- Change FPCPU_LOCK() such that the caller is responsible for blocking
IPIs in the MULTIPROCESSOR case. Adjust all callers. - In fpusave_cpu(), block IPIs for the entire duration (while we have CPUF_FPUSAVE set in ci_flags) to fix the deadlock that leads to "panic: fpsave ipi didn't", as described in PR port-alpha/26383. Many thanks to Michael Hitch for the analysis and initial patch which this one is derived from.
This commit is contained in:
thorpej
parent
85de2d6607
commit
8919f50566
@ -1,4 +1,4 @@
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/* $NetBSD: machdep.c,v 1.286 2005/06/03 15:06:40 jdc Exp $ */
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/* $NetBSD: machdep.c,v 1.287 2005/07/28 13:57:06 thorpej Exp $ */
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/*-
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* Copyright (c) 1998, 1999, 2000 The NetBSD Foundation, Inc.
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@ -75,7 +75,7 @@
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#include <sys/cdefs.h> /* RCS ID & Copyright macro defns */
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__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.286 2005/06/03 15:06:40 jdc Exp $");
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__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.287 2005/07/28 13:57:06 thorpej Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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@ -1706,6 +1706,7 @@ fpusave_cpu(struct cpu_info *ci, int save)
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KDASSERT(ci == curcpu());
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#if defined(MULTIPROCESSOR)
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s = splhigh(); /* block IPIs for the duration */
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atomic_setbits_ulong(&ci->ci_flags, CPUF_FPUSAVE);
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#endif
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@ -1720,16 +1721,17 @@ fpusave_cpu(struct cpu_info *ci, int save)
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alpha_pal_wrfen(0);
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FPCPU_LOCK(&l->l_addr->u_pcb, s);
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FPCPU_LOCK(&l->l_addr->u_pcb);
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l->l_addr->u_pcb.pcb_fpcpu = NULL;
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ci->ci_fpcurlwp = NULL;
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FPCPU_UNLOCK(&l->l_addr->u_pcb, s);
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FPCPU_UNLOCK(&l->l_addr->u_pcb);
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out:
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#if defined(MULTIPROCESSOR)
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atomic_clearbits_ulong(&ci->ci_flags, CPUF_FPUSAVE);
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splx(s);
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#endif
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return;
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}
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@ -1749,25 +1751,32 @@ fpusave_proc(struct lwp *l, int save)
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KDASSERT(l->l_addr != NULL);
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FPCPU_LOCK(&l->l_addr->u_pcb, s);
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#if defined(MULTIPROCESSOR)
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s = splhigh(); /* block IPIs for the duration */
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#endif
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FPCPU_LOCK(&l->l_addr->u_pcb);
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oci = l->l_addr->u_pcb.pcb_fpcpu;
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if (oci == NULL) {
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FPCPU_UNLOCK(&l->l_addr->u_pcb, s);
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FPCPU_UNLOCK(&l->l_addr->u_pcb);
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#if defined(MULTIPROCESSOR)
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splx(s);
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#endif
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return;
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}
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#if defined(MULTIPROCESSOR)
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if (oci == ci) {
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KASSERT(ci->ci_fpcurlwp == l);
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FPCPU_UNLOCK(&l->l_addr->u_pcb, s);
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FPCPU_UNLOCK(&l->l_addr->u_pcb);
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splx(s);
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fpusave_cpu(ci, save);
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return;
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}
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KASSERT(oci->ci_fpcurlwp == l);
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alpha_send_ipi(oci->ci_cpuid, ipi);
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FPCPU_UNLOCK(&l->l_addr->u_pcb, s);
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FPCPU_UNLOCK(&l->l_addr->u_pcb);
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spincount = 0;
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while (l->l_addr->u_pcb.pcb_fpcpu != NULL) {
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@ -1778,7 +1787,7 @@ fpusave_proc(struct lwp *l, int save)
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}
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#else
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KASSERT(ci->ci_fpcurlwp == l);
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FPCPU_UNLOCK(&l->l_addr->u_pcb, s);
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FPCPU_UNLOCK(&l->l_addr->u_pcb);
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fpusave_cpu(ci, save);
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#endif /* MULTIPROCESSOR */
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}
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@ -1,4 +1,4 @@
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/* $NetBSD: trap.c,v 1.97 2005/06/01 16:09:01 drochner Exp $ */
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/* $NetBSD: trap.c,v 1.98 2005/07/28 13:57:06 thorpej Exp $ */
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/*-
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* Copyright (c) 2000, 2001 The NetBSD Foundation, Inc.
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@ -100,7 +100,7 @@
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#include <sys/cdefs.h> /* RCS ID & Copyright macro defns */
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__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.97 2005/06/01 16:09:01 drochner Exp $");
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__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.98 2005/07/28 13:57:06 thorpej Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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@ -634,12 +634,18 @@ alpha_enable_fp(struct lwp *l, int check)
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KDASSERT(l->l_addr->u_pcb.pcb_fpcpu == NULL);
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#endif
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FPCPU_LOCK(&l->l_addr->u_pcb, s);
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#if defined(MULTIPROCESSOR)
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s = splhigh(); /* block IPIs */
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#endif
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FPCPU_LOCK(&l->l_addr->u_pcb);
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l->l_addr->u_pcb.pcb_fpcpu = ci;
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ci->ci_fpcurlwp = l;
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FPCPU_UNLOCK(&l->l_addr->u_pcb, s);
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FPCPU_UNLOCK(&l->l_addr->u_pcb);
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#if defined(MULTIPROCESSOR)
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splx(s);
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#endif
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/*
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* Instrument FP usage -- if a process had not previously
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@ -1,4 +1,4 @@
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/* $NetBSD: pcb.h,v 1.12 2003/06/29 22:28:05 fvdl Exp $ */
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/* $NetBSD: pcb.h,v 1.13 2005/07/28 13:57:06 thorpej Exp $ */
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/*
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* Copyright (c) 1994, 1995, 1996 Carnegie-Mellon University.
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@ -64,25 +64,13 @@ struct pcb {
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struct simplelock pcb_fpcpu_slock; /* simple lock on fpcpu [SW] */
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};
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#if defined(MULTIPROCESSOR)
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/*
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* Need to block IPIs while holding the fpcpu_slock.
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* MULTIPROCESSOR:
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* Need to block IPIs while holding the fpcpu_slock. That is the
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* responsibility of the CALLER!
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*/
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#define FPCPU_LOCK(pcb, s) \
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do { \
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(s) = splhigh(); \
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simple_lock(&(pcb)->pcb_fpcpu_slock); \
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} while (/*CONSTCOND*/0)
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#define FPCPU_UNLOCK(pcb, s) \
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do { \
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simple_unlock(&(pcb)->pcb_fpcpu_slock); \
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splx((s)); \
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} while (/*CONSTCOND*/0)
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#else
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#define FPCPU_LOCK(pcb, s) simple_lock(&(pcb)->pcb_fpcpu_slock)
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#define FPCPU_UNLOCK(pcb, s) simple_unlock(&(pcb)->pcb_fpcpu_slock)
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#endif /* MULTIPROCESSOR */
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#define FPCPU_LOCK(pcb) simple_lock(&(pcb)->pcb_fpcpu_slock)
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#define FPCPU_UNLOCK(pcb) simple_unlock(&(pcb)->pcb_fpcpu_slock)
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/*
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* The pcb is augmented with machine-dependent additional data for
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