Commit 2fe9a5c6 authored by Andrew Banman's avatar Andrew Banman Committed by Ingo Molnar
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x86/platform/uv/BAU: Disable BAU on single hub configurations

The BAU confers no benefit to a UV system running with only one hub/socket.
Permanently disable the BAU driver if there are less than two hubs online
to avoid BAU overhead. We have observed failed boots on single-socket UV4
systems caused by BAU that are avoided with this patch.

Also, while at it, consolidate initialization error blocks and fix a
memory leak.
Signed-off-by: default avatarAndrew Banman <>
Acked-by: default avatarRuss Anderson <>
Acked-by: default avatarMike Travis <>
Cc: Linus Torvalds <>
Cc: Peter Zijlstra <>
Cc: Thomas Gleixner <>

[ Minor cleanups. ]
Signed-off-by: default avatarIngo Molnar <>
parent 0bc73048
......@@ -2221,13 +2221,17 @@ static int __init uv_bau_init(void)
else if (is_uv1_hub())
ops = uv1_bau_ops;
nuvhubs = uv_num_possible_blades();
if (nuvhubs < 2) {
pr_crit("UV: BAU disabled - insufficient hub count\n");
goto err_bau_disable;
for_each_possible_cpu(cur_cpu) {
mask = &per_cpu(uv_flush_tlb_mask, cur_cpu);
zalloc_cpumask_var_node(mask, GFP_KERNEL, cpu_to_node(cur_cpu));
nuvhubs = uv_num_possible_blades();
uv_base_pnode = 0x7fffffff;
for (uvhub = 0; uvhub < nuvhubs; uvhub++) {
cpus = uv_blade_nr_possible_cpus(uvhub);
......@@ -2240,9 +2244,8 @@ static int __init uv_bau_init(void)
if (init_per_cpu(nuvhubs, uv_base_pnode)) {
nobau_perm = 1;
return 0;
pr_crit("UV: BAU disabled - per CPU init failed\n");
goto err_bau_disable;
vector = UV_BAU_MESSAGE;
......@@ -2268,6 +2271,16 @@ static int __init uv_bau_init(void)
return 0;
free_cpumask_var(per_cpu(uv_flush_tlb_mask, cur_cpu));
nobau_perm = 1;
return -EINVAL;
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