diff mbox series

[net,2/4] igb: introduce raw vfs_lock to igb_adapter

Message ID 20250204175243.810189-3-anthony.l.nguyen@intel.com (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series igb: fix igb_msix_other() handling for PREEMPT_RT | expand

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Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch warning WARNING: line length of 95 exceeds 80 columns WARNING: line length of 99 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 38 this patch: 38
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2025-02-05--00-00 (tests: 886)

Commit Message

Tony Nguyen Feb. 4, 2025, 5:52 p.m. UTC 
From: Wander Lairson Costa <wander@redhat.com>

This change adds a raw_spinlock for the vfs_lock to the
igb_adapter structure, enabling its use in both interrupt and
preemptible contexts. This is essential for upcoming modifications
to split igb_msg_task() into interrupt-safe and preemptible-safe
parts.

The motivation for this change stems from the need to modify
igb_msix_other() to run in interrupt context under PREEMPT_RT.
Currently, igb_msg_task() contains a code path that invokes
kcalloc() with the GFP_ATOMIC flag. However, on PREEMPT_RT,
GFP_ATOMIC is not honored, making it unsafe to call allocation
functions in interrupt context. By introducing this raw spinlock,
we can safely acquire the lock in both contexts, paving the way for
the necessary restructuring of igb_msg_task().

Signed-off-by: Wander Lairson Costa <wander@redhat.com>
Suggested-by: Clark Williams <williams@redhat.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/igb/igb.h      |  4 ++
 drivers/net/ethernet/intel/igb/igb_main.c | 51 ++++++++++++++++++++---
 2 files changed, 50 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
index 02f340280d20..30a188c5710e 100644
--- a/drivers/net/ethernet/intel/igb/igb.h
+++ b/drivers/net/ethernet/intel/igb/igb.h
@@ -673,6 +673,10 @@  struct igb_adapter {
 	struct vf_mac_filter *vf_mac_list;
 	/* lock for VF resources */
 	spinlock_t vfs_lock;
+#ifdef CONFIG_PREEMPT_RT
+	/* Used to lock VFS in interrupt context under PREEMPT_RT */
+	raw_spinlock_t raw_vfs_lock;
+#endif
 };
 
 /* flags controlling PTP/1588 function */
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 77571f6fdbfd..4e75c88f6214 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -3657,6 +3657,47 @@  static int igb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	return err;
 }
 
+#ifdef CONFIG_PREEMPT_RT
+static __always_inline void vfs_lock_init(struct igb_adapter *adapter)
+{
+	spin_lock_init(&adapter->vfs_lock);
+	raw_spin_lock_init(&adapter->raw_vfs_lock);
+}
+
+static __always_inline void vfs_lock_irqsave(struct igb_adapter *adapter,
+					     unsigned long *flags)
+{
+	/*
+	 * Remember that under PREEMPT_RT spin_lock_irqsave
+	 * ignores the flags parameter
+	 */
+	spin_lock_irqsave(&adapter->vfs_lock, *flags);
+	raw_spin_lock_irqsave(&adapter->raw_vfs_lock, *flags);
+}
+
+static __always_inline void vfs_unlock_irqrestore(struct igb_adapter *adapter,
+						  unsigned long flags)
+{
+	raw_spin_unlock_irqrestore(&adapter->raw_vfs_lock, flags);
+	spin_unlock_irqrestore(&adapter->vfs_lock, flags);
+}
+#else
+static __always_inline void vfs_lock_init(struct igb_adapter *adapter)
+{
+	spin_lock_init(&adapter->vfs_lock);
+}
+
+static __always_inline void vfs_lock_irqsave(struct igb_adapter *adapter, unsigned long *flags)
+{
+	spin_lock_irqsave(&adapter->vfs_lock, *flags);
+}
+
+static __always_inline void vfs_unlock_irqrestore(struct igb_adapter *adapter, unsigned long flags)
+{
+	spin_unlock_irqrestore(&adapter->vfs_lock, flags);
+}
+#endif
+
 #ifdef CONFIG_PCI_IOV
 static int igb_sriov_reinit(struct pci_dev *dev)
 {
@@ -3707,9 +3748,9 @@  static int igb_disable_sriov(struct pci_dev *pdev, bool reinit)
 			pci_disable_sriov(pdev);
 			msleep(500);
 		}
-		spin_lock_irqsave(&adapter->vfs_lock, flags);
+		vfs_lock_irqsave(adapter, &flags);
 		adapter->vfs_allocated_count = 0;
-		spin_unlock_irqrestore(&adapter->vfs_lock, flags);
+		vfs_unlock_irqrestore(adapter, flags);
 		kfree(adapter->vf_mac_list);
 		adapter->vf_mac_list = NULL;
 		kfree(adapter->vf_data);
@@ -4042,7 +4083,7 @@  static int igb_sw_init(struct igb_adapter *adapter)
 	spin_lock_init(&adapter->stats64_lock);
 
 	/* init spinlock to avoid concurrency of VF resources */
-	spin_lock_init(&adapter->vfs_lock);
+	vfs_lock_init(adapter);
 #ifdef CONFIG_PCI_IOV
 	switch (hw->mac.type) {
 	case e1000_82576:
@@ -8078,7 +8119,7 @@  static void igb_msg_task(struct igb_adapter *adapter)
 	unsigned long flags;
 	u32 vf;
 
-	spin_lock_irqsave(&adapter->vfs_lock, flags);
+	vfs_lock_irqsave(adapter, &flags);
 	for (vf = 0; vf < adapter->vfs_allocated_count; vf++) {
 		/* process any reset requests */
 		if (!igb_check_for_rst(hw, vf))
@@ -8092,7 +8133,7 @@  static void igb_msg_task(struct igb_adapter *adapter)
 		if (!igb_check_for_ack(hw, vf))
 			igb_rcv_ack_from_vf(adapter, vf);
 	}
-	spin_unlock_irqrestore(&adapter->vfs_lock, flags);
+	vfs_unlock_irqrestore(adapter, flags);
 }
 
 /**