diff options
| author | Russell King (Oracle) <rmk+kernel@armlinux.org.uk> | 2026-02-24 12:01:55 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-02-26 06:12:34 +0300 |
| commit | dd53a0e85969c6b2a5a4e4e46ba05b3187231017 (patch) | |
| tree | 6beabac26eb00277a68faa13460a0eae3f07f9fd | |
| parent | 819101c3c158f6e220be9a9ded3c48ff5701cf42 (diff) | |
| download | linux-dd53a0e85969c6b2a5a4e4e46ba05b3187231017.tar.xz | |
net: stmmac: fix transmit interrupt coalescing
The accounting for transmit frames does not count the descriptors
correctly. It uses:
tx_packets = (tx_q->cur_tx + 1) - first_tx;
however, these are indexes into a circular buffer, so cur_tx can be
less than first_tx, and when that happens, tx_packets becomes a very
large unsigned integer. When this is added to tx_q->tx_count_frames,
it has the effect of reducing the count of frames, possibly causing
it to also wrap to a very large unsigned integer.
Fix this by using CIRC_CNT() to calculate the number of descriptors
used.
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/E1vuoIl-0000000Aouz-0ttb@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 1a9fdde281f8..7bf3a8667999 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -4516,7 +4516,8 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev) tx_q->tx_skbuff_dma[tx_q->cur_tx].buf_type = STMMAC_TXBUF_T_SKB; /* Manage tx mitigation */ - tx_packets = (tx_q->cur_tx + 1) - first_tx; + tx_packets = CIRC_CNT(tx_q->cur_tx + 1, first_tx, + priv->dma_conf.dma_tx_size); tx_q->tx_count_frames += tx_packets; if ((skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) && priv->hwts_tx_en) @@ -4794,7 +4795,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev) * This approach takes care about the fragments: desc is the first * element in case of no SG. */ - tx_packets = (entry + 1) - first_tx; + tx_packets = CIRC_CNT(entry + 1, first_tx, priv->dma_conf.dma_tx_size); tx_q->tx_count_frames += tx_packets; if ((skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) && priv->hwts_tx_en) |