diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/posix-timers.c | 106 |
1 files changed, 69 insertions, 37 deletions
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 2a2e173d0a7a..34d75926b843 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -40,38 +40,31 @@ #include <linux/list.h> #include <linux/init.h> #include <linux/compiler.h> -#include <linux/idr.h> +#include <linux/hash.h> #include <linux/posix-clock.h> #include <linux/posix-timers.h> #include <linux/syscalls.h> #include <linux/wait.h> #include <linux/workqueue.h> #include <linux/export.h> +#include <linux/hashtable.h> /* - * Management arrays for POSIX timers. Timers are kept in slab memory - * Timer ids are allocated by an external routine that keeps track of the - * id and the timer. The external interface is: - * - * void *idr_find(struct idr *idp, int id); to find timer_id <id> - * int idr_get_new(struct idr *idp, void *ptr); to get a new id and - * related it to <ptr> - * void idr_remove(struct idr *idp, int id); to release <id> - * void idr_init(struct idr *idp); to initialize <idp> - * which we supply. - * The idr_get_new *may* call slab for more memory so it must not be - * called under a spin lock. Likewise idr_remore may release memory - * (but it may be ok to do this under a lock...). - * idr_find is just a memory look up and is quite fast. A -1 return - * indicates that the requested id does not exist. + * Management arrays for POSIX timers. Timers are now kept in static hash table + * with 512 entries. + * Timer ids are allocated by local routine, which selects proper hash head by + * key, constructed from current->signal address and per signal struct counter. + * This keeps timer ids unique per process, but now they can intersect between + * processes. */ /* * Lets keep our timers in a slab cache :-) */ static struct kmem_cache *posix_timers_cache; -static struct idr posix_timers_id; -static DEFINE_SPINLOCK(idr_lock); + +static DEFINE_HASHTABLE(posix_timers_hashtable, 9); +static DEFINE_SPINLOCK(hash_lock); /* * we assume that the new SIGEV_THREAD_ID shares no bits with the other @@ -152,6 +145,57 @@ static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags); __timr; \ }) +static int hash(struct signal_struct *sig, unsigned int nr) +{ + return hash_32(hash32_ptr(sig) ^ nr, HASH_BITS(posix_timers_hashtable)); +} + +static struct k_itimer *__posix_timers_find(struct hlist_head *head, + struct signal_struct *sig, + timer_t id) +{ + struct hlist_node *node; + struct k_itimer *timer; + + hlist_for_each_entry_rcu(timer, head, t_hash) { + if ((timer->it_signal == sig) && (timer->it_id == id)) + return timer; + } + return NULL; +} + +static struct k_itimer *posix_timer_by_id(timer_t id) +{ + struct signal_struct *sig = current->signal; + struct hlist_head *head = &posix_timers_hashtable[hash(sig, id)]; + + return __posix_timers_find(head, sig, id); +} + +static int posix_timer_add(struct k_itimer *timer) +{ + struct signal_struct *sig = current->signal; + int first_free_id = sig->posix_timer_id; + struct hlist_head *head; + int ret = -ENOENT; + + do { + spin_lock(&hash_lock); + head = &posix_timers_hashtable[hash(sig, sig->posix_timer_id)]; + if (!__posix_timers_find(head, sig, sig->posix_timer_id)) { + hlist_add_head_rcu(&timer->t_hash, head); + ret = sig->posix_timer_id; + } + if (++sig->posix_timer_id < 0) + sig->posix_timer_id = 0; + if ((sig->posix_timer_id == first_free_id) && (ret == -ENOENT)) + /* Loop over all possible ids completed */ + ret = -EAGAIN; + spin_unlock(&hash_lock); + } while (ret == -ENOENT); + return ret; +} + static inline void unlock_timer(struct k_itimer *timr, unsigned long flags) { spin_unlock_irqrestore(&timr->it_lock, flags); @@ -298,7 +342,6 @@ static __init int init_posix_timers(void) posix_timers_cache = kmem_cache_create("posix_timers_cache", sizeof (struct k_itimer), 0, SLAB_PANIC, NULL); - idr_init(&posix_timers_id); return 0; } @@ -520,9 +563,9 @@ static void release_posix_timer(struct k_itimer *tmr, int it_id_set) { if (it_id_set) { unsigned long flags; - spin_lock_irqsave(&idr_lock, flags); - idr_remove(&posix_timers_id, tmr->it_id); - spin_unlock_irqrestore(&idr_lock, flags); + spin_lock_irqsave(&hash_lock, flags); + hlist_del_rcu(&tmr->t_hash); + spin_unlock_irqrestore(&hash_lock, flags); } put_pid(tmr->it_pid); sigqueue_free(tmr->sigq); @@ -568,22 +611,11 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock, return -EAGAIN; spin_lock_init(&new_timer->it_lock); - - idr_preload(GFP_KERNEL); - spin_lock_irq(&idr_lock); - error = idr_alloc(&posix_timers_id, new_timer, 0, 0, GFP_NOWAIT); - spin_unlock_irq(&idr_lock); - idr_preload_end(); - if (error < 0) { - /* - * Weird looking, but we return EAGAIN if the IDR is - * full (proper POSIX return value for this) - */ - if (error == -ENOSPC) - error = -EAGAIN; + new_timer_id = posix_timer_add(new_timer); + if (new_timer_id < 0) { + error = new_timer_id; goto out; } - new_timer_id = error; it_id_set = IT_ID_SET; new_timer->it_id = (timer_t) new_timer_id; @@ -661,7 +693,7 @@ static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags) return NULL; rcu_read_lock(); - timr = idr_find(&posix_timers_id, (int)timer_id); + timr = posix_timer_by_id(timer_id); if (timr) { spin_lock_irqsave(&timr->it_lock, *flags); if (timr->it_signal == current->signal) { |