diff options
author | Paolo Bonzini <pbonzini@redhat.com> | 2023-12-23 02:05:07 +0300 |
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committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-12-23 02:05:07 +0300 |
commit | ef5b28372c565128bdce7a59bc78402a8ce68e1b (patch) | |
tree | 77f549fcf73f8400a34e7a5d51548fafd1533644 /lib | |
parent | 5c2b2176ead1911d652b8848169bb44bdde75ca8 (diff) | |
parent | 4ad9843e1ea088bd2529290234c6c4c6374836a7 (diff) | |
download | linux-ef5b28372c565128bdce7a59bc78402a8ce68e1b.tar.xz |
Merge tag 'kvm-riscv-fixes-6.7-1' of https://github.com/kvm-riscv/linux into kvm-master
KVM/riscv fixes for 6.7, take #1
- Fix a race condition in updating external interrupt for
trap-n-emulated IMSIC swfile
- Fix print_reg defaults in get-reg-list selftest
Diffstat (limited to 'lib')
-rw-r--r-- | lib/group_cpus.c | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/lib/group_cpus.c b/lib/group_cpus.c index aa3f6815bb12..ee272c4cefcc 100644 --- a/lib/group_cpus.c +++ b/lib/group_cpus.c @@ -366,13 +366,25 @@ struct cpumask *group_cpus_evenly(unsigned int numgrps) if (!masks) goto fail_node_to_cpumask; - /* Stabilize the cpumasks */ - cpus_read_lock(); build_node_to_cpumask(node_to_cpumask); + /* + * Make a local cache of 'cpu_present_mask', so the two stages + * spread can observe consistent 'cpu_present_mask' without holding + * cpu hotplug lock, then we can reduce deadlock risk with cpu + * hotplug code. + * + * Here CPU hotplug may happen when reading `cpu_present_mask`, and + * we can live with the case because it only affects that hotplug + * CPU is handled in the 1st or 2nd stage, and either way is correct + * from API user viewpoint since 2-stage spread is sort of + * optimization. + */ + cpumask_copy(npresmsk, data_race(cpu_present_mask)); + /* grouping present CPUs first */ ret = __group_cpus_evenly(curgrp, numgrps, node_to_cpumask, - cpu_present_mask, nmsk, masks); + npresmsk, nmsk, masks); if (ret < 0) goto fail_build_affinity; nr_present = ret; @@ -387,15 +399,13 @@ struct cpumask *group_cpus_evenly(unsigned int numgrps) curgrp = 0; else curgrp = nr_present; - cpumask_andnot(npresmsk, cpu_possible_mask, cpu_present_mask); + cpumask_andnot(npresmsk, cpu_possible_mask, npresmsk); ret = __group_cpus_evenly(curgrp, numgrps, node_to_cpumask, npresmsk, nmsk, masks); if (ret >= 0) nr_others = ret; fail_build_affinity: - cpus_read_unlock(); - if (ret >= 0) WARN_ON(nr_present + nr_others < numgrps); |