| Message ID | 143216583.t5fUODkLsI@tachyon.chronox.de (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Herbert Xu |
| Headers | show |
On Wed, May 20, 2015 at 07:44:39PM +0200, Stephan Mueller wrote: > > + if (unlikely(nonblocking_pool.initialized == 0)) { > + do { > + rc = wait_event_interruptible(urandom_init_wait, > + nonblocking_pool.initialized); > + } while (rc == -ERESTARTSYS); This is just a convoluted way of doing an uninterruptible sleep. Either make it uninterruptible or allow the function to return an error. Cheers,
Am Donnerstag, 21. Mai 2015, 02:45:35 schrieb Herbert Xu: Hi Herbert, > On Wed, May 20, 2015 at 07:44:39PM +0200, Stephan Mueller wrote: > > + if (unlikely(nonblocking_pool.initialized == 0)) { > > + do { > > + rc = wait_event_interruptible(urandom_init_wait, > > + nonblocking_pool.initialized); > > + } while (rc == -ERESTARTSYS); > > This is just a convoluted way of doing an uninterruptible sleep. > Either make it uninterruptible or allow the function to return > an error. Sorry, I overlooked the availability of wait_event. I was looking for it initially, but missed it. I will fix it right away.
Am Mittwoch, 20. Mai 2015, 20:49:45 schrieb Stephan Mueller: Hi Herbert, > > This is just a convoluted way of doing an uninterruptible sleep. > > Either make it uninterruptible or allow the function to return > > an error. > > Sorry, I overlooked the availability of wait_event. I was looking for it > initially, but missed it. I will fix it right away. After checking a bit more, I see that an uninterruptible sleep cannot be canceled with cancel_work_sync. Therefore, replacing it with wait_event does not work. Thus, go get an uninterruptible sleep which yet can be canceled seems to require wait_event_interruptible together with the check for ERESTARTSYS. Nonetheless, I move the loop out to the DRBG code as requested.
diff --git a/drivers/char/random.c b/drivers/char/random.c index 9cd6968..3d1c027 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1245,6 +1245,24 @@ void get_random_bytes(void *buf, int nbytes) EXPORT_SYMBOL(get_random_bytes); /* + * Equivalent function to get_random_bytes with the difference that this + * function blocks the request until the nonblocking_pool is initialized. + */ +void get_blocking_random_bytes(void *buf, int nbytes) +{ + int rc; + + if (unlikely(nonblocking_pool.initialized == 0)) { + do { + rc = wait_event_interruptible(urandom_init_wait, + nonblocking_pool.initialized); + } while (rc == -ERESTARTSYS); + } + extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0); +} +EXPORT_SYMBOL(get_blocking_random_bytes); + +/* * 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 b05856e..796267d 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -14,6 +14,7 @@ extern void add_input_randomness(unsigned int type, unsigned int code, 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 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);
The added API calls provide a synchronous function call get_blocking_random_bytes where the caller is blocked until the nonblocking_pool is initialized. CC: Andreas Steffen <andreas.steffen@strongswan.org> CC: Theodore Ts'o <tytso@mit.edu> CC: Sandy Harris <sandyinchina@gmail.com> Signed-off-by: Stephan Mueller <smueller@chronox.de> --- drivers/char/random.c | 18 ++++++++++++++++++ include/linux/random.h | 1 + 2 files changed, 19 insertions(+)