From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
To: sergei.shtylyov@gmail.com, davem@davemloft.net, kuba@kernel.org
Cc: netdev@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Subject: [PATCH 2/2] sh_eth: Fix descriptor counters' conditions
Date: Tue, 27 Jul 2021 17:21:47 +0900 [thread overview]
Message-ID: <20210727082147.270734-3-yoshihiro.shimoda.uh@renesas.com> (raw)
In-Reply-To: <20210727082147.270734-1-yoshihiro.shimoda.uh@renesas.com>
The descriptor counters ({cur,dirty}_[rt]x) acts as free counters
so that conditions are possible to be incorrect when a left value
was overflowed.
So, for example, sh_eth_tx_free() could not free any descriptors
because the following condition was checked as a signed value,
and then "NETDEV WATCHDOG" happened:
for (; mdp->cur_tx - mdp->dirty_tx > 0; mdp->dirty_tx++) {
To fix the issue, add get_num_desc() to calculate numbers of
remaining descriptors.
Fixes: 86a74ff21a7a ("net: sh_eth: add support for Renesas SuperH Ethernet")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
drivers/net/ethernet/renesas/sh_eth.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 840478692a37..7c9445ad684b 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -1227,6 +1227,14 @@ static const struct mdiobb_ops bb_ops = {
.get_mdio_data = sh_get_mdio,
};
+static u32 get_num_desc(u32 from, u32 subtract)
+{
+ if (from >= subtract)
+ return from - subtract;
+
+ return U32_MAX - subtract + 1 + from;
+}
+
/* free Tx skb function */
static int sh_eth_tx_free(struct net_device *ndev, bool sent_only)
{
@@ -1236,7 +1244,7 @@ static int sh_eth_tx_free(struct net_device *ndev, bool sent_only)
int entry;
bool sent;
- for (; mdp->cur_tx - mdp->dirty_tx > 0; mdp->dirty_tx++) {
+ for (; get_num_desc(mdp->cur_tx, mdp->dirty_tx) > 0; mdp->dirty_tx++) {
entry = mdp->dirty_tx % mdp->num_tx_ring;
txdesc = &mdp->tx_ring[entry];
sent = !(txdesc->status & cpu_to_le32(TD_TACT));
@@ -1587,7 +1595,7 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota)
struct sh_eth_rxdesc *rxdesc;
int entry = mdp->cur_rx % mdp->num_rx_ring;
- int boguscnt = (mdp->dirty_rx + mdp->num_rx_ring) - mdp->cur_rx;
+ int boguscnt = get_num_desc(mdp->dirty_rx, mdp->cur_rx) + mdp->num_rx_ring;
int limit;
struct sk_buff *skb;
u32 desc_status;
@@ -1667,7 +1675,7 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota)
}
/* Refill the Rx ring buffers. */
- for (; mdp->cur_rx - mdp->dirty_rx > 0; mdp->dirty_rx++) {
+ for (; get_num_desc(mdp->cur_rx, mdp->dirty_rx) > 0; mdp->dirty_rx++) {
entry = mdp->dirty_rx % mdp->num_rx_ring;
rxdesc = &mdp->rx_ring[entry];
/* The size of the buffer is 32 byte boundary. */
@@ -2499,7 +2507,7 @@ static netdev_tx_t sh_eth_start_xmit(struct sk_buff *skb,
unsigned long flags;
spin_lock_irqsave(&mdp->lock, flags);
- if ((mdp->cur_tx - mdp->dirty_tx) >= (mdp->num_tx_ring - 4)) {
+ if (get_num_desc(mdp->cur_tx, mdp->dirty_tx) >= (mdp->num_tx_ring - 4)) {
if (!sh_eth_tx_free(ndev, true)) {
netif_warn(mdp, tx_queued, ndev, "TxFD exhausted.\n");
netif_stop_queue(ndev);
--
2.25.1
next prev parent reply other threads:[~2021-07-27 8:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-27 8:21 [PATCH 0/2] ravb and sh_eth: Fix descriptor counters' conditions Yoshihiro Shimoda
2021-07-27 8:21 ` [PATCH 1/2] ravb: " Yoshihiro Shimoda
2021-07-27 8:55 ` Ulrich Hecht
2021-07-27 9:13 ` Ulrich Hecht
2021-07-27 9:52 ` Yoshihiro Shimoda
2021-07-27 8:21 ` Yoshihiro Shimoda [this message]
2021-07-29 4:59 ` [PATCH 0/2] ravb and sh_eth: " Yoshihiro Shimoda
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