Re: [PATCH v4 5/5] net: mana: Allocate MSI-X vectors dynamically
From: Simon Horman <horms@kernel.org>
Date: 2025-05-28 18:52:45
Also in:
linux-pci, linux-rdma, lkml, netdev
On Tue, May 27, 2025 at 08:59:03AM -0700, Shradha Gupta wrote:
Currently, the MANA driver allocates MSI-X vectors statically based on MANA_MAX_NUM_QUEUES and num_online_cpus() values and in some cases ends up allocating more vectors than it needs. This is because, by this time we do not have a HW channel and do not know how many IRQs should be allocated. To avoid this, we allocate 1 MSI-X vector during the creation of HWC and after getting the value supported by hardware, dynamically add the remaining MSI-X vectors. Signed-off-by: Shradha Gupta <redacted> Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
...
quoted hunk ↗ jump to hunk
+static int mana_gd_setup_irqs(struct pci_dev *pdev, int nvec) +{ + struct gdma_context *gc = pci_get_drvdata(pdev); + struct gdma_irq_context *gic; + int *irqs, *start_irqs, irq; + unsigned int cpu; + int err, i; + + cpus_read_lock(); + + irqs = kmalloc_array(nvec, sizeof(int), GFP_KERNEL); + if (!irqs) { err = -ENOMEM; - goto free_irq_array; + goto free_irq_vector; } for (i = 0; i < nvec; i++) { - gic = &gc->irq_contexts[i]; + gic = kzalloc(sizeof(*gic), GFP_KERNEL); + if (!gic) { + err = -ENOMEM; + goto free_irq; + } + gic->handler = mana_gd_process_eq_events; INIT_LIST_HEAD(&gic->eq_list); spin_lock_init(&gic->lock);@@ -1418,69 +1498,128 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev) snprintf(gic->name, MANA_IRQ_NAME_SZ, "mana_q%d@pci:%s", i - 1, pci_name(pdev)); - irq = pci_irq_vector(pdev, i); - if (irq < 0) { - err = irq; - goto free_irq; + irqs[i] = pci_irq_vector(pdev, i); + if (irqs[i] < 0) { + err = irqs[i]; + goto free_current_gic; } - if (!i) { - err = request_irq(irq, mana_gd_intr, 0, gic->name, gic); - if (err) - goto free_irq; - - /* If number of IRQ is one extra than number of online CPUs, - * then we need to assign IRQ0 (hwc irq) and IRQ1 to - * same CPU. - * Else we will use different CPUs for IRQ0 and IRQ1. - * Also we are using cpumask_local_spread instead of - * cpumask_first for the node, because the node can be - * mem only. - */ - if (start_irq_index) { - cpu = cpumask_local_spread(i, gc->numa_node); - irq_set_affinity_and_hint(irq, cpumask_of(cpu)); - } else { - irqs[start_irq_index] = irq; - } - } else { - irqs[i - start_irq_index] = irq; - err = request_irq(irqs[i - start_irq_index], mana_gd_intr, 0, - gic->name, gic); - if (err) - goto free_irq; - } + err = request_irq(irqs[i], mana_gd_intr, 0, gic->name, gic); + if (err) + goto free_current_gic;
Jumping to free_current_gic will free start_irqs. However, start_irqs isn't initialised until a few lines below. Flagged by Smatch.
+
+ xa_store(&gc->irq_contexts, i, gic, GFP_KERNEL);
}
- err = irq_setup(irqs, nvec - start_irq_index, gc->numa_node, false);
+ /* If number of IRQ is one extra than number of online CPUs,
+ * then we need to assign IRQ0 (hwc irq) and IRQ1 to
+ * same CPU.
+ * Else we will use different CPUs for IRQ0 and IRQ1.
+ * Also we are using cpumask_local_spread instead of
+ * cpumask_first for the node, because the node can be
+ * mem only.
+ */
+ start_irqs = irqs;
+ if (nvec > num_online_cpus()) {
+ cpu = cpumask_local_spread(0, gc->numa_node);
+ irq_set_affinity_and_hint(irqs[0], cpumask_of(cpu));
+ irqs++;
+ nvec -= 1;
+ }
+
+ err = irq_setup(irqs, nvec, gc->numa_node, false);
if (err)
goto free_irq;
- gc->max_num_msix = nvec;
- gc->num_msix_usable = nvec;
cpus_read_unlock();
- kfree(irqs);
+ kfree(start_irqs);
return 0;
+free_current_gic:
+ kfree(gic);
free_irq:
- for (j = i - 1; j >= 0; j--) {
- irq = pci_irq_vector(pdev, j);
- gic = &gc->irq_contexts[j];
+ for (i -= 1; i >= 0; i--) {
+ irq = pci_irq_vector(pdev, i);
+ gic = xa_load(&gc->irq_contexts, i);
+ if (WARN_ON(!gic))
+ continue;
irq_update_affinity_hint(irq, NULL);
free_irq(irq, gic);
+ xa_erase(&gc->irq_contexts, i);
+ kfree(gic);
}
- kfree(gc->irq_contexts);
- gc->irq_contexts = NULL;
-free_irq_array:
- kfree(irqs);
+ kfree(start_irqs);
free_irq_vector:
cpus_read_unlock();
- pci_free_irq_vectors(pdev);
return err;
}...