Re: [PATCH net 1/4] NTB: ntb_transport: Recycle TX entries before client callbacks
From: Dave Jiang <dave.jiang@intel.com>
Date: 2026-08-19 21:16:13
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On 8/16/26 10:35 PM, Koichiro Den wrote:
ntb_tx_copy_callback() invokes the client callback before returning the
entry to tx_free_q. The callback may wake a stopped client queue, only
for the next enqueue to find no local entry and return -EBUSY. The window
is narrow, but the retry is unnecessary.
Save the callback data and length, then return the entry to tx_free_q
before invoking the client. A completion callback then means both the
client buffer and transport entry are ready for reuse.
Fixes: fce8a7bb5b4b ("PCI-Express Non-Transparent Bridge Support")
Cc: stable@vger.kernel.org
Signed-off-by: Koichiro Den <redacted>Reviewed-by: Dave Jiang <dave.jiang@intel.com>
quoted hunk ↗ jump to hunk
--- drivers/ntb/ntb_transport.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-)diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c index f59f926d4bfa..e92b96f4afad 100644 --- a/drivers/ntb/ntb_transport.c +++ b/drivers/ntb/ntb_transport.c@@ -1719,9 +1719,16 @@ static void ntb_transport_rxc_db(unsigned long data) static void ntb_tx_copy_callback(void *data, const struct dmaengine_result *res) { + struct ntb_payload_header __iomem *hdr; struct ntb_queue_entry *entry = data; - struct ntb_transport_qp *qp = entry->qp; - struct ntb_payload_header __iomem *hdr = entry->tx_hdr; + struct ntb_transport_qp *qp; + unsigned int len; + void *cb_data; + + qp = entry->qp; + hdr = entry->tx_hdr; + cb_data = entry->cb_data; + len = entry->len; /* we need to check DMA results if we are using DMA */ if (res) {@@ -1768,15 +1775,13 @@ static void ntb_tx_copy_callback(void *data, * "link down" or similar. Since no payload is being sent in these * cases, there is nothing to add to the completion queue. */ - if (entry->len > 0) { - qp->tx_bytes += entry->len; - - if (qp->tx_handler) - qp->tx_handler(qp, qp->cb_data, entry->cb_data, - entry->len); - } + if (len > 0) + qp->tx_bytes += len; ntb_list_add(&qp->ntb_tx_free_q_lock, &entry->entry, &qp->tx_free_q); + + if (len > 0 && qp->tx_handler) + qp->tx_handler(qp, qp->cb_data, cb_data, len); } static void ntb_memcpy_tx_on_stack(struct ntb_queue_entry *entry, void __iomem *offset)