On Wed, Oct 02, 2013 at 12:29:04PM +0200, Alexander Gordeev wrote: > This series is against "next" branch in Bjorn's repo: > git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git > > Currently pci_enable_msi_block() and pci_enable_msix() interfaces > return a error code in case of failure, 0 in case of success and a > positive value which indicates the number of MSI-X/MSI interrupts > that could have been allocated. The latter value should be passed > to a repeated call to the interfaces until a failure or success: > > > for (i = 0; i < FOO_DRIVER_MAXIMUM_NVEC; i++) > adapter->msix_entries[i].entry = i; > > while (nvec >= FOO_DRIVER_MINIMUM_NVEC) { > rc = pci_enable_msix(adapter->pdev, > adapter->msix_entries, nvec); > if (rc > 0) > nvec = rc; > else > return rc; > } > > return -ENOSPC; > > > This technique proved to be confusing and error-prone. Vast share > of device drivers simply fail to follow the described guidelines. To clarify "Vast share of device drivers": - 58 drivers call pci_enable_msix() - 24 try a single allocation and then fallback to MSI/LSI - 19 use the loop style allocation as above - 14 try an allocation, and if it fails retry once - 1 incorrectly continues when pci_enable_msix() returns > 0 So 33 drivers (> 50%) successfully make use of the "confusing and error-prone" return value. Another 24 happily ignore it, which is also entirely fine. And yes, one is buggy, so obviously the interface is too complex. Thanks drivers/ntb/ntb_hw.c cheers -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html