[PATCH v3 1/3] can: skb: make echo skb freeing safe in any IRQ context

[Cunhao Lu]

can_put_echo_skb() can be called with hardware interrupts disabled. Its
direct drop paths use kfree_skb(), while can_create_echo_skb() uses
kfree_skb() when cloning fails and consume_skb() after a successful clone.
None of these helpers is safe in every IRQ context.

Use dev_kfree_skb_any() for all drop paths and dev_consume_skb_any() when
consuming a successfully cloned skb. This preserves the respective skb drop
and consumed semantics regardless of the caller IRQ context.

Signed-off-by: Cunhao Lu <1579567540@xxxxxx>
---
Changes in v3:
- Cover can_create_echo_skb() clone failure and successful-clone consume
  paths with IRQ-context-independent helpers.
---
 drivers/net/can/dev/skb.c | 4 ++--
 include/linux/can/skb.h   | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/dev/skb.c b/drivers/net/can/dev/skb.c
index 95fcdc1026f8..d7b5a5d17ff2 100644
--- a/drivers/net/can/dev/skb.c
+++ b/drivers/net/can/dev/skb.c
@@ -62,7 +62,7 @@ int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
 	    (skb->protocol != htons(ETH_P_CAN) &&
 	     skb->protocol != htons(ETH_P_CANFD) &&
 	     skb->protocol != htons(ETH_P_CANXL))) {
-		kfree_skb(skb);
+		dev_kfree_skb_any(skb);
 		return 0;
 	}
 
@@ -90,7 +90,7 @@ int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
 	} else {
 		/* locking problem with netif_stop_queue() ?? */
 		netdev_err(dev, "%s: BUG! echo_skb %d is occupied!\n", __func__, idx);
-		kfree_skb(skb);
+		dev_kfree_skb_any(skb);
 		return -EBUSY;
 	}
 
diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h
index a70a02967071..78c5870e2f9a 100644
--- a/include/linux/can/skb.h
+++ b/include/linux/can/skb.h
@@ -76,12 +76,12 @@ static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
 
 	nskb = skb_clone(skb, GFP_ATOMIC);
 	if (unlikely(!nskb)) {
-		kfree_skb(skb);
+		dev_kfree_skb_any(skb);
 		return NULL;
 	}
 
 	can_skb_set_owner(nskb, skb->sk);
-	consume_skb(skb);
+	dev_consume_skb_any(skb);
 	return nskb;
 }
 

-- 
2.34.1