Thread (16 messages) 16 messages, 3 authors, 2025-01-17
STALE550d

[PATCH iwl-net 1/4] igb: narrow scope of vfs_lock in SR-IOV cleanup

From: Wander Lairson Costa <hidden>
Date: 2024-12-04 11:43:33
Also in: intel-wired-lan, linux-rt-devel, lkml
Subsystem: intel ethernet drivers, networking drivers, the rest · Maintainers: Tony Nguyen, Przemek Kitszel, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds

The adapter->vfs_lock currently protects critical sections shared between
igb_disable_sriov() and igb_msg_task(). Since igb_msg_task() — which is
invoked solely by the igb_msix_other() ISR—only proceeds when
adapter->vfs_allocated_count > 0, we can reduce the lock scope further.

By moving the assignment adapter->vfs_allocated_count = 0 to the start of the
cleanup code in igb_disable_sriov(), we can restrict the spinlock protection
solely to this assignment. This change removes kfree() calls from within the
locked section, simplifying lock management.

Once kfree() is outside the vfs_lock scope, it becomes possible to safely
convert vfs_lock to a raw_spin_lock.

Signed-off-by: Wander Lairson Costa <redacted>
---
 drivers/net/ethernet/intel/igb/igb_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 08578980b6518..4ca25660e876e 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -3708,12 +3708,12 @@ static int igb_disable_sriov(struct pci_dev *pdev, bool reinit)
 			msleep(500);
 		}
 		spin_lock_irqsave(&adapter->vfs_lock, flags);
+		adapter->vfs_allocated_count = 0;
+		spin_unlock_irqrestore(&adapter->vfs_lock, flags);
 		kfree(adapter->vf_mac_list);
 		adapter->vf_mac_list = NULL;
 		kfree(adapter->vf_data);
 		adapter->vf_data = NULL;
-		adapter->vfs_allocated_count = 0;
-		spin_unlock_irqrestore(&adapter->vfs_lock, flags);
 		wr32(E1000_IOVCTL, E1000_IOVCTL_REUSE_VFQ);
 		wrfl();
 		msleep(100);
-- 
2.47.0
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