From: Frank Li <Frank.li@nxp.com>
To: Koichiro Den <den@valinux.co.jp>
Cc: "Jon Mason" <jdmason@kudzu.us>,
"Dave Jiang" <dave.jiang@intel.com>,
"Allen Hubbe" <allenbh@gmail.com>,
"Manivannan Sadhasivam" <mani@kernel.org>,
"Krzysztof Wilczyński" <kwilczynski@kernel.org>,
"Kishon Vijay Abraham I" <kishon@kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Jerome Brunet" <jbrunet@baylibre.com>,
"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Niklas Cassel" <cassel@kernel.org>,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
ntb@lists.linux.dev
Subject: Re: [PATCH v4 04/12] PCI: endpoint: pci-epf-vntb: Reject unusable doorbell counts
Date: Thu, 14 May 2026 14:55:57 -0400 [thread overview]
Message-ID: <agYavbv1asHSK1RV@lizhi-Precision-Tower-5810> (raw)
In-Reply-To: <20260513024923.451765-5-den@valinux.co.jp>
On Wed, May 13, 2026 at 11:49:15AM +0900, Koichiro Den wrote:
> pci-epf-vntb reserves slot 0 for link events and keeps slot 1 unused for
> legacy layout compatibility. A db_count smaller than MIN_DB_COUNT leaves
> no usable doorbell slot after those reservations.
>
> Reject such configurations when configuring interrupts.
>
> While at it, move MAX_DB_COUNT next to MIN_DB_COUNT. They are used as a
> pair in the range check, and keeping them together makes the valid doorbell
> range easier to read.
>
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> ---
Reviewed-by: Frank Li <Frank.Li@nxp.com>
> Changes since v3:
> - New patch.
>
> drivers/pci/endpoint/functions/pci-epf-vntb.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> index d31e2eee0869..818ae5999976 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> @@ -67,7 +67,6 @@ static struct workqueue_struct *kpcintb_workqueue;
> #define NTB_MW_OFFSET 2
> #define DB_COUNT_MASK GENMASK(15, 0)
> #define MSIX_ENABLE BIT(16)
> -#define MAX_DB_COUNT 32
> #define MAX_MW 4
>
> /* Limit per-work execution to avoid monopolizing kworker on doorbell storms. */
> @@ -89,6 +88,9 @@ enum epf_irq_slot {
> EPF_IRQ_DB_START,
> };
>
> +#define MIN_DB_COUNT (EPF_IRQ_DB_START + 1)
> +#define MAX_DB_COUNT 32
> +
> /*
> * +--------------------------------------------------+ Base
> * | |
> @@ -512,9 +514,9 @@ static int epf_ntb_configure_interrupt(struct epf_ntb *ntb)
> return -EINVAL;
> }
>
> - if (!ntb->db_count || ntb->db_count > MAX_DB_COUNT) {
> - dev_err(dev, "DB count %d out of range (1 - %d)\n",
> - ntb->db_count, MAX_DB_COUNT);
> + if (ntb->db_count < MIN_DB_COUNT || ntb->db_count > MAX_DB_COUNT) {
> + dev_err(dev, "DB count %d out of range (%d - %d)\n",
> + ntb->db_count, MIN_DB_COUNT, MAX_DB_COUNT);
> return -EINVAL;
> }
>
> --
> 2.51.0
>
next prev parent reply other threads:[~2026-05-14 18:56 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-13 2:49 [PATCH v4 00/12] PCI: endpoint: pci-epf-vntb / NTB: epf: Enable per-doorbell bit handling Koichiro Den
2026-05-13 2:49 ` [PATCH v4 01/12] PCI: endpoint: pci-epf-vntb: Document legacy MSI doorbell offset Koichiro Den
2026-05-13 2:49 ` [PATCH v4 02/12] PCI: endpoint: pci-epf-vntb: Defer pci_epc_raise_irq() out of atomic context Koichiro Den
2026-05-14 18:53 ` Frank Li
2026-05-13 2:49 ` [PATCH v4 03/12] PCI: endpoint: pci-epf-vntb: Report 0-based doorbell vector via ntb_db_event() Koichiro Den
2026-05-13 2:49 ` [PATCH v4 04/12] PCI: endpoint: pci-epf-vntb: Reject unusable doorbell counts Koichiro Den
2026-05-14 18:55 ` Frank Li [this message]
2026-05-13 2:49 ` [PATCH v4 05/12] PCI: endpoint: pci-epf-vntb: Guard configfs writes after EPC attach Koichiro Den
2026-05-14 18:57 ` Frank Li
2026-05-13 2:49 ` [PATCH v4 06/12] PCI: endpoint: pci-epf-vntb: Exclude reserved slots from db_valid_mask Koichiro Den
2026-05-13 2:49 ` [PATCH v4 07/12] PCI: endpoint: pci-epf-vntb: Implement db_vector_count/mask for doorbells Koichiro Den
2026-05-14 19:02 ` Frank Li
2026-05-13 2:49 ` [PATCH v4 08/12] NTB: epf: Document legacy doorbell slot offset in ntb_epf_peer_db_set() Koichiro Den
2026-05-13 2:49 ` [PATCH v4 09/12] NTB: epf: Make db_valid_mask cover only real doorbell bits Koichiro Den
2026-05-26 22:21 ` Dave Jiang
2026-05-13 2:49 ` [PATCH v4 10/12] NTB: epf: Report 0-based doorbell vector via ntb_db_event() Koichiro Den
2026-05-14 19:03 ` Frank Li
2026-05-26 22:28 ` Dave Jiang
2026-05-13 2:49 ` [PATCH v4 11/12] NTB: epf: Fix doorbell bitmask and IRQ vector handling Koichiro Den
2026-05-14 19:06 ` Frank Li
2026-05-26 22:36 ` Dave Jiang
2026-05-13 2:49 ` [PATCH v4 12/12] NTB: epf: Implement db_vector_count/mask for doorbells Koichiro Den
2026-05-26 22:47 ` Dave Jiang
2026-06-23 16:31 ` Bjorn Helgaas
2026-06-24 1:35 ` Koichiro Den
2026-05-19 14:42 ` [PATCH v4 00/12] PCI: endpoint: pci-epf-vntb / NTB: epf: Enable per-doorbell bit handling Manivannan Sadhasivam
2026-05-19 21:29 ` Dave Jiang
2026-05-21 6:29 ` Koichiro Den
2026-05-26 14:45 ` Dave Jiang
2026-05-26 15:56 ` Koichiro Den
2026-05-26 16:27 ` Dave Jiang
2026-05-27 9:09 ` Manivannan Sadhasivam
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