Date: Sat, 20 Feb 1999 22:48:04 -0500 (EST) From: Brian Feldman <green@unixhelp.org> To: current@freebsd.org Subject: one SysV bug/fix, how many more Message-ID: <Pine.BSF.4.05.9902202240420.17317-100000@janus.syracuse.net>
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Two things:
1. I've been looking at sysv_shm.c, and shouldn't there be a ton of splvm()ing
going on which isn't? It seems that there are quite a few race conditions
that never showed up before because there was no support for sharing certain
parts of proc (p_vmspace etc.) For that matter, does any of kern_exit.c:exit1()
need to be spl()d? It sure seems like it to me. Along with other parts of
kern_exit.c, and many other things having to do with refcnt's. Is it just my
paranoia, or have I got this spl concept correct?
2. I sent a previous message, but got no reply at all; the patch included
follows here, and was made to fix a bug where non-removeable shm segments
existed.
--- src/sys/kern/sysv_shm.c.old Sat Feb 20 11:36:15 1999
+++ src/sys/kern/sysv_shm.c Sat Feb 20 11:46:19 1999
@@ -596,10 +596,13 @@
shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
- if (shmmap_s->shmid != -1)
+ if (shmmap_s->shmid != -1 &&
+ --shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch < 1)
shm_delete_mapping(p, shmmap_s);
- free((caddr_t)p->p_vmspace->vm_shm, M_SHM);
- p->p_vmspace->vm_shm = NULL;
+ if (p->p_vmspace->vm_refcnt == 1) {
+ free((caddr_t)p->p_vmspace->vm_shm, M_SHM);
+ p->p_vmspace->vm_shm = NULL;
+ }
}
void
--- src/sys/kern/kern_exit.c.old Sat Feb 20 11:36:02 1999
+++ src/sys/kern/kern_exit.c Sat Feb 20 11:46:22 1999
@@ -206,6 +206,10 @@
/* The next two chunks should probably be moved to vmspace_exit. */
vm = p->p_vmspace;
+
+ if (vm->vm_shm)
+ shmexit(p);
+
/*
* Release user portion of address space.
* This releases references to vnodes,
@@ -215,8 +219,6 @@
* may be mapped within that space also.
*/
if (vm->vm_refcnt == 1) {
- if (vm->vm_shm)
- shmexit(p);
pmap_remove_pages(vmspace_pmap(vm), VM_MIN_ADDRESS,
VM_MAXUSER_ADDRESS);
(void) vm_map_remove(&vm->vm_map, VM_MIN_ADDRESS,
Brian Feldman _ __ ___ ___ ___
green@unixhelp.org _ __ ___ | _ ) __| \
http://www.freebsd.org/ _ __ ___ ____ | _ \__ \ |) |
FreeBSD: The Power to Serve! _ __ ___ ____ _____ |___/___/___/
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