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fix the following softint parallel operation problem.

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(0) softint handler "handler A" is established
(1) CPU#X does softint_schedule() for "handler A"
    - the softhand_t is set SOFTINT_PENDING flag
    - the softhand_t is NOT set SOFTINT_ACTIVE flag yet
(2) CPU#X begins other H/W interrupt processing
(3) CPU#Y does softint_disestablish() for "handler A"
    - waits until softhand_t's SOFTINT_ACTIVE of all CPUs is clear
    - the softhand_t is set not SOFTINT_ACTIVE but SOFTINT_PENDING,
      so CPU#Y does not wait
    - unset the function of "handler A"
(4) CPU#X does softint_execute()
    - the function of "handler A" is already clear, so panic
This commit is contained in:
knakahara 2015-12-24 02:27:14 +00:00
parent 11804462b9
commit 26cfaca81e
1 changed files with 4 additions and 4 deletions
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8
sys/kern/kern_softint.c
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@ -1,4 +1,4 @@
/* $NetBSD: kern_softint.c,v 1.41 2014/05/25 15:42:01 rmind Exp $ */
/* $NetBSD: kern_softint.c,v 1.42 2015/12/24 02:27:14 knakahara Exp $ */
/*-
* Copyright (c) 2007, 2008 The NetBSD Foundation, Inc.
@ -170,7 +170,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_softint.c,v 1.41 2014/05/25 15:42:01 rmind Exp $");
__KERNEL_RCSID(0, "$NetBSD: kern_softint.c,v 1.42 2015/12/24 02:27:14 knakahara Exp $");
#include <sys/param.h>
#include <sys/proc.h>
@ -442,8 +442,8 @@ softint_disestablish(void *arg)
KASSERT(sh->sh_func != NULL);
flags |= sh->sh_flags;
}
/* Inactive on all CPUs? */
if ((flags & SOFTINT_ACTIVE) == 0) {
/* Neither pending nor active on all CPUs? */
if ((flags & (SOFTINT_PENDING | SOFTINT_ACTIVE)) == 0) {
break;
}
/* Oops, still active. Wait for it to clear. */