On Thu, Jul 20, 2017 at 01:47:50PM +0200, Ingo Molnar wrote: > > * Andrew Banman <[email protected]> wrote: > > > 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. > > > > Signed-off-by: Andrew Banman <[email protected]> > > Acked-by: Russ Anderson <[email protected]> > > Acked-by: Mike Travis <[email protected]> > > --- > > arch/x86/platform/uv/tlb_uv.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c > > index 2511a28..88216cc 100644 > > --- a/arch/x86/platform/uv/tlb_uv.c > > +++ b/arch/x86/platform/uv/tlb_uv.c > > @@ -2251,6 +2251,12 @@ static int __init uv_bau_init(void) > > } > > > > nuvhubs = uv_num_possible_blades(); > > + if (nuvhubs < 2) { > > + pr_crit("UV: BAU disabled - insufficient hub count\n"); > > + set_bau_off(); > > + nobau_perm = 1; > > + return 0; > > + } > > Yeah, could you structure the error paths in this function in a bit more > organized > fashion? It has two similar error handling blocks: > > > pr_crit("UV: BAU disabled - insufficient hub count\n"); > set_bau_off(); > nobau_perm = 1; > return 0; > > ... > > set_bau_off(); > nobau_perm = 1; > return 0; > > which could be consolidated via the usual goto exception construct: > > if (nuvhubs < 2) { > pr_crit("UV: BAU disabled - insufficient hub count\n"); > goto err_disable_bau; > } > ... > > if (init_per_cpu(nuvhubs, uv_base_pnode)) > pr_crit("UV: BAU disabled - per CPU init failed\n"); > goto err_disable_bau; > } > > ... > return 0; > > err_disable_bau: > > set_bau_off(); > nobau_perm = 1; > return 0; > > Note that I added an error message to the second case as well. > > Plus, in the error case you might want to use a 'return -EINVAL;' instead of > return 0, or so?
I agree with your suggestions, and I'm happy to make the changes. > > Plus plus, there's probably a (mild) memory leak in the error paths, can the > cpumasks be free_cpumask_var() freed - or are they still required even if BAU > is > disabled? In the case of nobau_perm=1 they can be freed. I will include that in the next version. > > Thanks, > > Ingo Thank you! I'll have the next version out shortly. Andrew
