staging: lustre: replace cfs_rand() with prandom_u32_max()

All occurrences of
   cfs_rand() % X
are replaced with
   prandom_u32_max(X)

cfs_rand() is a simple Linear Congruential PRNG.  prandom_u32_max()
is at least as random, is seeded with more randomness, and uses
cpu-local state to avoid cross-cpu issues.

This is the first step is discarding the libcfs prng with
the standard linux prng.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lnet/libcfs/fail.c b/drivers/staging/lustre/lnet/libcfs/fail.c
index 5d501beeb62235a101dd72e35a49986e38e071ca..39439b303d654a520cb126200e2b55fd5d127be1 100644 (file)
--- a/drivers/staging/lustre/lnet/libcfs/fail.c
+++ b/drivers/staging/lustre/lnet/libcfs/fail.c
@@ -61,7 +61,7 @@ int __cfs_fail_check_set(u32 id, u32 value, int set)
 
        /* Fail 1/cfs_fail_val times */
        if (cfs_fail_loc & CFS_FAIL_RAND) {
-               if (cfs_fail_val < 2 || cfs_rand() % cfs_fail_val > 0)
+               if (cfs_fail_val < 2 || prandom_u32_max(cfs_fail_val) > 0)
                        return 0;
        }
 

diff --git a/drivers/staging/lustre/lnet/lnet/net_fault.c b/drivers/staging/lustre/lnet/lnet/net_fault.c
index 5a5d1811ffbeac436dd02fd8fc5700569ae5ef25..0ee7e20ba151c9fc6b458da81f16ff4b4a9a293b 100644 (file)
--- a/drivers/staging/lustre/lnet/lnet/net_fault.c
+++ b/drivers/staging/lustre/lnet/lnet/net_fault.c
@@ -170,10 +170,10 @@ lnet_drop_rule_add(struct lnet_fault_attr *attr)
        rule->dr_attr = *attr;
        if (attr->u.drop.da_interval) {
                rule->dr_time_base = cfs_time_shift(attr->u.drop.da_interval);
-               rule->dr_drop_time = cfs_time_shift(cfs_rand() %
-                                                   attr->u.drop.da_interval);
+               rule->dr_drop_time = cfs_time_shift(
+                       prandom_u32_max(attr->u.drop.da_interval));
        } else {
-               rule->dr_drop_at = cfs_rand() % attr->u.drop.da_rate;
+               rule->dr_drop_at = prandom_u32_max(attr->u.drop.da_rate);
        }
 
        lnet_net_lock(LNET_LOCK_EX);
@@ -277,10 +277,10 @@ lnet_drop_rule_reset(void)
 
                memset(&rule->dr_stat, 0, sizeof(rule->dr_stat));
                if (attr->u.drop.da_rate) {
-                       rule->dr_drop_at = cfs_rand() % attr->u.drop.da_rate;
+                       rule->dr_drop_at = prandom_u32_max(attr->u.drop.da_rate);
                } else {
-                       rule->dr_drop_time = cfs_time_shift(cfs_rand() %
-                                               attr->u.drop.da_interval);
+                       rule->dr_drop_time = cfs_time_shift(
+                               prandom_u32_max(attr->u.drop.da_interval));
                        rule->dr_time_base = cfs_time_shift(attr->u.drop.da_interval);
                }
                spin_unlock(&rule->dr_lock);
@@ -315,8 +315,8 @@ drop_rule_match(struct lnet_drop_rule *rule, lnet_nid_t src,
                                rule->dr_time_base = now;
 
                        rule->dr_drop_time = rule->dr_time_base +
-                                            cfs_time_seconds(cfs_rand() %
-                                               attr->u.drop.da_interval);
+                               cfs_time_seconds(
+                                       prandom_u32_max(attr->u.drop.da_interval));
                        rule->dr_time_base += cfs_time_seconds(attr->u.drop.da_interval);
 
                        CDEBUG(D_NET, "Drop Rule %s->%s: next drop : %lu\n",
@@ -330,7 +330,7 @@ drop_rule_match(struct lnet_drop_rule *rule, lnet_nid_t src,
 
                if (!do_div(rule->dr_stat.fs_count, attr->u.drop.da_rate)) {
                        rule->dr_drop_at = rule->dr_stat.fs_count +
-                                          cfs_rand() % attr->u.drop.da_rate;
+                               prandom_u32_max(attr->u.drop.da_rate);
                        CDEBUG(D_NET, "Drop Rule %s->%s: next drop: %lu\n",
                               libcfs_nid2str(attr->fa_src),
                               libcfs_nid2str(attr->fa_dst), rule->dr_drop_at);
@@ -483,8 +483,9 @@ delay_rule_match(struct lnet_delay_rule *rule, lnet_nid_t src,
                                rule->dl_time_base = now;
 
                        rule->dl_delay_time = rule->dl_time_base +
-                                            cfs_time_seconds(cfs_rand() %
-                                               attr->u.delay.la_interval);
+                               cfs_time_seconds(
+                                       prandom_u32_max(
+                                               attr->u.delay.la_interval));
                        rule->dl_time_base += cfs_time_seconds(attr->u.delay.la_interval);
 
                        CDEBUG(D_NET, "Delay Rule %s->%s: next delay : %lu\n",
@@ -498,7 +499,7 @@ delay_rule_match(struct lnet_delay_rule *rule, lnet_nid_t src,
                /* generate the next random rate sequence */
                if (!do_div(rule->dl_stat.fs_count, attr->u.delay.la_rate)) {
                        rule->dl_delay_at = rule->dl_stat.fs_count +
-                                           cfs_rand() % attr->u.delay.la_rate;
+                               prandom_u32_max(attr->u.delay.la_rate);
                        CDEBUG(D_NET, "Delay Rule %s->%s: next delay: %lu\n",
                               libcfs_nid2str(attr->fa_src),
                               libcfs_nid2str(attr->fa_dst), rule->dl_delay_at);
@@ -771,10 +772,10 @@ lnet_delay_rule_add(struct lnet_fault_attr *attr)
        rule->dl_attr = *attr;
        if (attr->u.delay.la_interval) {
                rule->dl_time_base = cfs_time_shift(attr->u.delay.la_interval);
-               rule->dl_delay_time = cfs_time_shift(cfs_rand() %
-                                                    attr->u.delay.la_interval);
+               rule->dl_delay_time = cfs_time_shift(
+                       prandom_u32_max(attr->u.delay.la_interval));
        } else {
-               rule->dl_delay_at = cfs_rand() % attr->u.delay.la_rate;
+               rule->dl_delay_at = prandom_u32_max(attr->u.delay.la_rate);
        }
 
        rule->dl_msg_send = -1;
@@ -920,10 +921,11 @@ lnet_delay_rule_reset(void)
 
                memset(&rule->dl_stat, 0, sizeof(rule->dl_stat));
                if (attr->u.delay.la_rate) {
-                       rule->dl_delay_at = cfs_rand() % attr->u.delay.la_rate;
+                       rule->dl_delay_at = prandom_u32_max(attr->u.delay.la_rate);
                } else {
-                       rule->dl_delay_time = cfs_time_shift(cfs_rand() %
-                                               attr->u.delay.la_interval);
+                       rule->dl_delay_time =
+                               cfs_time_shift(prandom_u32_max(
+                                                      attr->u.delay.la_interval));
                        rule->dl_time_base = cfs_time_shift(attr->u.delay.la_interval);
                }
                spin_unlock(&rule->dl_lock);

diff --git a/drivers/staging/lustre/lnet/lnet/router.c b/drivers/staging/lustre/lnet/lnet/router.c
index 88283ca3f860ac880ea58efc8ece9ff1e36be9d2..6885d7cd094f5aa282522005b4c36324891b9343 100644 (file)
--- a/drivers/staging/lustre/lnet/lnet/router.c
+++ b/drivers/staging/lustre/lnet/lnet/router.c
@@ -277,8 +277,8 @@ lnet_add_route_to_rnet(struct lnet_remotenet *rnet, struct lnet_route *route)
                len++;
        }
 
-       /* len+1 positions to add a new entry, also prevents division by 0 */
-       offset = cfs_rand() % (len + 1);
+       /* len+1 positions to add a new entry */
+       offset = prandom_u32_max(len + 1);
        list_for_each(e, &rnet->lrn_routes) {
                if (!offset)
                        break;

diff --git a/drivers/staging/lustre/lustre/mgc/mgc_request.c b/drivers/staging/lustre/lustre/mgc/mgc_request.c
index 77fa8fea0249d10b5e3cd300621a03f2f09deeea..79ff85feab6429215e735368e7793f3073ee2d87 100644 (file)
--- a/drivers/staging/lustre/lustre/mgc/mgc_request.c
+++ b/drivers/staging/lustre/lustre/mgc/mgc_request.c
@@ -523,7 +523,7 @@ static void do_requeue(struct config_llog_data *cld)
  * in order to not flood the MGS.
  */
 #define MGC_TIMEOUT_MIN_SECONDS   5
-#define MGC_TIMEOUT_RAND_CENTISEC 0x1ff /* ~500 */
+#define MGC_TIMEOUT_RAND_CENTISEC 500
 
 static int mgc_requeue_thread(void *data)
 {
@@ -537,7 +537,7 @@ static int mgc_requeue_thread(void *data)
        while (!(rq_state & RQ_STOP)) {
                struct l_wait_info lwi;
                struct config_llog_data *cld, *cld_prev;
-               int rand = cfs_rand() & MGC_TIMEOUT_RAND_CENTISEC;
+               int rand = prandom_u32_max(MGC_TIMEOUT_RAND_CENTISEC);
                int to;
 
                /* Any new or requeued lostlocks will change the state */