diff options
| -rw-r--r-- | drivers/char/random.c | 78 | ||||
| -rw-r--r-- | include/linux/random.h | 9 |
2 files changed, 87 insertions, 0 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index 159d0700f7d8..a1576ed1d88e 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -409,6 +409,9 @@ static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); static DECLARE_WAIT_QUEUE_HEAD(urandom_init_wait); static struct fasync_struct *fasync; +static DEFINE_SPINLOCK(random_ready_list_lock); +static LIST_HEAD(random_ready_list); + /********************************************************************** * * OS independent entropy store. Here are the functions which handle @@ -589,6 +592,22 @@ static void fast_mix(struct fast_pool *f) f->count++; } +static void process_random_ready_list(void) +{ + unsigned long flags; + struct random_ready_callback *rdy, *tmp; + + spin_lock_irqsave(&random_ready_list_lock, flags); + list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { + struct module *owner = rdy->owner; + + list_del_init(&rdy->list); + rdy->func(rdy); + module_put(owner); + } + spin_unlock_irqrestore(&random_ready_list_lock, flags); +} + /* * Credit (or debit) the entropy store with n bits of entropy. * Use credit_entropy_bits_safe() if the value comes from userspace @@ -660,6 +679,7 @@ retry: r->entropy_total = 0; if (r == &nonblocking_pool) { prandom_reseed_late(); + process_random_ready_list(); wake_up_all(&urandom_init_wait); pr_notice("random: %s pool is initialized\n", r->name); } @@ -1257,6 +1277,64 @@ void get_blocking_random_bytes(void *buf, int nbytes) EXPORT_SYMBOL(get_blocking_random_bytes); /* + * Add a callback function that will be invoked when the nonblocking + * pool is initialised. + * + * returns: 0 if callback is successfully added + * -EALREADY if pool is already initialised (callback not called) + * -ENOENT if module for callback is not alive + */ +int add_random_ready_callback(struct random_ready_callback *rdy) +{ + struct module *owner; + unsigned long flags; + int err = -EALREADY; + + if (likely(nonblocking_pool.initialized)) + return err; + + owner = rdy->owner; + if (!try_module_get(owner)) + return -ENOENT; + + spin_lock_irqsave(&random_ready_list_lock, flags); + if (nonblocking_pool.initialized) + goto out; + + owner = NULL; + + list_add(&rdy->list, &random_ready_list); + err = 0; + +out: + spin_unlock_irqrestore(&random_ready_list_lock, flags); + + module_put(owner); + + return err; +} +EXPORT_SYMBOL(add_random_ready_callback); + +/* + * Delete a previously registered readiness callback function. + */ +void del_random_ready_callback(struct random_ready_callback *rdy) +{ + unsigned long flags; + struct module *owner = NULL; + + spin_lock_irqsave(&random_ready_list_lock, flags); + if (!list_empty(&rdy->list)) { + list_del_init(&rdy->list); + owner = rdy->owner; + } + spin_unlock_irqrestore(&random_ready_list_lock, flags); + + module_put(owner); +} +EXPORT_SYMBOL(del_random_ready_callback); + +/* * This function will use the architecture-specific hardware random * number generator if it is available. The arch-specific hw RNG will * almost certainly be faster than what we can do in software, but it diff --git a/include/linux/random.h b/include/linux/random.h index 796267d56901..30e2aca0b16a 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -6,8 +6,15 @@ #ifndef _LINUX_RANDOM_H #define _LINUX_RANDOM_H +#include <linux/list.h> #include <uapi/linux/random.h> +struct random_ready_callback { + struct list_head list; + void (*func)(struct random_ready_callback *rdy); + struct module *owner; +}; + extern void add_device_randomness(const void *, unsigned int); extern void add_input_randomness(unsigned int type, unsigned int code, unsigned int value); @@ -15,6 +22,8 @@ extern void add_interrupt_randomness(int irq, int irq_flags); extern void get_random_bytes(void *buf, int nbytes); extern void get_blocking_random_bytes(void *buf, int nbytes); +extern int add_random_ready_callback(struct random_ready_callback *rdy); +extern void del_random_ready_callback(struct random_ready_callback *rdy); extern void get_random_bytes_arch(void *buf, int nbytes); void generate_random_uuid(unsigned char uuid_out[16]); extern int random_int_secret_init(void); |