat.txt index cef00d4..dd2f7b2 100644 --- a/Documentation/lockstat.txt +++ b/Documentation/lockstat.txt @@ -65,7 +65,7 @@ that had to wait on lock acquisition. - CONFIGURATION -Lock statistics are enabled via CONFIG_LOCK_STATS. +Lock statistics are enabled via CONFIG_LOCK_STAT. - USAGE diff --git a/drivers/char/random.c b/drivers/char/random.c index 85e81ec..594bda9 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -445,7 +445,7 @@ static struct entropy_store input_pool = { .poolinfo = &poolinfo_table[0], .name = "input", .limit = 1, - .lock = __SPIN_LOCK_UNLOCKED(&input_pool.lock), + .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), .pool = input_pool_data }; @@ -454,7 +454,7 @@ static struct entropy_store blocking_pool = { .name = "blocking", .limit = 1, .pull = &input_pool, - .lock = __SPIN_LOCK_UNLOCKED(&blocking_pool.lock), + .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock), .pool = blocking_pool_data }; @@ -462,7 +462,7 @@ static struct entropy_store nonblocking_pool = { .poolinfo = &poolinfo_table[1], .name = "nonblocking", .pull = &input_pool, - .lock = __SPIN_LOCK_UNLOCKED(&nonblocking_pool.lock), + .lock = __SPIN_LOCK_UNLOCKED(nonblocking_pool.lock), .pool = nonblocking_pool_data }; diff --git a/drivers/idle/i7300_idle.c b/drivers/idle/i7300_idle.c index fa080eb..ffeebc7 100644 --- a/drivers/idle/i7300_idle.c +++ b/drivers/idle/i7300_idle.c @@ -75,7 +75,7 @@ static unsigned long past_skip; static struct pci_dev *fbd_dev; -static spinlock_t i7300_idle_lock; +static raw_spinlock_t i7300_idle_lock; static int i7300_idle_active; static u8 i7300_idle_thrtctl_saved; @@ -457,7 +457,7 @@ static int i7300_idle_notifier(struct notifier_block *nb, unsigned long val, idle_begin_time = ktime_get(); } - spin_lock_irqsave(&i7300_idle_lock, flags); + raw_spin_lock_irqsave(&i7300_idle_lock, flags); if (val == IDLE_START) { cpumask_set_cpu(smp_processor_id(), idle_cpumask); @@ -506,7 +506,7 @@ static int i7300_idle_notifier(struct notifier_block *nb, unsigned long val, } } end: - spin_unlock_irqrestore(&i7300_idle_lock, flags); + raw_spin_unlock_irqrestore(&i7300_idle_lock, flags); return 0; } @@ -548,7 +548,7 @@ struct debugfs_file_info { static int __init i7300_idle_init(void) { - spin_lock_init(&i7300_idle_lock); + raw_spin_lock_init(&i7300_idle_lock); total_us = 0; if (i7300_idle_platform_probe(&fbd_dev, &ioat_dev, forceload)) diff --git a/drivers/usb/chipidea/debug.c b/drivers/usb/chipidea/debug.c index 3bc244d..a62c4a4 100644 --- a/drivers/usb/chipidea/debug.c +++ b/drivers/usb/chipidea/debug.c @@ -222,7 +222,7 @@ static struct { } dbg_data = { .idx = 0, .tty = 0, - .lck = __RW_LOCK_UNLOCKED(lck) + .lck = __RW_LOCK_UNLOCKED(dbg_data.lck) }; /** @@ -516,7 +516,7 @@ struct files_struct init_files = { .close_on_exec = init_files.close_on_exec_init, .open_fds = init_files.open_fds_init, }, - .file_lock = __SPIN_LOCK_UNLOCKED(init_task.file_lock), + .file_lock = __SPIN_LOCK_UNLOCKED(init_files.file_lock), }; /* diff --git a/include/asm-generic/cmpxchg-local.h b/include/asm-generic/cmpxchg-local.h index 2533fdd..d8d4c89 100644 --- a/include/asm-generic/cmpxchg-local.h +++ b/include/asm-generic/cmpxchg-local.h @@ -21,7 +21,7 @@ static inline unsigned long __cmpxchg_local_generic(volatile void *ptr, if (size == 8 && sizeof(unsigned long) != 8) wrong_size_cmpxchg(ptr); - local_irq_save(flags); + raw_local_irq_save(flags); switch (size) { case 1: prev = *(u8 *)ptr; if (prev == old) @@ -42,7 +42,7 @@ static inline unsigned long __cmpxchg_local_generic(volatile void *ptr, default: wrong_size_cmpxchg(ptr); } - local_irq_restore(flags); + raw_local_irq_restore(flags); return prev; } @@ -55,11 +55,11 @@ static inline u64 __cmpxchg64_local_generic(volatile void *ptr, u64 prev; unsigned long flags; - local_irq_save(flags); + raw_local_irq_save(flags); prev = *(u64 *)ptr; if (prev == old) *(u64 *)ptr = new; - local_irq_restore(flags); + raw_local_irq_restore(flags); return prev; } diff --git a/include/linux/idr.h b/include/linux/idr.h index de7e190..e5eb125 100644 --- a/include/linux/idr.h +++ b/include/linux/idr.h @@ -136,7 +136,7 @@ struct ida { struct ida_bitmap *free_bitmap; }; -#define IDA_INIT(name) { .idr = IDR_INIT(name), .free_bitmap = NULL, } +#define IDA_INIT(name) { .idr = IDR_INIT((name).idr), .free_bitmap = NULL, } #define DEFINE_IDA(name) struct ida name = IDA_INIT(name) int ida_pre_get(struct ida *ida, gfp_t gfp_mask); diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index bfe88c4..f1e877b 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -412,7 +412,7 @@ struct lock_class_key { }; #define lockdep_depth(tsk) (0) -#define lockdep_assert_held(l) do { } while (0) +#define lockdep_assert_held(l) do { (void)(l); } while (0) #define lockdep_recursing(tsk) (0) diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 600060e2..1829905 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -30,92 +30,12 @@ #include <linux/preempt.h> #include <asm/processor.h> -typedef struct { - unsigned sequence; - spinlock_t lock; -} seqlock_t; - -/* - * These macros triggered gcc-3.x compile-time problems. We think these are - * OK now. Be cautious. - */ -#define __SEQLOCK_UNLOCKED(lockname) \ - { 0, __SPIN_LOCK_UNLOCKED(lockname) } - -#define seqlock_init(x) \ - do { \ - (x)->sequence = 0; \ - spin_lock_init(&(x)->lock); \ - } while (0) - -#define DEFINE_SEQLOCK(x) \ - seqlock_t x = __SEQLOCK_UNLOCKED(x) - -/* Lock out other writers and update the count. - * Acts like a normal spin_lock/unlock. - * Don't need preempt_disable() because that is in the spin_lock already. - */ -static inline void write_seqlock(seqlock_t *sl) -{ - spin_lock(&sl->lock); - ++sl->sequence; - smp_wmb(); -} - -static inline void write_sequnlock(seqlock_t *sl) -{ - smp_wmb(); - sl->sequence++; - spin_unlock(&sl->lock); -} - -static inline int write_tryseqlock(seqlock_t *sl) -{ - int ret = spin_trylock(&sl->lock); - - if (ret) { - ++sl->sequence; - smp_wmb(); - } - return ret; -} - -/* Start of read calculation -- fetch last complete writer token */ -static __always_inline unsigned read_seqbegin(const seqlock_t *sl) -{ - unsigned ret; - -repeat: - ret = ACCESS_ONCE(sl->sequence); - if (unlikely(ret & 1)) { - cpu_relax(); - goto repeat; - } - smp_rmb(); - - return ret; -} - -/* - * Test if reader processed invalid data. - * - * If sequence value changed then writer changed data while in section. - */ -static __always_inline int read_seqretry(const seqlock_t *sl, unsigned start) -{ - smp_rmb(); - - return unlikely(sl->sequence != start); -} - - /* * Version using sequence counter only. * This can be used when code has its own mutex protecting the * updating starting before the write_seqcountbeqin() and ending * after the write_seqcount_end(). */ - typedef struct seqcount { unsigned sequence; } seqcount_t; @@ -218,7 +138,6 @@ static inline int __read_seqcount_retry(const seqcount_t *s, unsigned start) static inline int read_seqcount_retry(const seqcount_t *s, unsigned start) { smp_rmb(); - return __read_seqcount_retry(s, start); } @@ -252,31 +171,101 @@ static inline void write_seqcount_barrier(seqcount_t *s) s->sequence+=2; } +typedef struct { + struct seqcount seqcount; + spinlock_t lock; +} seqlock_t; + /* - * Possible sw/hw IRQ protected versions of the interfaces. + * These macros triggered gcc-3.x compile-time problems. We think these are + * OK now. Be cautious. */ -#define write_seqlock_irqsave(lock, flags) \ - do { local_irq_save(flags); write_seqlock(lock); } while (0) -#define write_seqlock_irq(lock) \ - do { local_irq_disable(); write_seqlock(lock); } while (0) -#define write_seqlock_bh(lock) \ - do { local_bh_disable(); write_seqlock(lock); } while (0) +#define __SEQLOCK_UNLOCKED(lockname) \ + { \ + .seqcount = SEQCNT_ZERO, \ + .lock = __SPIN_LOCK_UNLOCKED(lockname) \ + } + +#define seqlock_init(x) \ + do { \ + seqcount_init(&(x)->seqcount); \ + spin_lock_init(&(x)->lock); \ + } while (0) -#define write_sequnlock_irqrestore(lock, flags) \ - do { write_sequnlock(lock); local_irq_restore(flags); } while(0) -#define write_sequnlock_irq(lock) \ - do { write_sequnlock(lock); local_irq_enable(); } while(0) -#define write_sequnlock_bh(lock) \ - do { write_sequnlock(lock); local_bh_enable(); } while(0) +#define DEFINE_SEQLOCK(x) \ + seqlock_t x = __SEQLOCK_UNLOCKED(x) -#define read_seqbegin_irqsave(lock, flags) \ - ({ local_irq_save(flags); read_seqbegin(lock); }) +/* + * Read side functions for starting and finalizing a read side section. + */ +static inline unsigned read_seqbegin(const seqlock_t *sl) +{ + return read_seqcount_begin(&sl->seqcount); +} -#define read_seqretry_irqrestore(lock, iv, flags) \ - ({ \ - int ret = read_seqretry(lock, iv); \ - local_irq_restore(flags); \ - ret; \ - }) +static inline unsigned read_seqretry(const seqlock_t *sl, unsigned start) +{ + return read_seqcount_retry(&sl->seqcount, start); +} + +/* + * Lock out other writers and update the count. + * Acts like a normal spin_lock/unlock. + * Don't need preempt_disable() because that is in the spin_lock already. + */ +static inline void write_seqlock(seqlock_t *sl) +{ + spin_lock(&sl->lock); + write_seqcount_begin(&sl->seqcount); +} + +static inline void write_sequnlock(seqlock_t *sl) +{ + write_seqcount_end(&sl->seqcount); + spin_unlock(&sl->lock); +} + +static inline void write_seqlock_bh(seqlock_t *sl) +{ + spin_lock_bh(&sl->lock); + write_seqcount_begin(&sl->seqcount); +} + +static inline void write_sequnlock_bh(seqlock_t *sl) +{ + write_seqcount_end(&sl->seqcount); + spin_unlock_bh(&sl->lock); +} + +static inline void write_seqlock_irq(seqlock_t *sl) +{ + spin_lock_irq(&sl->lock); + write_seqcount_begin(&sl->seqcount); +} + +static inline void write_sequnlock_irq(seqlock_t *sl) +{ + write_seqcount_end(&sl->seqcount); + spin_unlock_irq(&sl->lock); +} + +static inline unsigned long __write_seqlock_irqsave(seqlock_t *sl) +{ + unsigned long flags; + + spin_lock_irqsave(&sl->lock, flags); + write_seqcount_begin(&sl->seqcount); + return flags; +} + +#define write_seqlock_irqsave(lock, flags) \ + do { flags = __write_seqlock_irqsave(lock); } while (0) + +static inline void +write_sequnlock_irqrestore(seqlock_t *sl, unsigned long flags) +{ + write_seqcount_end(&sl->seqcount); + spin_unlock_irqrestore(&sl->lock, flags); +} #endif /* __LINUX_SEQLOCK_H */ diff --git a/kernel/futex.c b/kernel/futex.c index 9618b6e..fbc07a2 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -2472,8 +2472,6 @@ SYSCALL_DEFINE3(get_robust_list, int, pid, if (!futex_cmpxchg_enabled) return -ENOSYS; - WARN_ONCE(1, "deprecated: get_robust_list will be deleted in 2013.\n"); - rcu_read_lock(); ret = -ESRCH; diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c index 83e368b..a9642d5 100644 --- a/kernel/futex_compat.c +++ b/kernel/futex_compat.c @@ -142,8 +142,6 @@ compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr, if (!futex_cmpxchg_enabled) return -ENOSYS; - WARN_ONCE(1, "deprecated: get_robust_list will be deleted in 2013.\n"); - rcu_read_lock(); ret = -ESRCH; diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 7981e5b..8a0efac 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -3190,9 +3190,14 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, #endif if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { debug_locks_off(); - printk("BUG: MAX_LOCK_DEPTH too low!\n"); + printk("BUG: MAX_LOCK_DEPTH too low, depth: %i max: %lu!\n", + curr->lockdep_depth, MAX_LOCK_DEPTH); printk("turning off the locking correctness validator.\n"); + + lockdep_print_held_locks(current); + debug_show_all_locks(); dump_stack(); + return 0; } @@ -3203,7 +3208,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, } static int -print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock, +print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock, unsigned long ip) { if (!debug_locks_off()) @@ -3246,7 +3251,7 @@ static int check_unlock(struct task_struct *curr, struct lockdep_map *lock, return 0; if (curr->lockdep_depth <= 0) - return print_unlock_inbalance_bug(curr, lock, ip); + return print_unlock_imbalance_bug(curr, lock, ip); return 1; } @@ -3317,7 +3322,7 @@ __lock_set_class(struct lockdep_map *lock, const char *name, goto found_it; prev_hlock = hlock; } - return print_unlock_inbalance_bug(curr, lock, ip); + return print_unlock_imbalance_bug(curr, lock, ip); found_it: lockdep_init_map(lock, name, key, 0); @@ -3384,7 +3389,7 @@ lock_release_non_nested(struct task_struct *curr, goto found_it; prev_hlock = hlock; } - return print_unlock_inbalance_bug(curr, lock, ip); + return print_unlock_imbalance_bug(curr, lock, ip); found_it: if (hlock->instance == lock) diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index b10a42b..072bb06 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -23,7 +23,7 @@ * NTP timekeeping variables: */ -DEFINE_SPINLOCK(ntp_lock); +DEFINE_RAW_SPINLOCK(ntp_lock); /* USER_HZ period (usecs): */ @@ -348,7 +348,7 @@ void ntp_clear(void) { unsigned long flags; - spin_lock_irqsave(&ntp_lock, flags); + raw_spin_lock_irqsave(&ntp_lock, flags); time_adjust = 0; /* stop active adjtime() */ time_status |= STA_UNSYNC; @@ -362,7 +362,7 @@ void ntp_clear(void) /* Clear PPS state variables */ pps_clear(); - spin_unlock_irqrestore(&ntp_lock, flags); + raw_spin_unlock_irqrestore(&ntp_lock, flags); } @@ -372,9 +372,9 @@ u64 ntp_tick_length(void) unsigned long flags; s64 ret; - spin_lock_irqsave(&ntp_lock, flags); + raw_spin_lock_irqsave(&ntp_lock, flags); ret = tick_length; - spin_unlock_irqrestore(&ntp_lock, flags); + raw_spin_unlock_irqrestore(&ntp_lock, flags); return ret; } @@ -395,7 +395,7 @@ int second_overflow(unsigned long secs) int leap = 0; unsigned long flags; - spin_lock_irqsave(&ntp_lock, flags); + raw_spin_lock_irqsave(&ntp_lock, flags); /* * Leap second processing. If in leap-insert state at the end of the @@ -479,7 +479,7 @@ int second_overflow(unsigned long secs) time_adjust = 0; out: - spin_unlock_irqrestore(&ntp_lock, flags); + raw_spin_unlock_irqrestore(&ntp_lock, flags); return leap; } @@ -672,7 +672,7 @@ int do_adjtimex(struct timex *txc) getnstimeofday(&ts); - spin_lock_irq(&ntp_lock); + raw_spin_lock_irq(&ntp_lock); if (txc->modes & ADJ_ADJTIME) { long save_adjust = time_adjust; @@ -714,7 +714,7 @@ int do_adjtimex(struct timex *txc) /* fill PPS status fields */ pps_fill_timex(txc); - spin_unlock_irq(&ntp_lock); + raw_spin_unlock_irq(&ntp_lock); txc->time.tv_sec = ts.tv_sec; txc->time.tv_usec = ts.tv_nsec; @@ -912,7 +912,7 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts) pts_norm = pps_normalize_ts(*phase_ts); - spin_lock_irqsave(&ntp_lock, flags); + raw_spin_lock_irqsave(&ntp_lock, flags); /* clear the error bits, they will be set again if needed */ time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR); @@ -925,7 +925,7 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts) * just start the frequency interval */ if (unlikely(pps_fbase.tv_sec == 0)) { pps_fbase = *raw_ts; - spin_unlock_irqrestore(&ntp_lock, flags); + raw_spin_unlock_irqrestore(&ntp_lock, flags); return; } @@ -940,7 +940,7 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts) time_status |= STA_PPSJITTER; /* restart the frequency calibration interval */ pps_fbase = *raw_ts; - spin_unlock_irqrestore(&ntp_lock, flags); + raw_spin_unlock_irqrestore(&ntp_lock, flags); pr_err("hardpps: PPSJITTER: bad pulse\n"); return; } @@ -957,7 +957,7 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts) hardpps_update_phase(pts_norm.nsec); - spin_unlock_irqrestore(&ntp_lock, flags); + raw_spin_unlock_irqrestore(&ntp_lock, flags); } EXPORT_SYMBOL(hardpps); diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 2768942..4a94467 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -113,9 +113,9 @@ static int get_softlockup_thresh(void) * resolution, and we don't need to waste time with a big divide when * 2^30ns == 1.074s. */ -static unsigned long get_timestamp(int this_cpu) +static unsigned long get_timestamp(void) { - return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */ + return local_clock() >> 30LL; /* 2^30 ~= 10^9 */ } static void set_sample_period(void) @@ -133,9 +133,7 @@ static void set_sample_period(void) /* Commands for resetting the watchdog */ static void __touch_watchdog(void) { - int this_cpu = smp_processor_id(); - - __this_cpu_write(watchdog_touch_ts, get_timestamp(this_cpu)); + __this_cpu_write(watchdog_touch_ts, get_timestamp()); } void touch_softlockup_watchdog(void) @@ -196,7 +194,7 @@ static int is_hardlockup(void) static int is_softlockup(unsigned long touch_ts) { - unsigned long now = get_timestamp(smp_processor_id()); + unsigned long now = get_timestamp(); /* Warn about unreasonable delays: */ if (time_after(now, touch_ts + get_softlockup_thresh())) diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c index 7aae0f2..c3eb261 100644 --- a/lib/locking-selftest.c +++ b/lib/locking-selftest.c @@ -47,10 +47,10 @@ __setup("debug_locks_verbose=", setup_debug_locks_verbose); * Normal standalone locks, for the circular and irq-context * dependency tests: */ -static DEFINE_SPINLOCK(lock_A); -static DEFINE_SPINLOCK(lock_B); -static DEFINE_SPINLOCK(lock_C); -static DEFINE_SPINLOCK(lock_D); +static DEFINE_RAW_SPINLOCK(lock_A); +static DEFINE_RAW_SPINLOCK(lock_B); +static DEFINE_RAW_SPINLOCK(lock_C); +static DEFINE_RAW_SPINLOCK(lock_D); static DEFINE_RWLOCK(rwlock_A); static DEFINE_RWLOCK(rwlock_B); @@ -73,12 +73,12 @@ static DECLARE_RWSEM(rwsem_D); * but X* and Y* are different classes. We do this so that * we do not trigger a real lockup: */ -static DEFINE_SPINLOCK(lock_X1); -static DEFINE_SPINLOCK(lock_X2); -static DEFINE_SPINLOCK(lock_Y1); -static DEFINE_SPINLOCK(lock_Y2); -static DEFINE_SPINLOCK(lock_Z1); -static DEFINE_SPINLOCK(lock_Z2); +static DEFINE_RAW_SPINLOCK(lock_X1); +static DEFINE_RAW_SPINLOCK(lock_X2); +static DEFINE_RAW_SPINLOCK(lock_Y1); +static DEFINE_RAW_SPINLOCK(lock_Y2); +static DEFINE_RAW_SPINLOCK(lock_Z1); +static DEFINE_RAW_SPINLOCK(lock_Z2); static DEFINE_RWLOCK(rwlock_X1); static DEFINE_RWLOCK(rwlock_X2); @@ -107,10 +107,10 @@ static DECLARE_RWSEM(rwsem_Z2); */ #define INIT_CLASS_FUNC(class) \ static noinline void \ -init_class_##class(spinlock_t *lock, rwlock_t *rwlock, struct mutex *mutex, \ - struct rw_semaphore *rwsem) \ +init_class_##class(raw_spinlock_t *lock, rwlock_t *rwlock, \ + struct mutex *mutex, struct rw_semaphore *rwsem)\ { \ - spin_lock_init(lock); \ + raw_spin_lock_init(lock); \ rwlock_init(rwlock); \ mutex_init(mutex); \ init_rwsem(rwsem); \ @@ -168,10 +168,10 @@ static void init_shared_classes(void) * Shortcuts for lock/unlock API variants, to keep * the testcases compact: */ -#define L(x) spin_lock(&lock_##x) -#define U(x) spin_unlock(&lock_##x) +#define L(x) raw_spin_lock(&lock_##x) +#define U(x) raw_spin_unlock(&lock_##x) #define LU(x) L(x); U(x) -#define SI(x) spin_lock_init(&lock_##x) +#define SI(x) raw_spin_lock_init(&lock_##x) #define WL(x) write_lock(&rwlock_##x) #define WU(x) write_unlock(&rwlock_##x) @@ -911,7 +911,7 @@ GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion_soft) #define I2(x) \ do { \ - spin_lock_init(&lock_##x); \ + raw_spin_lock_init(&lock_##x); \ rwlock_init(&rwlock_##x); \ mutex_init(&mutex_##x); \ init_rwsem(&rwsem_##x); \ diff --git a/lib/rwsem-spinlock.c b/lib/rwsem-spinlock.c index 7e0d6a5..7542afb 100644 --- a/lib/rwsem-spinlock.c +++ b/lib/rwsem-spinlock.c @@ -73,20 +73,13 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite) goto dont_wake_writers; } - /* if we are allowed to wake writers try to grant a single write lock - * if there's a writer at the front of the queue - * - we leave the 'waiting count' incremented to signify potential - * contention + /* + * as we support write lock stealing, we can't set sem->activity + * to -1 here to indicate we get the lock. Instead, we wake it up + * to let it go get it again. */ if (waiter->flags & RWSEM_WAITING_FOR_WRITE) { - sem->activity = -1; - list_del(&waiter->list); - tsk = waiter->task; - /* Don't touch waiter after ->task has been NULLed */ - smp_mb(); - waiter->task = NULL; - wake_up_process(tsk); - put_task_struct(tsk); + wake_up_process(waiter->task); goto out; } @@ -121,18 +114,10 @@ static inline struct rw_semaphore * __rwsem_wake_one_writer(struct rw_semaphore *sem) { struct rwsem_waiter *waiter; - struct task_struct *tsk; - - sem->activity = -1; waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list); - list_del(&waiter->list); + wake_up_process(waiter->task); - tsk = waiter->task; - smp_mb(); - waiter->task = NULL; - wake_up_process(tsk); - put_task_struct(tsk); return sem; } @@ -204,7 +189,6 @@ int __down_read_trylock(struct rw_semaphore *sem) /* * get a write lock on the semaphore - * - we increment the waiting count anyway to indicate an exclusive lock */ void __sched __down_write_nested(struct rw_semaphore *sem, int subclass) { @@ -214,37 +198,32 @@ void __sched __down_write_nested(struct rw_semaphore *sem, int subclass) raw_spin_lock_irqsave(&sem->wait_lock, flags); - if (sem->activity == 0 && list_empty(&sem->wait_list)) { - /* granted */ - sem->activity = -1; - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - goto out; - } - - tsk = current; - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - /* set up my own style of waitqueue */ + tsk = current; waiter.task = tsk; waiter.flags = RWSEM_WAITING_FOR_WRITE; - get_task_struct(tsk); - list_add_tail(&waiter.list, &sem->wait_list); - /* we don't need to touch the semaphore struct anymore */ - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - - /* wait to be given the lock */ + /* wait for someone to release the lock */ for (;;) { - if (!waiter.task) + /* + * That is the key to support write lock stealing: allows the + * task already on CPU to get the lock soon rather than put + * itself into sleep and waiting for system woke it or someone + * else in the head of the wait list up. + */ + if (sem->activity == 0) break; - schedule(); set_task_state(tsk, TASK_UNINTERRUPTIBLE); + raw_spin_unlock_irqrestore(&sem->wait_lock, flags); + schedule(); + raw_spin_lock_irqsave(&sem->wait_lock, flags); } + /* got the lock */ + sem->activity = -1; + list_del(&waiter.list); - tsk->state = TASK_RUNNING; - out: - ; + raw_spin_unlock_irqrestore(&sem->wait_lock, flags); } void __sched __down_write(struct rw_semaphore *sem) @@ -262,8 +241,8 @@ int __down_write_trylock(struct rw_semaphore *sem) raw_spin_lock_irqsave(&sem->wait_lock, flags); - if (sem->activity == 0 && list_empty(&sem->wait_list)) { - /* granted */ + if (sem->activity == 0) { + /* got the lock */ sem->activity = -1; ret = 1; } diff --git a/lib/rwsem.c b/lib/rwsem.c index 8337e1b9b..ad5e0df 100644 --- a/lib/rwsem.c +++ b/lib/rwsem.c @@ -2,6 +2,8 @@ * * Written by David Howells (dhowells@redhat.com). * Derived from arch/i386/kernel/semaphore.c + * + * Writer lock-stealing by Alex Shi <alex.shi@intel.com> */ #include <linux/rwsem.h> #include <linux/sched.h> @@ -60,7 +62,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wake_type) struct rwsem_waiter *waiter; struct task_struct *tsk; struct list_head *next; - signed long oldcount, woken, loop, adjustment; + signed long woken, loop, adjustment; waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list); if (!(waiter->flags & RWSEM_WAITING_FOR_WRITE)) @@ -72,30 +74,8 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wake_type) */ goto out; - /* There's a writer at the front of the queue - try to grant it the - * write lock. However, we only wake this writer if we can transition - * the active part of the count from 0 -> 1 - */ - adjustment = RWSEM_ACTIVE_WRITE_BIAS; - if (waiter->list.next == &sem->wait_list) - adjustment -= RWSEM_WAITING_BIAS; - - try_again_write: - oldcount = rwsem_atomic_update(adjustment, sem) - adjustment; - if (oldcount & RWSEM_ACTIVE_MASK) - /* Someone grabbed the sem already */ - goto undo_write; - - /* We must be careful not to touch 'waiter' after we set ->task = NULL. - * It is an allocated on the waiter's stack and may become invalid at - * any time after that point (due to a wakeup from another source). - */ - list_del(&waiter->list); - tsk = waiter->task; - smp_mb(); - waiter->task = NULL; - wake_up_process(tsk); - put_task_struct(tsk); + /* Wake up the writing waiter and let the task grab the sem: */ + wake_up_process(waiter->task); goto out; readers_only: @@ -157,12 +137,40 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wake_type) out: return sem; +} + +/* Try to get write sem, caller holds sem->wait_lock: */ +static int try_get_writer_sem(struct rw_semaphore *sem, + struct rwsem_waiter *waiter) +{ + struct rwsem_waiter *fwaiter; + long oldcount, adjustment; - /* undo the change to the active count, but check for a transition - * 1->0 */ - undo_write: + /* only steal when first waiter is writing */ + fwaiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list); + if (!(fwaiter->flags & RWSEM_WAITING_FOR_WRITE)) + return 0; + + adjustment = RWSEM_ACTIVE_WRITE_BIAS; + /* Only one waiter in the queue: */ + if (fwaiter == waiter && waiter->list.next == &sem->wait_list) + adjustment -= RWSEM_WAITING_BIAS; + +try_again_write: + oldcount = rwsem_atomic_update(adjustment, sem) - adjustment; + if (!(oldcount & RWSEM_ACTIVE_MASK)) { + /* No active lock: */ + struct task_struct *tsk = waiter->task; + + list_del(&waiter->list); + smp_mb(); + put_task_struct(tsk); + tsk->state = TASK_RUNNING; + return 1; + } + /* some one grabbed the sem already */ if (rwsem_atomic_update(-adjustment, sem) & RWSEM_ACTIVE_MASK) - goto out; + return 0; goto try_again_write; } @@ -210,6 +218,15 @@ rwsem_down_failed_common(struct rw_semaphore *sem, for (;;) { if (!waiter.task) break; + + raw_spin_lock_irq(&sem->wait_lock); + /* Try to get the writer sem, may steal from the head writer: */ + if (flags == RWSEM_WAITING_FOR_WRITE) + if (try_get_writer_sem(sem, &waiter)) { + raw_spin_unlock_irq(&sem->wait_lock); + return sem; + } + raw_spin_unlock_irq(&sem->wait_lock); schedule(); set_task_state(tsk, TASK_UNINTERRUPTIBLE); } |
