Re: [PATCH RFC 46/77] mlx4: Update MSI/MSI-X interrupts enablement code
From: Jack Morgenstein <hidden>
Date: 2013-10-03 08:27:14
Also in:
linux-mips, linux-pci, linux-rdma, linux-s390, linux-scsi, linuxppc-dev, lkml, netdev
On Wed, 2 Oct 2013 12:49:02 +0200 Alexander Gordeev [off-list ref] wrote: UPDATING THIS REPLY. Your change log confused me. The change below is not from a "recent re-design", it is required due to an earlier patch in this patch set.
From the log, I assumed that the change you are talking about is already
upstream. I will re-review. -Jack NACK. This change does not do anything logically as far as I can tell. pci_enable_msix in the current upstream kernel itself calls pci_msix_table_size. The current code yields the same resultswill as the code suggested below. (i.e., the suggested code has no effect on optimality). BTW, pci_msix_table_size never returns a value < 0 (if msix is not enabled, it returns 0 for the table size), so the (err < 0) check here is not correct. (I also do not like using "err" here anyway for the value returned by pci_msix_table_size(). There is no error here, and it is simply confusing. -Jack
quoted hunk ↗ jump to hunk
As result of recent re-design of the MSI/MSI-X interrupts enabling pattern this driver has to be updated to use the new technique to obtain a optimal number of MSI/MSI-X interrupts required. Signed-off-by: Alexander Gordeev <redacted> --- drivers/net/ethernet/mellanox/mlx4/main.c | 17 ++++++++--------- 1 files changed, 8 insertions(+), 9 deletions(-)diff --git a/drivers/net/ethernet/mellanox/mlx4/main.cb/drivers/net/ethernet/mellanox/mlx4/main.c index 60c9f4f..377a5ea 100644 --- a/drivers/net/ethernet/mellanox/mlx4/main.c+++ b/drivers/net/ethernet/mellanox/mlx4/main.c@@ -1852,8 +1852,16 @@ static void mlx4_enable_msi_x(struct mlx4_dev*dev) int i; if (msi_x) { + err = pci_msix_table_size(dev->pdev); + if (err < 0) + goto no_msi; + + /* Try if at least 2 vectors are available */ nreq = min_t(int, dev->caps.num_eqs - dev->caps.reserved_eqs, nreq); + nreq = min_t(int, nreq, err); + if (nreq < 2) + goto no_msi; entries = kcalloc(nreq, sizeof *entries, GFP_KERNEL); if (!entries)@@ -1862,17 +1870,8 @@ static void mlx4_enable_msi_x(struct mlx4_dev*dev) for (i = 0; i < nreq; ++i) entries[i].entry = i; - retry: err = pci_enable_msix(dev->pdev, entries, nreq); if (err) { - /* Try again if at least 2 vectors are available */ - if (err > 1) { - mlx4_info(dev, "Requested %d vectors, " - "but only %d MSI-X vectors available, " - "trying again\n", nreq, err); - nreq = err; - goto retry; - } kfree(entries); goto no_msi; }