The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 784a0830377d0761834e385975bc46861fea9fa0 Gitweb: https://git.kernel.org/tip/784a0830377d0761834e385975bc46861fea9fa0 Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Sun, 30 Aug 2020 19:07:53 +02:00 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Sun, 30 Aug 2020 19:17:28 +02:00 genirq/matrix: Deal with the sillyness of for_each_cpu() on UP Most of the CPU mask operations behave the same way, but for_each_cpu() and it's variants ignore the cpumask argument and claim that CPU0 is always in the mask. This is historical, inconsistent and annoying behaviour. The matrix allocator uses for_each_cpu() and can be called on UP with an empty cpumask. The calling code does not expect that this succeeds but until commit e027fffff799 ("x86/irq: Unbreak interrupt affinity setting") this went unnoticed. That commit added a WARN_ON() to catch cases which move an interrupt from one vector to another on the same CPU. The warning triggers on UP. Add a check for the cpumask being empty to prevent this. Fixes: 2f75d9e1c905 ("genirq: Implement bitmap matrix allocator") Reported-by: kernel test robot <rong.a.chen@xxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx --- kernel/irq/matrix.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/irq/matrix.c b/kernel/irq/matrix.c index 30cc217..651a4ad 100644 --- a/kernel/irq/matrix.c +++ b/kernel/irq/matrix.c @@ -380,6 +380,13 @@ int irq_matrix_alloc(struct irq_matrix *m, const struct cpumask *msk, unsigned int cpu, bit; struct cpumap *cm; + /* + * Not required in theory, but matrix_find_best_cpu() uses + * for_each_cpu() which ignores the cpumask on UP . + */ + if (cpumask_empty(msk)) + return -EINVAL; + cpu = matrix_find_best_cpu(m, msk); if (cpu == UINT_MAX) return -ENOSPC;
