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Subject[PATCH 5.4 088/104] net/sonic: Clear interrupt flags immediately
Date
From: Finn Thain <fthain@telegraphics.com.au>

commit 5fedabf5a70be26b19d7520f09f12a62274317c6 upstream.

The chip can change a packet's descriptor status flags at any time.
However, an active interrupt flag gets cleared rather late. This
allows a race condition that could theoretically lose an interrupt.
Fix this by clearing asserted interrupt flags immediately.

Fixes: efcce839360f ("[PATCH] macsonic/jazzsonic network drivers update")
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/ethernet/natsemi/sonic.c | 28 ++++++----------------------
1 file changed, 6 insertions(+), 22 deletions(-)

--- a/drivers/net/ethernet/natsemi/sonic.c
+++ b/drivers/net/ethernet/natsemi/sonic.c
@@ -304,10 +304,11 @@ static irqreturn_t sonic_interrupt(int i
}

do {
+ SONIC_WRITE(SONIC_ISR, status); /* clear the interrupt(s) */
+
if (status & SONIC_INT_PKTRX) {
netif_dbg(lp, intr, dev, "%s: packet rx\n", __func__);
sonic_rx(dev); /* got packet(s) */
- SONIC_WRITE(SONIC_ISR, SONIC_INT_PKTRX); /* clear the interrupt */
}

if (status & SONIC_INT_TXDN) {
@@ -362,7 +363,6 @@ static irqreturn_t sonic_interrupt(int i
if (freed_some || lp->tx_skb[entry] == NULL)
netif_wake_queue(dev); /* The ring is no longer full */
lp->cur_tx = entry;
- SONIC_WRITE(SONIC_ISR, SONIC_INT_TXDN); /* clear the interrupt */
}

/*
@@ -372,42 +372,31 @@ static irqreturn_t sonic_interrupt(int i
netif_dbg(lp, rx_err, dev, "%s: rx fifo overrun\n",
__func__);
lp->stats.rx_fifo_errors++;
- SONIC_WRITE(SONIC_ISR, SONIC_INT_RFO); /* clear the interrupt */
}
if (status & SONIC_INT_RDE) {
netif_dbg(lp, rx_err, dev, "%s: rx descriptors exhausted\n",
__func__);
lp->stats.rx_dropped++;
- SONIC_WRITE(SONIC_ISR, SONIC_INT_RDE); /* clear the interrupt */
}
if (status & SONIC_INT_RBAE) {
netif_dbg(lp, rx_err, dev, "%s: rx buffer area exceeded\n",
__func__);
lp->stats.rx_dropped++;
- SONIC_WRITE(SONIC_ISR, SONIC_INT_RBAE); /* clear the interrupt */
}

/* counter overruns; all counters are 16bit wide */
- if (status & SONIC_INT_FAE) {
+ if (status & SONIC_INT_FAE)
lp->stats.rx_frame_errors += 65536;
- SONIC_WRITE(SONIC_ISR, SONIC_INT_FAE); /* clear the interrupt */
- }
- if (status & SONIC_INT_CRC) {
+ if (status & SONIC_INT_CRC)
lp->stats.rx_crc_errors += 65536;
- SONIC_WRITE(SONIC_ISR, SONIC_INT_CRC); /* clear the interrupt */
- }
- if (status & SONIC_INT_MP) {
+ if (status & SONIC_INT_MP)
lp->stats.rx_missed_errors += 65536;
- SONIC_WRITE(SONIC_ISR, SONIC_INT_MP); /* clear the interrupt */
- }

/* transmit error */
- if (status & SONIC_INT_TXER) {
+ if (status & SONIC_INT_TXER)
if (SONIC_READ(SONIC_TCR) & SONIC_TCR_FU)
netif_dbg(lp, tx_err, dev, "%s: tx fifo underrun\n",
__func__);
- SONIC_WRITE(SONIC_ISR, SONIC_INT_TXER); /* clear the interrupt */
- }

/* bus retry */
if (status & SONIC_INT_BR) {
@@ -416,13 +405,8 @@ static irqreturn_t sonic_interrupt(int i
/* ... to help debug DMA problems causing endless interrupts. */
/* Bounce the eth interface to turn on the interrupt again. */
SONIC_WRITE(SONIC_IMR, 0);
- SONIC_WRITE(SONIC_ISR, SONIC_INT_BR); /* clear the interrupt */
}

- /* load CAM done */
- if (status & SONIC_INT_LCD)
- SONIC_WRITE(SONIC_ISR, SONIC_INT_LCD); /* clear the interrupt */
-
status = SONIC_READ(SONIC_ISR) & SONIC_IMR_DEFAULT;
} while (status);


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