From fade4dc49101e3b68fb375fd2b00d0ef1f31a36f Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Tue, 4 Sep 2012 14:26:03 +0200 Subject: s390/sysinfo,topology: fix cpu topology maximum nesting detection The maximum nesting of the cpu topology is evaluated when /proc/sysinfo is the first time read. This happens without a lock and a concurrent reader on a different cpu can see and use an invalid intermediate value. Besides the fact that this race is quite unlikely the worst thing that could happen is that /proc/sysinfo would contain bogus information about the machine's cpu topology. Nevertheless this should be fixed. So move the detection code to the early machine detection code and since now the value is early available use it in the topology code as well. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/topology.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) (limited to 'arch/s390/kernel/topology.c') diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c index fc957f2eef7c..80ca4ba759f6 100644 --- a/arch/s390/kernel/topology.c +++ b/arch/s390/kernel/topology.c @@ -251,12 +251,10 @@ static void update_cpu_core_map(void) void store_topology(struct sysinfo_15_1_x *info) { - int rc; - - rc = stsi(info, 15, 1, 3); - if (rc != -ENOSYS) - return; - stsi(info, 15, 1, 2); + if (topology_max_mnest >= 3) + stsi(info, 15, 1, 3); + else + stsi(info, 15, 1, 2); } int arch_update_cpu_topology(void) -- cgit v1.2.3