Date: 11 Aug 2003 13:10:24 +0100 From: Rui Lopes <rui@ruilopes.com> To: freebsd-hackers@freebsd.org Subject: Possible patch for vm/vm_glue.c Message-ID: <1060603824.650.12.camel@localhost>
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Hello,
I've been reading vm_glue.c and I think I've found a bug regarding the
lock of `proc.p_sflag' inside `scheduler' function.
>From proc.h, "int p_sflag; /* (j) PS_* flags. */" and "(j) - locked by
sched_lock mtx"; but the access is done without having the lock.
Take a look at the attached patch and tell me if this is ok.
Patch made against "$FreeBSD: src/sys/vm/vm_glue.c,v 1.172 2003/05/13
20:36:02 jhb Exp $", but this is also present in current 1.182.
Regards,
Rui Lopes
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# we should only access `proc.p_sflag' when `sched_lock' is locked.
# From proc.h:
# int p_sflag; /* (j) PS_* flags. */
# and j means: "(j) - locked by sched_lock mtx"
# -- Rui Lopes <rui@ruilopes.com>
--- vm_glue.c.orig Mon Aug 11 12:41:33 2003
+++ vm_glue.c Mon Aug 11 12:45:58 2003
@@ -596,10 +596,11 @@
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
struct ksegrp *kg;
+ mtx_lock_spin(&sched_lock);
if (p->p_sflag & (PS_INMEM | PS_SWAPPINGOUT | PS_SWAPPINGIN)) {
+ mtx_unlock_spin(&sched_lock);
continue;
}
- mtx_lock_spin(&sched_lock);
FOREACH_THREAD_IN_PROC(p, td) {
/*
* An otherwise runnable thread of a process
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