#ifndef _SPL_RWLOCK_H
-#define _SPL_RWLOCK_H
+#define _SPL_RWLOCK_H
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/rwsem.h>
#include <asm/current.h>
#include <sys/types.h>
+#include <sys/kmem.h>
-#ifdef __cplusplus
+#ifdef __cplusplus
extern "C" {
#endif
RW_READER
} krw_t;
-#define RW_READ_HELD(x) (__rw_read_held((x)))
-#define RW_WRITE_HELD(x) (__rw_write_held((x)))
-#define RW_LOCK_HELD(x) (__rw_lock_held((x)))
-#define RW_ISWRITER(x) (__rw_iswriter(x))
#define RW_MAGIC 0x3423645a
#define RW_POISON 0xa6
typedef struct {
- int rw_magic;
+ int32_t rw_magic;
+ int32_t rw_name_size;
char *rw_name;
struct rw_semaphore rw_sem;
struct task_struct *rw_owner; /* holder of the write lock */
} krwlock_t;
-#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
-struct rwsem_waiter {
- struct list_head list;
- struct task_struct *task;
- unsigned int flags;
-#define RWSEM_WAITING_FOR_READ 0x00000001
-#define RWSEM_WAITING_FOR_WRITE 0x00000002
-};
-
-/*
- * wake a single writer
- */
-static inline struct rw_semaphore *
-__rwsem_wake_one_writer_locked(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);
-
- tsk = waiter->task;
- smp_mb();
- waiter->task = NULL;
- wake_up_process(tsk);
- put_task_struct(tsk);
- return sem;
-}
-
-/*
- * release a read lock on the semaphore
- */
-static void fastcall
-__up_read_locked(struct rw_semaphore *sem)
-{
- if (--sem->activity == 0 && !list_empty(&sem->wait_list))
- sem = __rwsem_wake_one_writer_locked(sem);
-}
-
-/*
- * trylock for writing -- returns 1 if successful, 0 if contention
- */
-static int fastcall
-__down_write_trylock_locked(struct rw_semaphore *sem)
-{
- int ret = 0;
-
- if (sem->activity == 0 && list_empty(&sem->wait_list)) {
- /* granted */
- sem->activity = -1;
- ret = 1;
- }
-
- return ret;
-}
-#endif
-
+extern void __rw_init(krwlock_t *rwlp, char *name, krw_type_t type, void *arg);
+extern void __rw_destroy(krwlock_t *rwlp);
+extern int __rw_tryenter(krwlock_t *rwlp, krw_t rw);
+extern void __rw_enter(krwlock_t *rwlp, krw_t rw);
+extern void __rw_exit(krwlock_t *rwlp);
+extern void __rw_downgrade(krwlock_t *rwlp);
+extern int __rw_tryupgrade(krwlock_t *rwlp);
+extern kthread_t *__rw_owner(krwlock_t *rwlp);
extern int __rw_read_held(krwlock_t *rwlp);
extern int __rw_write_held(krwlock_t *rwlp);
extern int __rw_lock_held(krwlock_t *rwlp);
-static __inline__ void
-rw_init(krwlock_t *rwlp, char *name, krw_type_t type, void *arg)
-{
- ASSERT(type == RW_DEFAULT); /* XXX no irq handler use */
- ASSERT(arg == NULL); /* XXX no irq handler use */
-
- rwlp->rw_magic = RW_MAGIC;
- rwlp->rw_owner = NULL; /* no one holds the write lock yet */
- init_rwsem(&rwlp->rw_sem);
- rwlp->rw_name = NULL;
-
- if (name) {
- rwlp->rw_name = kmalloc(strlen(name) + 1, GFP_KERNEL);
- if (rwlp->rw_name)
- strcpy(rwlp->rw_name, name);
- }
-}
-
-static __inline__ void
-rw_destroy(krwlock_t *rwlp)
-{
- ASSERT(rwlp);
- ASSERT(rwlp->rw_magic == RW_MAGIC);
- ASSERT(rwlp->rw_owner == NULL);
- spin_lock(&rwlp->rw_sem.wait_lock);
- ASSERT(list_empty(&rwlp->rw_sem.wait_list));
- spin_unlock(&rwlp->rw_sem.wait_lock);
-
- if (rwlp->rw_name)
- kfree(rwlp->rw_name);
-
- memset(rwlp, RW_POISON, sizeof(krwlock_t));
-}
-
-/* Return 0 if the lock could not be obtained without blocking.
- */
-static __inline__ int
-rw_tryenter(krwlock_t *rwlp, krw_t rw)
-{
- int result;
-
- ASSERT(rwlp);
- ASSERT(rwlp->rw_magic == RW_MAGIC);
-
- switch (rw) {
- /* these functions return 1 if success, 0 if contention */
- case RW_READER:
- /* Here the Solaris code would return 0
- * if there were any write waiters. Specifically
- * thinking about the case where readers may have
- * the lock and we would also allow this thread
- * to grab the read lock with a writer waiting in the
- * queue. This doesn't seem like a correctness
- * issue, so just call down_read_trylock()
- * for the test. We may have to revisit this if
- * it becomes an issue */
- result = down_read_trylock(&rwlp->rw_sem);
- break;
- case RW_WRITER:
- result = down_write_trylock(&rwlp->rw_sem);
- if (result) {
- /* there better not be anyone else
- * holding the write lock here */
- ASSERT(rwlp->rw_owner == NULL);
- rwlp->rw_owner = current;
- }
- break;
- default:
- SBUG();
- }
-
- return result;
-}
-
-static __inline__ void
-rw_enter(krwlock_t *rwlp, krw_t rw)
-{
- ASSERT(rwlp);
- ASSERT(rwlp->rw_magic == RW_MAGIC);
-
- switch (rw) {
- case RW_READER:
- /* Here the Solaris code would block
- * if there were any write waiters. Specifically
- * thinking about the case where readers may have
- * the lock and we would also allow this thread
- * to grab the read lock with a writer waiting in the
- * queue. This doesn't seem like a correctness
- * issue, so just call down_read()
- * for the test. We may have to revisit this if
- * it becomes an issue */
- down_read(&rwlp->rw_sem);
- break;
- case RW_WRITER:
- down_write(&rwlp->rw_sem);
-
- /* there better not be anyone else
- * holding the write lock here */
- ASSERT(rwlp->rw_owner == NULL);
- rwlp->rw_owner = current;
- break;
- default:
- SBUG();
- }
-}
-
-static __inline__ void
-rw_exit(krwlock_t *rwlp)
-{
- ASSERT(rwlp);
- ASSERT(rwlp->rw_magic == RW_MAGIC);
-
- /* rw_owner is held by current
- * thread iff it is a writer */
- if (rwlp->rw_owner == current) {
- rwlp->rw_owner = NULL;
- up_write(&rwlp->rw_sem);
- } else {
- up_read(&rwlp->rw_sem);
- }
-}
-
-static __inline__ void
-rw_downgrade(krwlock_t *rwlp)
-{
- ASSERT(rwlp);
- ASSERT(rwlp->rw_magic == RW_MAGIC);
- ASSERT(rwlp->rw_owner == current);
-
- rwlp->rw_owner = NULL;
- downgrade_write(&rwlp->rw_sem);
-}
-
-/* Return 0 if unable to perform the upgrade.
- * Might be wise to fix the caller
- * to acquire the write lock first?
- */
-static __inline__ int
-rw_tryupgrade(krwlock_t *rwlp)
-{
- int result = 0;
-
- ASSERT(rwlp);
- ASSERT(rwlp->rw_magic == RW_MAGIC);
-
- spin_lock(&rwlp->rw_sem.wait_lock);
-
- /* Check if there is anyone waiting for the
- * lock. If there is, then we know we should
- * not try to upgrade the lock */
- if (!list_empty(&rwlp->rw_sem.wait_list)) {
- spin_unlock(&rwlp->rw_sem.wait_lock);
- return 0;
- }
-#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
- /* Note that activity is protected by
- * the wait_lock. Don't try to upgrade
- * if there are multiple readers currently
- * holding the lock */
- if (rwlp->rw_sem.activity > 1) {
-#else
- /* Don't try to upgrade
- * if there are multiple readers currently
- * holding the lock */
- if ((rwlp->rw_sem.count & RWSEM_ACTIVE_MASK) > 1) {
-#endif
- spin_unlock(&rwlp->rw_sem.wait_lock);
- return 0;
- }
-
-#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
- /* Here it should be safe to drop the
- * read lock and reacquire it for writing since
- * we know there are no waiters */
- __up_read_locked(&rwlp->rw_sem);
-
- /* returns 1 if success, 0 if contention */
- result = __down_write_trylock_locked(&rwlp->rw_sem);
-#else
- /* Here it should be safe to drop the
- * read lock and reacquire it for writing since
- * we know there are no waiters */
- up_read(&rwlp->rw_sem);
-
- /* returns 1 if success, 0 if contention */
- result = down_write_trylock(&rwlp->rw_sem);
-#endif
-
- /* Check if upgrade failed. Should not ever happen
- * if we got to this point */
- ASSERT(result);
- ASSERT(rwlp->rw_owner == NULL);
- rwlp->rw_owner = current;
- spin_unlock(&rwlp->rw_sem.wait_lock);
- return 1;
-}
-
-static __inline__ kthread_t *
-rw_owner(krwlock_t *rwlp)
-{
- ASSERT(rwlp);
- ASSERT(rwlp->rw_magic == RW_MAGIC);
-
- return rwlp->rw_owner;
-}
-
-#ifdef __cplusplus
+#define rw_init(rwlp, name, type, arg) \
+({ \
+ if ((name) == NULL) \
+ __rw_init(rwlp, #rwlp, type, arg); \
+ else \
+ __rw_init(rwlp, name, type, arg); \
+})
+#define rw_destroy(rwlp) __rw_destroy(rwlp)
+#define rw_tryenter(rwlp, rw) __rw_tryenter(rwlp, rw)
+#define rw_enter(rwlp, rw) __rw_enter(rwlp, rw)
+#define rw_exit(rwlp) __rw_exit(rwlp)
+#define rw_downgrade(rwlp) __rw_downgrade(rwlp)
+#define rw_tryupgrade(rwlp) __rw_tryupgrade(rwlp)
+#define rw_owner(rwlp) __rw_owner(rwlp)
+#define RW_READ_HELD(rwlp) __rw_read_held(rwlp)
+#define RW_WRITE_HELD(rwlp) __rw_write_held(rwlp)
+#define RW_LOCK_HELD(rwlp) __rw_lock_held(rwlp)
+
+#ifdef __cplusplus
}
#endif
-#endif /* _SPL_RWLOCK_H */
+#endif /* _SPL_RWLOCK_H */
#define DEBUG_SUBSYSTEM S_RWLOCK
+#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
+struct rwsem_waiter {
+ struct list_head list;
+ struct task_struct *task;
+ unsigned int flags;
+#define RWSEM_WAITING_FOR_READ 0x00000001
+#define RWSEM_WAITING_FOR_WRITE 0x00000002
+};
+/* wake a single writer */
+static struct rw_semaphore *
+__rwsem_wake_one_writer_locked(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);
+
+ tsk = waiter->task;
+ smp_mb();
+ waiter->task = NULL;
+ wake_up_process(tsk);
+ put_task_struct(tsk);
+ return sem;
+}
+
+/* release a read lock on the semaphore */
+static void
+__up_read_locked(struct rw_semaphore *sem)
+{
+ if (--sem->activity == 0 && !list_empty(&sem->wait_list))
+ sem = __rwsem_wake_one_writer_locked(sem);
+}
+
+/* trylock for writing -- returns 1 if successful, 0 if contention */
+static int
+__down_write_trylock_locked(struct rw_semaphore *sem)
+{
+ int ret = 0;
+
+ if (sem->activity == 0 && list_empty(&sem->wait_list)) {
+ /* granted */
+ sem->activity = -1;
+ ret = 1;
+ }
+
+ return ret;
+}
+#endif
+
+void
+__rw_init(krwlock_t *rwlp, char *name, krw_type_t type, void *arg)
+{
+ int flags = KM_SLEEP;
+
+ ASSERT(rwlp);
+ ASSERT(name);
+ ASSERT(type == RW_DEFAULT); /* XXX no irq handler use */
+ ASSERT(arg == NULL); /* XXX no irq handler use */
+
+ rwlp->rw_magic = RW_MAGIC;
+ rwlp->rw_owner = NULL;
+ rwlp->rw_name = NULL;
+ rwlp->rw_name_size = strlen(name) + 1;
+
+ /* We may be called when there is a non-zero preempt_count or
+ * interrupts are disabled is which case we must not sleep.
+ */
+ if (current_thread_info()->preempt_count || irqs_disabled())
+ flags = KM_NOSLEEP;
+
+ rwlp->rw_name = kmem_alloc(rwlp->rw_name_size, flags);
+ if (rwlp->rw_name == NULL)
+ return;
+
+ init_rwsem(&rwlp->rw_sem);
+ strcpy(rwlp->rw_name, name);
+}
+EXPORT_SYMBOL(__rw_init);
+
+void
+__rw_destroy(krwlock_t *rwlp)
+{
+ ASSERT(rwlp);
+ ASSERT(rwlp->rw_magic == RW_MAGIC);
+ ASSERT(rwlp->rw_owner == NULL);
+ spin_lock(&rwlp->rw_sem.wait_lock);
+ ASSERT(list_empty(&rwlp->rw_sem.wait_list));
+ spin_unlock(&rwlp->rw_sem.wait_lock);
+
+ kmem_free(rwlp->rw_name, rwlp->rw_name_size);
+
+ memset(rwlp, RW_POISON, sizeof(krwlock_t));
+}
+EXPORT_SYMBOL(__rw_destroy);
+
+/* Return 0 if the lock could not be obtained without blocking. */
+int
+__rw_tryenter(krwlock_t *rwlp, krw_t rw)
+{
+ int rc = 0;
+ ENTRY;
+
+ ASSERT(rwlp);
+ ASSERT(rwlp->rw_magic == RW_MAGIC);
+
+ switch (rw) {
+ /* these functions return 1 if success, 0 if contention */
+ case RW_READER:
+ /* Here the Solaris code would return 0
+ * if there were any write waiters. Specifically
+ * thinking about the case where readers may have
+ * the lock and we would also allow this thread
+ * to grab the read lock with a writer waiting in the
+ * queue. This doesn't seem like a correctness
+ * issue, so just call down_read_trylock()
+ * for the test. We may have to revisit this if
+ * it becomes an issue */
+ rc = down_read_trylock(&rwlp->rw_sem);
+ break;
+ case RW_WRITER:
+ rc = down_write_trylock(&rwlp->rw_sem);
+ if (rc) {
+ /* there better not be anyone else
+ * holding the write lock here */
+ ASSERT(rwlp->rw_owner == NULL);
+ rwlp->rw_owner = current;
+ }
+ break;
+ default:
+ SBUG();
+ }
+
+ RETURN(rc);
+}
+EXPORT_SYMBOL(__rw_tryenter);
+
+void
+__rw_enter(krwlock_t *rwlp, krw_t rw)
+{
+ ENTRY;
+ ASSERT(rwlp);
+ ASSERT(rwlp->rw_magic == RW_MAGIC);
+
+ switch (rw) {
+ case RW_READER:
+ /* Here the Solaris code would block
+ * if there were any write waiters. Specifically
+ * thinking about the case where readers may have
+ * the lock and we would also allow this thread
+ * to grab the read lock with a writer waiting in the
+ * queue. This doesn't seem like a correctness
+ * issue, so just call down_read()
+ * for the test. We may have to revisit this if
+ * it becomes an issue */
+ down_read(&rwlp->rw_sem);
+ break;
+ case RW_WRITER:
+ down_write(&rwlp->rw_sem);
+
+ /* there better not be anyone else
+ * holding the write lock here */
+ ASSERT(rwlp->rw_owner == NULL);
+ rwlp->rw_owner = current;
+ break;
+ default:
+ SBUG();
+ }
+ EXIT;
+}
+EXPORT_SYMBOL(__rw_enter);
+
+void
+__rw_exit(krwlock_t *rwlp)
+{
+ ENTRY;
+ ASSERT(rwlp);
+ ASSERT(rwlp->rw_magic == RW_MAGIC);
+
+ /* rw_owner is held by current
+ * thread iff it is a writer */
+ if (rwlp->rw_owner == current) {
+ rwlp->rw_owner = NULL;
+ up_write(&rwlp->rw_sem);
+ } else {
+ up_read(&rwlp->rw_sem);
+ }
+ EXIT;
+}
+EXPORT_SYMBOL(__rw_exit);
+
+void
+__rw_downgrade(krwlock_t *rwlp)
+{
+ ENTRY;
+ ASSERT(rwlp);
+ ASSERT(rwlp->rw_magic == RW_MAGIC);
+ ASSERT(rwlp->rw_owner == current);
+
+ rwlp->rw_owner = NULL;
+ downgrade_write(&rwlp->rw_sem);
+ EXIT;
+}
+EXPORT_SYMBOL(__rw_downgrade);
+
+/* Return 0 if unable to perform the upgrade.
+ * Might be wise to fix the caller
+ * to acquire the write lock first?
+ */
+int
+__rw_tryupgrade(krwlock_t *rwlp)
+{
+ int rc = 0;
+ ENTRY;
+
+ ASSERT(rwlp);
+ ASSERT(rwlp->rw_magic == RW_MAGIC);
+
+ spin_lock(&rwlp->rw_sem.wait_lock);
+
+ /* Check if there is anyone waiting for the
+ * lock. If there is, then we know we should
+ * not try to upgrade the lock */
+ if (!list_empty(&rwlp->rw_sem.wait_list)) {
+ spin_unlock(&rwlp->rw_sem.wait_lock);
+ RETURN(0);
+ }
+#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
+ /* Note that activity is protected by
+ * the wait_lock. Don't try to upgrade
+ * if there are multiple readers currently
+ * holding the lock */
+ if (rwlp->rw_sem.activity > 1) {
+#else
+ /* Don't try to upgrade
+ * if there are multiple readers currently
+ * holding the lock */
+ if ((rwlp->rw_sem.count & RWSEM_ACTIVE_MASK) > 1) {
+#endif
+ spin_unlock(&rwlp->rw_sem.wait_lock);
+ RETURN(0);
+ }
+
+#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
+ /* Here it should be safe to drop the
+ * read lock and reacquire it for writing since
+ * we know there are no waiters */
+ __up_read_locked(&rwlp->rw_sem);
+
+ /* returns 1 if success, 0 if contention */
+ rc = __down_write_trylock_locked(&rwlp->rw_sem);
+#else
+ /* Here it should be safe to drop the
+ * read lock and reacquire it for writing since
+ * we know there are no waiters */
+ up_read(&rwlp->rw_sem);
+
+ /* returns 1 if success, 0 if contention */
+ rc = down_write_trylock(&rwlp->rw_sem);
+#endif
+
+ /* Check if upgrade failed. Should not ever happen
+ * if we got to this point */
+ ASSERT(rc);
+ ASSERT(rwlp->rw_owner == NULL);
+ rwlp->rw_owner = current;
+ spin_unlock(&rwlp->rw_sem.wait_lock);
+
+ RETURN(1);
+}
+EXPORT_SYMBOL(__rw_tryupgrade);
+
+kthread_t *
+__rw_owner(krwlock_t *rwlp)
+{
+ ENTRY;
+ ASSERT(rwlp);
+ ASSERT(rwlp->rw_magic == RW_MAGIC);
+ RETURN(rwlp->rw_owner);
+}
+EXPORT_SYMBOL(__rw_owner);
+
int
__rw_read_held(krwlock_t *rwlp)
{
ENTRY;
+ ASSERT(rwlp);
ASSERT(rwlp->rw_magic == RW_MAGIC);
RETURN(__rw_lock_held(rwlp) && rwlp->rw_owner == NULL);
}
__rw_write_held(krwlock_t *rwlp)
{
ENTRY;
+ ASSERT(rwlp);
ASSERT(rwlp->rw_magic == RW_MAGIC);
RETURN(rwlp->rw_owner == current);
}
int rc = 0;
ENTRY;
+ ASSERT(rwlp);
ASSERT(rwlp->rw_magic == RW_MAGIC);
spin_lock_irq(&(rwlp->rw_sem.wait_lock));
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