Messages in this thread | | | Date | Thu, 20 Jul 2017 13:47:50 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86/platform/uv/BAU: disable BAU on single hub configurations |
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* Andrew Banman <abanman@hpe.com> 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 <abanman@hpe.com> > Acked-by: Russ Anderson <rja@hpe.com> > Acked-by: Mike Travis <mike.travis@hpe.com> > --- > 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?
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?
Thanks,
Ingo
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