Linux IOMMU Development
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From: Yi Liu <yi.l.liu@intel.com>
To: jgg@nvidia.com, kevin.tian@intel.com
Cc: nicolinc@nvidia.com, yi.l.liu@intel.com,
	baolu.lu@linux.intel.com, iommu@lists.linux.dev
Subject: [PATCH 2/2] iommufd: Balance veventq->num_events inc/dec
Date: Mon, 24 Mar 2025 05:00:34 -0700	[thread overview]
Message-ID: <20250324120034.5940-3-yi.l.liu@intel.com> (raw)
In-Reply-To: <20250324120034.5940-1-yi.l.liu@intel.com>

iommufd_veventq_fops_read() decrements veventq->num_events when a vevent
is read out. However, the report path ony increments veventq->num_events
for normal events. To be balanced, make the read path decrement num_events
only for normal vevents.

Fixes: e36ba5ab808e ("iommufd: Add IOMMUFD_OBJ_VEVENTQ and IOMMUFD_CMD_VEVENTQ_ALLOC")
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 drivers/iommu/iommufd/eventq.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/iommufd/eventq.c b/drivers/iommu/iommufd/eventq.c
index 4c43ace8c725..f39cf0797347 100644
--- a/drivers/iommu/iommufd/eventq.c
+++ b/drivers/iommu/iommufd/eventq.c
@@ -385,7 +385,8 @@ static ssize_t iommufd_veventq_fops_read(struct file *filep, char __user *buf,
 			break;
 		}
 		spin_lock(&eventq->lock);
-		veventq->num_events--;
+		if (!vevent_for_lost_events_header(cur))
+			veventq->num_events--;
 		spin_unlock(&eventq->lock);
 		done += cur->data_len;
 		kfree(cur);
-- 
2.34.1


  parent reply	other threads:[~2025-03-24 12:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-03-24 12:00 [PATCH 0/2] Two fixes to vevent path Yi Liu
2025-03-24 12:00 ` [PATCH 1/2] iommufd: Initialize the flags of vevent in iommufd_viommu_report_event() Yi Liu
2025-03-24 14:04   ` Nicolin Chen
2025-03-24 12:00 ` Yi Liu [this message]
2025-03-24 14:07   ` [PATCH 2/2] iommufd: Balance veventq->num_events inc/dec Nicolin Chen
2025-03-25 13:35 ` [PATCH 0/2] Two fixes to vevent path Jason Gunthorpe

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