diff mbox series

[bpf,2/2] xsk: rollback reservation at NETDEV_TX_BUSY

Message ID 20201214152757.7632-3-magnus.karlsson@gmail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series xsk: fix two bugs in the SKB Tx path | expand

Checks

Context Check Description
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netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 20 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Magnus Karlsson Dec. 14, 2020, 3:27 p.m. UTC 
From: Magnus Karlsson <magnus.karlsson@intel.com>

Rollback the reservation in the completion ring when we get a
NETDEV_TX_BUSY. When this error is received from the driver, we are
supposed to let the user application retry the transmit again. And in
order to do this, we need to roll back the failed send so it can be
retried. Unfortunately, we did not cancel the reservation we had made
in the completion ring. By not doing this, we actually make the
completion ring one entry smaller per NETDEV_TX_BUSY error we get, and
after enough of these errors the completion ring will be of size zero
and transmit will stop working.

Fix this by cancelling the reservation when we get a NETDEV_TX_BUSY
error.

Fixes: 642e450b6b59 ("xsk: Do not discard packet when NETDEV_TX_BUSY")
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Reported-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 net/xdp/xsk.c       | 3 +++
 net/xdp/xsk_queue.h | 5 +++++
 2 files changed, 8 insertions(+)
diff mbox series

Patch

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 42cb5f94d49e..2587583a6be9 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -428,6 +428,9 @@  static int xsk_generic_xmit(struct sock *sk)
 		if  (err == NETDEV_TX_BUSY) {
 			/* Tell user-space to retry the send */
 			skb->destructor = sock_wfree;
+			spin_lock_irqsave(&xs->pool->cq_lock, flags);
+			xskq_prod_cancel(xs->pool->cq);
+			spin_unlock_irqrestore(&xs->pool->cq_lock, flags);
 			/* Free skb without triggering the perf drop trace */
 			consume_skb(skb);
 			err = -EAGAIN;
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 9e71b9f27679..ef6de0fb4e31 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -286,6 +286,11 @@  static inline bool xskq_prod_is_full(struct xsk_queue *q)
 	return !free_entries;
 }
 
+static inline void xskq_prod_cancel(struct xsk_queue *q)
+{
+	q->cached_prod--;
+}
+
 static inline int xskq_prod_reserve(struct xsk_queue *q)
 {
 	if (xskq_prod_is_full(q))