Re: [PATCH v3 02/13] random: add get_random_{bytes,u32,u64,int,long,once}_wait family

[Jason A. Donenfeld]

On Tue, Jun 6, 2017 at 7:11 AM, Jeffrey Walton  wrote:
> On Mon, Jun 5, 2017 at 8:50 PM, Jason A. Donenfeld  wrote:
>> These functions are simple convenience wrappers that call
>> wait_for_random_bytes before calling the respective get_random_*
>> function.
>
> It may be advantageous to add a timeout, too.

This was in v1, but was removed because of a lack of particular use
case in this context.

Re: [PATCH v3 02/13] random: add get_random_{bytes,u32,u64,int,long,once}_wait family

[Jeffrey Walton]

On Mon, Jun 5, 2017 at 8:50 PM, Jason A. Donenfeld  wrote:
> These functions are simple convenience wrappers that call
> wait_for_random_bytes before calling the respective get_random_*
> function.

It may be advantageous to add a timeout, too.

There's been a number of times I did not want to wait an INFINITE
amount of time for a completion. (In another context).

Jeff

> Signed-off-by: Jason A. Donenfeld 
> ---
>  include/linux/net.h|  2 ++
>  include/linux/once.h   |  2 ++
>  include/linux/random.h | 25 +
>  3 files changed, 29 insertions(+)
>
> diff --git a/include/linux/net.h b/include/linux/net.h
> index abcfa46a2bd9..dda2cc939a53 100644
> --- a/include/linux/net.h
> +++ b/include/linux/net.h
> @@ -274,6 +274,8 @@ do {  
>   \
>
>  #define net_get_random_once(buf, nbytes)   \
> get_random_once((buf), (nbytes))
> +#define net_get_random_once_wait(buf, nbytes)  \
> +   get_random_once_wait((buf), (nbytes))
>
>  int kernel_sendmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,
>size_t num, size_t len);
> diff --git a/include/linux/once.h b/include/linux/once.h
> index 285f12cb40e6..9c98aaa87cbc 100644
> --- a/include/linux/once.h
> +++ b/include/linux/once.h
> @@ -53,5 +53,7 @@ void __do_once_done(bool *done, struct static_key *once_key,
>
>  #define get_random_once(buf, nbytes)\
> DO_ONCE(get_random_bytes, (buf), (nbytes))
> +#define get_random_once_wait(buf, nbytes)
> \
> +   DO_ONCE(get_random_bytes_wait, (buf), (nbytes))  \
>
>  #endif /* _LINUX_ONCE_H */
> diff --git a/include/linux/random.h b/include/linux/random.h
> index e29929347c95..4aecc339558d 100644
> --- a/include/linux/random.h
> +++ b/include/linux/random.h
> @@ -58,6 +58,31 @@ static inline unsigned long get_random_long(void)
>  #endif
>  }
>
> +/* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, 
> nbytes).
> + * Returns the result of the call to wait_for_random_bytes. */
> +static inline int get_random_bytes_wait(void *buf, int nbytes)
> +{
> +   int ret = wait_for_random_bytes();
> +   if (unlikely(ret))
> +   return ret;
> +   get_random_bytes(buf, nbytes);
> +   return 0;
> +}
> +
> +#define declare_get_random_var_wait(var) \
> +   static inline int get_random_ ## var ## _wait(var *out) { \
> +   int ret = wait_for_random_bytes(); \
> +   if (unlikely(ret)) \
> +   return ret; \
> +   *out = get_random_ ## var(); \
> +   return 0; \
> +   }
> +declare_get_random_var_wait(u32)
> +declare_get_random_var_wait(u64)
> +declare_get_random_var_wait(int)
> +declare_get_random_var_wait(long)
> +#undef declare_get_random_var
> +
>  unsigned long randomize_page(unsigned long start, unsigned long range);
>
>  u32 prandom_u32(void);

[PATCH v3 02/13] random: add get_random_{bytes,u32,u64,int,long,once}_wait family

[Jason A. Donenfeld]

These functions are simple convenience wrappers that call
wait_for_random_bytes before calling the respective get_random_*
function.

Signed-off-by: Jason A. Donenfeld 
---
 include/linux/net.h|  2 ++
 include/linux/once.h   |  2 ++
 include/linux/random.h | 25 +
 3 files changed, 29 insertions(+)

diff --git a/include/linux/net.h b/include/linux/net.h
index abcfa46a2bd9..dda2cc939a53 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -274,6 +274,8 @@ do {
\
 
 #define net_get_random_once(buf, nbytes)   \
get_random_once((buf), (nbytes))
+#define net_get_random_once_wait(buf, nbytes)  \
+   get_random_once_wait((buf), (nbytes))
 
 int kernel_sendmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,
   size_t num, size_t len);
diff --git a/include/linux/once.h b/include/linux/once.h
index 285f12cb40e6..9c98aaa87cbc 100644
--- a/include/linux/once.h
+++ b/include/linux/once.h
@@ -53,5 +53,7 @@ void __do_once_done(bool *done, struct static_key *once_key,
 
 #define get_random_once(buf, nbytes)\
DO_ONCE(get_random_bytes, (buf), (nbytes))
+#define get_random_once_wait(buf, nbytes)\
+   DO_ONCE(get_random_bytes_wait, (buf), (nbytes))  \
 
 #endif /* _LINUX_ONCE_H */
diff --git a/include/linux/random.h b/include/linux/random.h
index e29929347c95..4aecc339558d 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -58,6 +58,31 @@ static inline unsigned long get_random_long(void)
 #endif
 }
 
+/* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
+ * Returns the result of the call to wait_for_random_bytes. */
+static inline int get_random_bytes_wait(void *buf, int nbytes)
+{
+   int ret = wait_for_random_bytes();
+   if (unlikely(ret))
+   return ret;
+   get_random_bytes(buf, nbytes);
+   return 0;
+}
+
+#define declare_get_random_var_wait(var) \
+   static inline int get_random_ ## var ## _wait(var *out) { \
+   int ret = wait_for_random_bytes(); \
+   if (unlikely(ret)) \
+   return ret; \
+   *out = get_random_ ## var(); \
+   return 0; \
+   }
+declare_get_random_var_wait(u32)
+declare_get_random_var_wait(u64)
+declare_get_random_var_wait(int)
+declare_get_random_var_wait(long)
+#undef declare_get_random_var
+
 unsigned long randomize_page(unsigned long start, unsigned long range);
 
 u32 prandom_u32(void);
-- 
2.13.0