From: Daire McNamara <daire.mcnamara@xxxxxxxxxxxxx> Clear MSI bit in ISTATUS register after reading it before handling individual MSI bits This fixes a potential race condition pointed out by Bjorn Helgaas: https://lore.kernel.org/linux-pci/20220127202000.GA126335@bhelgaas/ Fixes: 6f15a9c9f941 ("PCI: microchip: Add Microchip PolarFire PCIe controller driver") Signed-off-by: Daire McNamara <daire.mcnamara@xxxxxxxxxxxxx> --- Adding linux-pci mailing list drivers/pci/controller/pcie-microchip-host.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/drivers/pci/controller/pcie-microchip-host.c b/drivers/pci/controller/pcie-microchip-host.c index 29d8e81e4181..da8e3fdc97b3 100644 --- a/drivers/pci/controller/pcie-microchip-host.c +++ b/drivers/pci/controller/pcie-microchip-host.c @@ -416,6 +416,7 @@ static void mc_handle_msi(struct irq_desc *desc) status = readl_relaxed(bridge_base_addr + ISTATUS_LOCAL); if (status & PM_MSI_INT_MSI_MASK) { + writel_relaxed(status & PM_MSI_INT_MSI_MASK, bridge_base_addr + ISTATUS_LOCAL); status = readl_relaxed(bridge_base_addr + ISTATUS_MSI); for_each_set_bit(bit, &status, msi->num_vectors) { ret = generic_handle_domain_irq(msi->dev_domain, bit); @@ -432,13 +433,8 @@ static void mc_msi_bottom_irq_ack(struct irq_data *data) void __iomem *bridge_base_addr = port->axi_base_addr + MC_PCIE_BRIDGE_ADDR; u32 bitpos = data->hwirq; - unsigned long status; writel_relaxed(BIT(bitpos), bridge_base_addr + ISTATUS_MSI); - status = readl_relaxed(bridge_base_addr + ISTATUS_MSI); - if (!status) - writel_relaxed(BIT(PM_MSI_INT_MSI_SHIFT), - bridge_base_addr + ISTATUS_LOCAL); } static void mc_compose_msi_msg(struct irq_data *data, struct msi_msg *msg) -- 2.25.1
