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entropy(9): Forbid entropy_extract in hard interrupt context. 

With a little additional work, this will let us reduce the global
entropy pool lock so it never blocks interrupts.
This commit is contained in:
riastradh 2022-03-16 23:56:55 +00:00
parent 8ad5456761
commit a820d532b6
1 changed files with 5 additions and 9 deletions
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14
sys/kern/kern_entropy.c
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@ -1,4 +1,4 @@
/* $NetBSD: kern_entropy.c,v 1.34 2022/03/04 21:12:03 andvar Exp $ */
/* $NetBSD: kern_entropy.c,v 1.35 2022/03/16 23:56:55 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 1.34 2022/03/04 21:12:03 andvar Exp $");
__KERNEL_RCSID(0, "$NetBSD: kern_entropy.c,v 1.35 2022/03/16 23:56:55 riastradh Exp $");
#include <sys/param.h>
#include <sys/types.h>
@ -211,9 +211,6 @@ EVCNT_ATTACH_STATIC(entropy_partial_evcnt);
static struct evcnt entropy_consolidate_evcnt =
EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "entropy", "consolidate");
EVCNT_ATTACH_STATIC(entropy_consolidate_evcnt);
static struct evcnt entropy_extract_intr_evcnt =
EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "entropy", "extract intr");
EVCNT_ATTACH_STATIC(entropy_extract_intr_evcnt);
static struct evcnt entropy_extract_fail_evcnt =
EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "entropy", "extract fail");
EVCNT_ATTACH_STATIC(entropy_extract_fail_evcnt);
@ -1278,14 +1275,13 @@ entropy_extract(void *buf, size_t len, int flags)
"can't wait for entropy until warm");
}
/* Refuse to operate in interrupt context. */
KASSERT(!cpu_intr_p());
/* Acquire the global lock to get at the global pool. */
if (E->stage >= ENTROPY_WARM)
mutex_enter(&E->lock);
/* Count up request for entropy in interrupt context. */
if (cpu_intr_p())
entropy_extract_intr_evcnt.ev_count++;
/* Wait until there is enough entropy in the system. */
error = 0;
while (E->needed) {