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SubjectRe: multiprocessor kernel problem
Rusty,

Excellent! I applied the patch and netfilter is happy with 4 processors. Thank you and
thanks to everyone else who sent suggestions.


Roger



Rusty Russell wrote:

> 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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