7 files changed, 32 insertions, 76 deletions

diff --git a/share/man/man9/random.9 b/share/man/man9/random.9
index 97218dcab39c..fb5f2156df16 100644
--- a/share/man/man9/random.9
+++ b/share/man/man9/random.9
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\" "
-.Dd April 16, 2019
+.Dd December 26, 2019
 .Dt RANDOM 9
 .Os
 .Sh NAME
@@ -36,8 +36,7 @@
 .Nm is_random_seeded ,
 .Nm random ,
 .Nm read_random ,
-.Nm read_random_uio ,
-.Nm srandom
+.Nm read_random_uio
 .Nd supply pseudo-random numbers
 .Sh SYNOPSIS
 .In sys/libkern.h
@@ -57,8 +56,6 @@
 .Fn read_random_uio "struct uio *uio" "bool nonblock"
 .Ss LEGACY ROUTINES
 .In sys/libkern.h
-.Ft void
-.Fn srandom "u_long seed"
 .Ft u_long
 .Fn random "void"
 .Sh DESCRIPTION
@@ -134,19 +131,16 @@ Otherwise, this function may block interruptibly until the random device is seed
 If the function is interrupted before the random device is seeded, no data is
 returned.
 .Pp
-The legacy
-.Fn random
-function will produce a sequence of numbers that can be duplicated by calling
-.Fn srandom
-with some constant as the
-.Fa seed .
-The legacy
-.Fn srandom
-function may be called with any
-.Fa seed
-value.
+The deprecated
+.Xr random 9
+function will produce a sequence of pseudorandom numbers using a similar weak
+linear congruential generator as
+.Xr rand 3
+(the 1988 Park-Miller LCG).
+It is obsolete and scheduled to be removed in
+.Fx 13.0 .
 It is strongly advised that the
-.Fn random
+.Xr random 9
 function not be used to generate random numbers.
 See
 .Sx SECURITY CONSIDERATIONS .
@@ -173,23 +167,6 @@ the number of bytes placed in
 .Fn read_random_uio
 returns zero when successful,
 otherwise an error code is returned.
-.Pp
-The legacy
-.Fn random
-function uses
-a non-linear additive feedback random number generator
-employing a default table
-of size 31
-containing long integers
-to return successive pseudo-random
-numbers in the range from 0 to
-.if t 2\u\s731\s10\d\(mi1.
-.if n (2**31)\(mi1.
-The period of this random number generator
-is very large,
-approximately
-.if t 16\(mu(2\u\s731\s10\d\(mi1).
-.if n 16*((2**31)\(mi1).
 .Sh ERRORS
 .Fn read_random_uio
 may fail if:
@@ -212,8 +189,6 @@ wrote
 .Sh SECURITY CONSIDERATIONS
 Do not use
 .Fn random
-or
-.Fn srandom
 in new code.
 .Pp
 It is important to remember that the
diff --git a/sys/compat/ndis/subr_ntoskrnl.c b/sys/compat/ndis/subr_ntoskrnl.c
index 574889f202c6..f8600c3825e7 100644
--- a/sys/compat/ndis/subr_ntoskrnl.c
+++ b/sys/compat/ndis/subr_ntoskrnl.c
@@ -3195,10 +3195,8 @@ rand(void)
 }
 
 static void
-srand(unsigned int seed)
+srand(unsigned int seed __unused)
 {
-
-	srandom(seed);
 }
 
 static uint8_t
diff --git a/sys/dev/oce/oce_mbox.c b/sys/dev/oce/oce_mbox.c
index a1926526edbf..05dac5847cb8 100644
--- a/sys/dev/oce/oce_mbox.c
+++ b/sys/dev/oce/oce_mbox.c
@@ -859,7 +859,6 @@ oce_config_nic_rss(POCE_SOFTC sc, uint32_t if_id, uint16_t enable_rss)
 
 	fwcmd->params.req.if_id = LE_32(if_id);
 
-	srandom(arc4random());	/* random entropy seed */
 	read_random(fwcmd->params.req.hash, sizeof(fwcmd->params.req.hash));
 	
 	rc = oce_rss_itbl_init(sc, fwcmd);
diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 6d4e7b432818..b2df117d1115 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -624,7 +624,6 @@ SYSINIT(p0init, SI_SUB_INTRINSIC, SI_ORDER_FIRST, proc0_init, NULL);
 static void
 proc0_post(void *dummy __unused)
 {
-	struct timespec ts;
 	struct proc *p;
 	struct rusage ru;
 	struct thread *td;
@@ -656,28 +655,9 @@ proc0_post(void *dummy __unused)
 	sx_sunlock(&allproc_lock);
 	PCPU_SET(switchtime, cpu_ticks());
 	PCPU_SET(switchticks, ticks);
-
-	/*
-	 * Give the ``random'' number generator a thump.
-	 */
-	nanotime(&ts);
-	srandom(ts.tv_sec ^ ts.tv_nsec);
 }
 SYSINIT(p0post, SI_SUB_INTRINSIC_POST, SI_ORDER_FIRST, proc0_post, NULL);
 
-static void
-random_init(void *dummy __unused)
-{
-
-	/*
-	 * After CPU has been started we have some randomness on most
-	 * platforms via get_cyclecount().  For platforms that don't
-	 * we will reseed random(9) in proc0_post() as well.
-	 */
-	srandom(get_cyclecount());
-}
-SYSINIT(random, SI_SUB_RANDOM, SI_ORDER_FIRST, random_init, NULL);
-
 /*
  ***************************************************************************
  ****
diff --git a/sys/kern/subr_stats.c b/sys/kern/subr_stats.c
index bbdc1039237e..a212f739deca 100644
--- a/sys/kern/subr_stats.c
+++ b/sys/kern/subr_stats.c
@@ -2963,7 +2963,14 @@ stats_v1_vsd_tdgst_compress(enum vsd_dtype vs_dtype,
 	 * re-inserting the mu/cnt of each as a value and corresponding weight.
 	 */
 
-#define	bitsperrand 31 /* Per random(3). */
+	/*
+	 * XXXCEM: random(9) is currently rand(3), not random(3).  rand(3)
+	 * RAND_MAX happens to be approximately 31 bits (range [0,
+	 * 0x7ffffffd]), so the math kinda works out.  When/if this portion of
+	 * the code is compiled in userspace, it gets the random(3) behavior,
+	 * which has expected range [0, 0x7fffffff].
+	 */
+#define	bitsperrand 31
 	ebits = 0;
 	nebits = 0;
 	bitsperidx = fls(maxctds);
@@ -2971,7 +2978,6 @@ stats_v1_vsd_tdgst_compress(enum vsd_dtype vs_dtype,
 	    ("%s: bitsperidx=%d, ebits=%d",
 	    __func__, bitsperidx, (int)(sizeof(ebits) << 3)));
 	idxmask = (UINT64_C(1) << bitsperidx) - 1;
-	srandom(stats_sbinuptime());
 
 	/* Initialise the free list with randomised centroid indices. */
 	for (; remctds > 0; remctds--) {
diff --git a/sys/libkern/random.c b/sys/libkern/random.c
index 5f2651130ab7..e5e9de6108e1 100644
--- a/sys/libkern/random.c
+++ b/sys/libkern/random.c
@@ -34,32 +34,31 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include <sys/types.h>
 #include <sys/libkern.h>
-
-#define NSHUFF 50       /* to drop some "seed -> 1st value" linearity */
+#include <sys/systm.h>
 
 static u_long randseed = 937186357; /* after srandom(1), NSHUFF counted */
 
-void
-srandom(u_long seed)
-{
-	int i;
-
-	randseed = seed;
-	for (i = 0; i < NSHUFF; i++)
-		(void)random();
-}
-
 /*
  * Pseudo-random number generator for perturbing the profiling clock,
  * and whatever else we might use it for.  The result is uniform on
  * [0, 2^31 - 1].
  */
 u_long
-random()
+random(void)
 {
+	static bool warned = false;
+
 	long x, hi, lo, t;
 
+	/* Warn only once, or it gets very spammy. */
+	if (!warned) {
+		gone_in(13,
+		    "random(9) is the obsolete Park-Miller LCG from 1988");
+		warned = true;
+	}
+
 	/*
 	 * Compute x[n + 1] = (7^5 * x[n]) mod (2^31 - 1).
 	 * From "Random number generators: good ones are hard to find",
diff --git a/sys/sys/libkern.h b/sys/sys/libkern.h
index ba182739cfe7..5e873cda726a 100644
--- a/sys/sys/libkern.h
+++ b/sys/sys/libkern.h
@@ -166,7 +166,6 @@ void	 qsort_r(void *base, size_t nmemb, size_t size, void *thunk,
 	    int (*compar)(void *, const void *, const void *));
 u_long	 random(void);
 int	 scanc(u_int, const u_char *, const u_char *, int);
-void	 srandom(u_long);
 int	 strcasecmp(const char *, const char *);
 char	*strcat(char * __restrict, const char * __restrict);
 char	*strchr(const char *, int);