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Subject[PATCH 1/4] 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>
---
drivers/staging/lustre/lnet/libcfs/fail.c | 2 +
drivers/staging/lustre/lnet/lnet/net_fault.c | 38 ++++++++++++-----------
drivers/staging/lustre/lnet/lnet/router.c | 4 +-
drivers/staging/lustre/lustre/mgc/mgc_request.c | 4 +-
4 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/drivers/staging/lustre/lnet/libcfs/fail.c b/drivers/staging/lustre/lnet/libcfs/fail.c
index 5d501beeb622..39439b303d65 100644
--- 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 0318e64c413f..e3468cef273b 100644
--- 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 c40aa79baf5c..e5c9b29e199f 100644
--- 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 77fa8fea0249..79ff85feab64 100644
--- 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 */

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