Messages in this thread Patch in this message | | | Date | Sun, 21 Jan 2018 12:36:36 +0100 (CET) | From | Thomas Gleixner <> | Subject | [GIT pull] irq fix for 4.15 |
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Linus,
please pull the latest irq-urgent-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git irq-urgent-for-linus
A single fix for the new matrix allocator to prevent vector exhaustion by certain network drivers which allocate gazillions of unused vectors which cannot be put into reservation mode due to MSI and the lack of MSI entry masking. The fix/workaround is to spread the vectors across CPUs by searching the supplied target CPU mask for the CPU with the smallest number of allocated vectors.
Thanks,
tglx
------------------> Thomas Gleixner (1): irq/matrix: Spread interrupts on allocation
kernel/irq/matrix.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/kernel/irq/matrix.c b/kernel/irq/matrix.c index 0ba0dd8863a7..5187dfe809ac 100644 --- a/kernel/irq/matrix.c +++ b/kernel/irq/matrix.c @@ -321,15 +321,23 @@ void irq_matrix_remove_reserved(struct irq_matrix *m) int irq_matrix_alloc(struct irq_matrix *m, const struct cpumask *msk, bool reserved, unsigned int *mapped_cpu) { - unsigned int cpu; + unsigned int cpu, best_cpu, maxavl = 0; + struct cpumap *cm; + unsigned int bit; + best_cpu = UINT_MAX; for_each_cpu(cpu, msk) { - struct cpumap *cm = per_cpu_ptr(m->maps, cpu); - unsigned int bit; + cm = per_cpu_ptr(m->maps, cpu); - if (!cm->online) + if (!cm->online || cm->available <= maxavl) continue; + best_cpu = cpu; + maxavl = cm->available; + } + + if (maxavl) { + cm = per_cpu_ptr(m->maps, best_cpu); bit = matrix_alloc_area(m, cm, 1, false); if (bit < m->alloc_end) { cm->allocated++; @@ -338,8 +346,8 @@ int irq_matrix_alloc(struct irq_matrix *m, const struct cpumask *msk, m->global_available--; if (reserved) m->global_reserved--; - *mapped_cpu = cpu; - trace_irq_matrix_alloc(bit, cpu, m, cm); + *mapped_cpu = best_cpu; + trace_irq_matrix_alloc(bit, best_cpu, m, cm); return bit; } }
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