Module Name: src
Committed By: riastradh
Date: Wed Jan 13 23:53:23 UTC 2021
Modified Files:
src/sys/kern: kern_entropy.c
Log Message:
entropy: Use a separate condvar for rndsource list lock.
Otherwise, two processes both waiting for entropy will dance around
waking each other up (by releasing the rndsource list lock) and going
back to sleep (waiting for entropy).
Witnessed on the armv7 testbed when /etc/security presumably ran
twice over a >day-long test, until the metaphorical plug got pulled:
net/if_ipsec/t_ipsec_natt (509/888): 2 test cases
ipsecif_natt_transport_null: [ 37123.2631856] entropy: pid 1005 (dd)
blocking due to lack of entropy
[256.523317s] Failed: atf-check failed; see the output of the test for details
ipsecif_natt_transport_rijndaelcbc: [274.370791s] Failed: atf-check failed;
see the output of the test for details
[532.486697s]
...
puffs_lstat_symlink: [ 123442.1606517] entropy: pid 9499 (dd) blocking due
to lack of entropy
[ 123442.1835067] entropy: pid 1005 (dd) blocking due to lack of entropy
[ 123442.1944600] entropy: pid 9499 (dd) blocking due to lack of entropy
[ 123442.1944600] entropy: pid 1005 (dd) blocking due to lack of entropy
...
To generate a diff of this commit:
cvs rdiff -u -r1.26 -r1.27 src/sys/kern/kern_entropy.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_entropy.c
diff -u src/sys/kern/kern_entropy.c:1.26 src/sys/kern/kern_entropy.c:1.27
--- src/sys/kern/kern_entropy.c:1.26 Mon Jan 11 02:18:40 2021
+++ src/sys/kern/kern_entropy.c Wed Jan 13 23:53:23 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_entropy.c,v 1.26 2021/01/11 02:18:40 riastradh Exp $ */
+/* $NetBSD: kern_entropy.c,v 1.27 2021/01/13 23:53:23 riastradh Exp $ */
/*-
* Copyright (c) 2019 The NetBSD Foundation, Inc.
@@ -75,7 +75,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_entropy.c,v 1.26 2021/01/11 02:18:40 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_entropy.c,v 1.27 2021/01/13 23:53:23 riastradh Exp $");
#include <sys/param.h>
#include <sys/types.h>
@@ -161,6 +161,7 @@ struct {
kcondvar_t cv; /* notifies state changes */
struct selinfo selq; /* notifies needed -> 0 */
struct lwp *sourcelock; /* lock on list of sources */
+ kcondvar_t sourcelock_cv; /* notifies sourcelock release */
LIST_HEAD(,krndsource) sources; /* list of entropy sources */
enum entropy_stage {
ENTROPY_COLD = 0, /* single-threaded */
@@ -367,6 +368,7 @@ entropy_init(void)
mutex_init(&E->lock, MUTEX_DEFAULT, IPL_VM);
cv_init(&E->cv, "entropy");
selinit(&E->selq);
+ cv_init(&E->sourcelock_cv, "entsrclock");
/* Make sure the seed source is attached. */
attach_seed_rndsource();
@@ -1594,7 +1596,7 @@ rnd_detach_source(struct krndsource *rs)
/* Wait until the source list is not in use, and remove it. */
mutex_enter(&E->lock);
while (E->sourcelock)
- cv_wait(&E->cv, &E->lock);
+ cv_wait(&E->sourcelock_cv, &E->lock);
LIST_REMOVE(rs, list);
mutex_exit(&E->lock);
@@ -1618,7 +1620,7 @@ rnd_lock_sources(void)
KASSERT(mutex_owned(&E->lock));
while (E->sourcelock) {
- error = cv_wait_sig(&E->cv, &E->lock);
+ error = cv_wait_sig(&E->sourcelock_cv, &E->lock);
if (error)
return error;
}
@@ -1663,7 +1665,7 @@ rnd_unlock_sources(void)
curlwp, E->sourcelock);
E->sourcelock = NULL;
if (E->stage >= ENTROPY_WARM)
- cv_broadcast(&E->cv);
+ cv_signal(&E->sourcelock_cv);
}
/*
