The following commit has been merged into the sched/core branch of tip: Commit-ID: f4291df103315a696f0b8c4f45ca8ae773c17441 Gitweb: https://git.kernel.org/tip/f4291df103315a696f0b8c4f45ca8ae773c17441 Author: Giovanni Gherdovich <ggherdovich@xxxxxxx> AuthorDate: Sun, 31 May 2020 20:24:53 +02:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Mon, 15 Jun 2020 14:10:02 +02:00 x86, sched: Bail out of frequency invariance if turbo_freq/base_freq gives 0 Be defensive against the case where the processor reports a base_freq larger than turbo_freq (the ratio would be zero). Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance") Signed-off-by: Giovanni Gherdovich <ggherdovich@xxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Link: https://lkml.kernel.org/r/20200531182453.15254-4-ggherdovich@xxxxxxx --- arch/x86/kernel/smpboot.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 20e1cea..518ac6b 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1977,6 +1977,7 @@ static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq) static bool intel_set_max_freq_ratio(void) { u64 base_freq, turbo_freq; + u64 turbo_ratio; if (slv_set_max_freq_ratio(&base_freq, &turbo_freq)) goto out; @@ -2010,9 +2011,15 @@ out: return false; } - arch_turbo_freq_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, - base_freq); + turbo_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, base_freq); + if (!turbo_ratio) { + pr_debug("Non-zero turbo and base frequencies led to a 0 ratio.\n"); + return false; + } + + arch_turbo_freq_ratio = turbo_ratio; arch_set_max_freq_ratio(turbo_disabled()); + return true; }
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