On 2/14/2022 2:26 PM, Jason Wang wrote:

在 2022/2/3 下午3:27, Zhu Lingshan 写道:

quoted

This commit implements a MSIX vector allocation helper
for vqs and config interrupts.

Signed-off-by: Zhu Lingshan <redacted>
---
  drivers/vdpa/ifcvf/ifcvf_main.c | 35 +++++++++++++++++++++++++++++++--
  1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c 

b/drivers/vdpa/ifcvf/ifcvf_main.c
index d1a6b5ab543c..44c89ab0b6da 100644

--- a/drivers/vdpa/ifcvf/ifcvf_main.c
+++ b/drivers/vdpa/ifcvf/ifcvf_main.c

@@ -58,14 +58,45 @@ static void ifcvf_free_irq(struct ifcvf_adapter 

*adapter, int queues)
      ifcvf_free_irq_vectors(pdev);
  }
  +/* ifcvf MSIX vectors allocator, this helper tries to allocate
+ * vectors for all virtqueues and the config interrupt.
+ * It returns the number of allocated vectors, negative
+ * return value when fails.
+ */
+static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
+{
+    struct pci_dev *pdev = adapter->pdev;
+    struct ifcvf_hw *vf = &adapter->vf;
+    int max_intr, ret;
+
+    /* all queues and config interrupt  */
+    max_intr = vf->nr_vring + 1;
+    ret = pci_alloc_irq_vectors(pdev, 1, max_intr, PCI_IRQ_MSIX | 
PCI_IRQ_AFFINITY);
+
+    if (ret < 0) {
+        IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
+        return ret;
+    }
+
+    if (ret < max_intr)
+        IFCVF_INFO(pdev,
+               "Requested %u vectors, however only %u allocated, 
lower performance\n",
+               max_intr, ret);
+
+    return ret;
+}
+
  static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
  {
      struct pci_dev *pdev = adapter->pdev;
      struct ifcvf_hw *vf = &adapter->vf;
-    int vector, i, ret, irq;
+    int vector, nvectors, i, ret, irq;
      u16 max_intr;
  -    /* all queues and config interrupt  */
+    nvectors = ifcvf_alloc_vectors(adapter);
+    if (!(nvectors > 0))
+        return nvectors;

Why not simply checking by using nvectors <= 0? If ifcvf_alloc_vectors 
can return 0 this breaks the ifcvf_request_irq() caller's assumption.

It can return zero if no vectors allocated, then ifcvf_request_irq 
fails. For sure I can use <=0

Thanks!

quoted

+
      max_intr = vf->nr_vring + 1;
        ret = pci_alloc_irq_vectors(pdev, max_intr,

So irq is allocated twice here?

Oh, it is a rebasing problem, I should move the deleting line here from 
the next patch.

Thanks

Thanks