linux-kernel - [PATCH] amd/iommu: fix logic bug in amd_iommu_report_page

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Date:   Sat, 31 Jul 2021 12:26:37 -0700
From:   Luigi Rizzo <lrizzo@...gle.com>
To:     Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org,
        Joerg Roedel <joro@...tes.org>,
        David Rientjes <rientjes@...gle.com>, rizzo.unipi@...il.com,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc:     Luigi Rizzo <lrizzo@...gle.com>
Subject: [PATCH] amd/iommu: fix logic bug in amd_iommu_report_page_fault()

amd_iommu_report_page_fault() has two print paths, depending on whether or
not it can find a pci device. But the code erroneously enters the second
path if the rate limiter in the first path triggers:
  if (dev_data && ratelimit(A)) { A; } else if (ratelimit(B)) { B; }
The correct code should be
  if (dev_data) { if (ratelimit(A)) { A;} } else if (ratelimit(B)) { B; }

Signed-off-by: Luigi Rizzo <lrizzo@...gle.com>
---
 drivers/iommu/amd/iommu.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 811a49a95d04..38b4aff70800 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -480,9 +480,11 @@ static void amd_iommu_report_page_fault(u16 devid, u16 domain_id,
 	if (pdev)
 		dev_data = dev_iommu_priv_get(&pdev->dev);
 
-	if (dev_data && __ratelimit(&dev_data->rs)) {
-		pci_err(pdev, "Event logged [IO_PAGE_FAULT domain=0x%04x address=0x%llx flags=0x%04x]\n",
-			domain_id, address, flags);
+	if (dev_data) {
+		if (__ratelimit(&dev_data->rs)) {
+			pci_err(pdev, "Event logged [IO_PAGE_FAULT domain=0x%04x address=0x%llx flags=0x%04x]\n",
+				domain_id, address, flags);
+		}
 	} else if (printk_ratelimit()) {
 		pr_err("Event logged [IO_PAGE_FAULT device=%02x:%02x.%x domain=0x%04x address=0x%llx flags=0x%04x]\n",
 			PCI_BUS_NUM(devid), PCI_SLOT(devid), PCI_FUNC(devid),
-- 
2.32.0.554.ge1b32706d8-goog