PCI: vmd: Prevent recursive locking on interrupt allocation
authorThomas Gleixner <tglx@linutronix.de>
Sun, 13 Feb 2022 13:54:05 +0000 (14:54 +0100)
committerThomas Gleixner <tglx@linutronix.de>
Mon, 21 Feb 2022 07:26:53 +0000 (08:26 +0100)
Tejas reported the following recursive locking issue:

 swapper/0/1 is trying to acquire lock:
 ffff8881074fd0a0 (&md->mutex){+.+.}-{3:3}, at: msi_get_virq+0x30/0xc0

 but task is already holding lock:
 ffff8881017cd6a0 (&md->mutex){+.+.}-{3:3}, at: __pci_enable_msi_range+0xf2/0x290

 stack backtrace:
  __mutex_lock+0x9d/0x920
  msi_get_virq+0x30/0xc0
  pci_irq_vector+0x26/0x30
  vmd_msi_init+0xcc/0x210
  msi_domain_alloc+0xbf/0x150
  msi_domain_alloc_irqs_descs_locked+0x3e/0xb0
  __pci_enable_msi_range+0x155/0x290
  pci_alloc_irq_vectors_affinity+0xba/0x100
  pcie_port_device_register+0x307/0x550
  pcie_portdrv_probe+0x3c/0xd0
  pci_device_probe+0x95/0x110

This is caused by the VMD MSI code which does a lookup of the Linux
interrupt number for an VMD managed MSI[X] vector. The lookup function
tries to acquire the already held mutex.

Avoid that by caching the Linux interrupt number at initialization time
instead of looking it up over and over.

Fixes: 82ff8e6b78fc ("PCI/MSI: Use msi_get_virq() in pci_get_vector()")
Reported-by: "Surendrakumar Upadhyay, TejaskumarX" <tejaskumarx.surendrakumar.upadhyay@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: "Surendrakumar Upadhyay, TejaskumarX" <tejaskumarx.surendrakumar.upadhyay@intel.com>
Cc: linux-pci@vger.kernel.org
Link: https://lore.kernel.org/r/87a6euub2a.ffs@tglx
drivers/pci/controller/vmd.c

index cc166c6..eb05cce 100644 (file)
@@ -99,11 +99,13 @@ struct vmd_irq {
  * @srcu:      SRCU struct for local synchronization.
  * @count:     number of child IRQs assigned to this vector; used to track
  *             sharing.
+ * @virq:      The underlying VMD Linux interrupt number
  */
 struct vmd_irq_list {
        struct list_head        irq_list;
        struct srcu_struct      srcu;
        unsigned int            count;
+       unsigned int            virq;
 };
 
 struct vmd_dev {
@@ -253,7 +255,6 @@ static int vmd_msi_init(struct irq_domain *domain, struct msi_domain_info *info,
        struct msi_desc *desc = arg->desc;
        struct vmd_dev *vmd = vmd_from_bus(msi_desc_to_pci_dev(desc)->bus);
        struct vmd_irq *vmdirq = kzalloc(sizeof(*vmdirq), GFP_KERNEL);
-       unsigned int index, vector;
 
        if (!vmdirq)
                return -ENOMEM;
@@ -261,10 +262,8 @@ static int vmd_msi_init(struct irq_domain *domain, struct msi_domain_info *info,
        INIT_LIST_HEAD(&vmdirq->node);
        vmdirq->irq = vmd_next_irq(vmd, desc);
        vmdirq->virq = virq;
-       index = index_from_irqs(vmd, vmdirq->irq);
-       vector = pci_irq_vector(vmd->dev, index);
 
-       irq_domain_set_info(domain, virq, vector, info->chip, vmdirq,
+       irq_domain_set_info(domain, virq, vmdirq->irq->virq, info->chip, vmdirq,
                            handle_untracked_irq, vmd, NULL);
        return 0;
 }
@@ -685,7 +684,8 @@ static int vmd_alloc_irqs(struct vmd_dev *vmd)
                        return err;
 
                INIT_LIST_HEAD(&vmd->irqs[i].irq_list);
-               err = devm_request_irq(&dev->dev, pci_irq_vector(dev, i),
+               vmd->irqs[i].virq = pci_irq_vector(dev, i);
+               err = devm_request_irq(&dev->dev, vmd->irqs[i].virq,
                                       vmd_irq, IRQF_NO_THREAD,
                                       vmd->name, &vmd->irqs[i]);
                if (err)
@@ -969,7 +969,7 @@ static int vmd_suspend(struct device *dev)
        int i;
 
        for (i = 0; i < vmd->msix_count; i++)
-               devm_free_irq(dev, pci_irq_vector(pdev, i), &vmd->irqs[i]);
+               devm_free_irq(dev, vmd->irqs[i].virq, &vmd->irqs[i]);
 
        return 0;
 }
@@ -981,7 +981,7 @@ static int vmd_resume(struct device *dev)
        int err, i;
 
        for (i = 0; i < vmd->msix_count; i++) {
-               err = devm_request_irq(dev, pci_irq_vector(pdev, i),
+               err = devm_request_irq(dev, vmd->irqs[i].virq,
                                       vmd_irq, IRQF_NO_THREAD,
                                       vmd->name, &vmd->irqs[i]);
                if (err)