Re: [PATCH RFC 07/77] PCI/MSI: Re-design MSI/MSI-X interrupts enablement pattern
From: Tejun Heo <tj@kernel.org>
Date: 2013-10-07 18:18:01
Also in:
linux-ide, linux-mips, linux-nvme, linux-pci, linux-rdma, linux-s390, linux-scsi, lkml, netdev
Hello, On Wed, Oct 02, 2013 at 12:48:23PM +0200, Alexander Gordeev wrote:
+static int foo_driver_enable_msi(struct foo_adapter *adapter, int nvec)
+{
+ rc = pci_get_msi_cap(adapter->pdev);
+ if (rc < 0)
+ return rc;
+
+ nvec = min(nvec, rc);
+ if (nvec < FOO_DRIVER_MINIMUM_NVEC) {
+ return -ENOSPC;
+
+ rc = pci_enable_msi_block(adapter->pdev, nvec);
+ return rc;
+}If there are many which duplicate the above pattern, it'd probably be worthwhile to provide a helper? It's usually a good idea to reduce the amount of boilerplate code in drivers.
static int foo_driver_enable_msix(struct foo_adapter *adapter, int nvec)
{
+ rc = pci_msix_table_size(adapter->pdev);
+ if (rc < 0)
+ return rc;
+
+ nvec = min(nvec, rc);
+ if (nvec < FOO_DRIVER_MINIMUM_NVEC) {
+ return -ENOSPC;
+
+ for (i = 0; i < nvec; i++)
+ adapter->msix_entries[i].entry = i;
+
+ rc = pci_enable_msix(adapter->pdev, adapter->msix_entries, nvec);
+ return rc;
}Ditto.
quoted hunk ↗ jump to hunk
@@ -975,7 +951,7 @@ int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec) if (nr_entries < 0) return nr_entries; if (nvec > nr_entries) - return nr_entries; + return -EINVAL; /* Check for any invalid entries */ for (i = 0; i < nvec; i++) {
If we do things this way, it breaks all drivers using this interface until they're converted, right? Also, it probably isn't the best idea to flip the behavior like this as this can go completely unnoticed (no compiler warning or anything, the same function just behaves differently). Maybe it'd be a better idea to introduce a simpler interface that most can be converted to? Thanks. -- tejun