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SubjectRe: multiprocessor kernel problem
Date
In message <m2elzp3uiq.fsf@euler.axel.nom> you write:
> yes, but is it a dual machine or is it an N-way SMP with N > 2? the
> other guy with iptables/SMP problems also has a quad box. could this
> perhaps be a problem only when you have more than two processors?

Yes, hacked my machine to think it had 4 cpus, and boom.

There are two problems:
(1) initialization of multiple tables was wrong, and
(2) iterating through tables should not use cpu_number_map (doesn't
matter on X86 though).

Please try attached patch.

Thanks,
Rusty,
--
Hacking time.
--- working-2.4.0-test11-5/net/ipv4/netfilter/ip_tables.c.~1~ Sat Aug 12 00:23:40 2000
+++ working-2.4.0-test11-5/net/ipv4/netfilter/ip_tables.c Mon Dec 4 16:12:44 2000
@@ -89,10 +89,8 @@
unsigned int hook_entry[NF_IP_NUMHOOKS];
unsigned int underflow[NF_IP_NUMHOOKS];

- char padding[SMP_ALIGN((NF_IP_NUMHOOKS*2+2)*sizeof(unsigned int))];
-
/* ipt_entry tables: one per CPU */
- char entries[0];
+ char entries[0] __attribute__((aligned(SMP_CACHE_BYTES)));
};

static LIST_HEAD(ipt_target);
@@ -101,7 +99,7 @@
#define ADD_COUNTER(c,b,p) do { (c).bcnt += (b); (c).pcnt += (p); } while(0)

#ifdef CONFIG_SMP
-#define TABLE_OFFSET(t,p) (SMP_ALIGN((t)->size)*cpu_number_map(p))
+#define TABLE_OFFSET(t,p) (SMP_ALIGN((t)->size)*(p))
#else
#define TABLE_OFFSET(t,p) 0
#endif
@@ -283,7 +281,8 @@
read_lock_bh(&table->lock);
IP_NF_ASSERT(table->valid_hooks & (1 << hook));
table_base = (void *)table->private->entries
- + TABLE_OFFSET(table->private, smp_processor_id());
+ + TABLE_OFFSET(table->private,
+ cpu_number_map(smp_processor_id()));
e = get_entry(table_base, table->private->hook_entry[hook]);

#ifdef CONFIG_NETFILTER_DEBUG
@@ -860,7 +859,7 @@

/* And one copy for every other CPU */
for (i = 1; i < smp_num_cpus; i++) {
- memcpy(newinfo->entries + SMP_ALIGN(newinfo->size*i),
+ memcpy(newinfo->entries + SMP_ALIGN(newinfo->size)*i,
newinfo->entries,
SMP_ALIGN(newinfo->size));
}
@@ -1359,7 +1358,7 @@
int ret;
struct ipt_table_info *newinfo;
static struct ipt_table_info bootstrap
- = { 0, 0, { 0 }, { 0 }, { }, { } };
+ = { 0, 0, { 0 }, { 0 }, { } };

MOD_INC_USE_COUNT;
newinfo = vmalloc(sizeof(struct ipt_table_info)
-
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