Commit 283e38db authored by Ben Hutchings's avatar Ben Hutchings Committed by David S. Miller

sh_eth: Fix serialisation of interrupt disable with interrupt & NAPI handlers

In order to stop the RX path accessing the RX ring while it's being
stopped or resized, we clear the interrupt mask (EESIPR) and then call
free_irq() or synchronise_irq().  This is insufficient because the
interrupt handler or NAPI poller may set EESIPR again after we clear
it.  Also, in sh_eth_set_ringparam() we currently don't disable NAPI
polling at all.

I could easily trigger a crash by running the loop:

   while ethtool -G eth0 rx 128 && ethtool -G eth0 rx 64; do echo -n .; done

and 'ping -f' toward the sh_eth port from another machine.

To fix this:
- Add a software flag (irq_enabled) to signal whether interrupts
  should be enabled
- In the interrupt handler, if the flag is clear then clear EESIPR
  and return
- In the NAPI poller, if the flag is clear then don't set EESIPR
- Set the flag before enabling interrupts in sh_eth_dev_init() and
  sh_eth_set_ringparam()
- Clear the flag and serialise with the interrupt and NAPI
  handlers before clearing EESIPR in sh_eth_close() and
  sh_eth_set_ringparam()

After this, I could run the loop for 100,000 iterations successfully.
Signed-off-by: default avatarBen Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 084236d8
......@@ -1316,8 +1316,10 @@ static int sh_eth_dev_init(struct net_device *ndev, bool start)
RFLR);
sh_eth_write(ndev, sh_eth_read(ndev, EESR), EESR);
if (start)
if (start) {
mdp->irq_enabled = true;
sh_eth_write(ndev, mdp->cd->eesipr_value, EESIPR);
}
/* PAUSE Prohibition */
val = (sh_eth_read(ndev, ECMR) & ECMR_DM) |
......@@ -1653,7 +1655,12 @@ static irqreturn_t sh_eth_interrupt(int irq, void *netdev)
if (intr_status & (EESR_RX_CHECK | cd->tx_check | cd->eesr_err_check))
ret = IRQ_HANDLED;
else
goto other_irq;
goto out;
if (!likely(mdp->irq_enabled)) {
sh_eth_write(ndev, 0, EESIPR);
goto out;
}
if (intr_status & EESR_RX_CHECK) {
if (napi_schedule_prep(&mdp->napi)) {
......@@ -1684,7 +1691,7 @@ static irqreturn_t sh_eth_interrupt(int irq, void *netdev)
sh_eth_error(ndev, intr_status);
}
other_irq:
out:
spin_unlock(&mdp->lock);
return ret;
......@@ -1712,6 +1719,7 @@ static int sh_eth_poll(struct napi_struct *napi, int budget)
napi_complete(napi);
/* Reenable Rx interrupts */
if (mdp->irq_enabled)
sh_eth_write(ndev, mdp->cd->eesipr_value, EESIPR);
out:
return budget - quota;
......@@ -1970,12 +1978,20 @@ static int sh_eth_set_ringparam(struct net_device *ndev,
if (netif_running(ndev)) {
netif_device_detach(ndev);
netif_tx_disable(ndev);
/* Disable interrupts by clearing the interrupt mask. */
/* Serialise with the interrupt handler and NAPI, then
* disable interrupts. We have to clear the
* irq_enabled flag first to ensure that interrupts
* won't be re-enabled.
*/
mdp->irq_enabled = false;
synchronize_irq(ndev->irq);
napi_synchronize(&mdp->napi);
sh_eth_write(ndev, 0x0000, EESIPR);
/* Stop the chip's Tx and Rx processes. */
sh_eth_write(ndev, 0, EDTRR);
sh_eth_write(ndev, 0, EDRRR);
synchronize_irq(ndev->irq);
/* Free all the skbuffs in the Rx queue. */
sh_eth_ring_free(ndev);
......@@ -2001,6 +2017,7 @@ static int sh_eth_set_ringparam(struct net_device *ndev,
return ret;
}
mdp->irq_enabled = true;
sh_eth_write(ndev, mdp->cd->eesipr_value, EESIPR);
/* Setting the Rx mode will start the Rx process. */
sh_eth_write(ndev, EDRRR_R, EDRRR);
......@@ -2184,7 +2201,13 @@ static int sh_eth_close(struct net_device *ndev)
netif_stop_queue(ndev);
/* Disable interrupts by clearing the interrupt mask. */
/* Serialise with the interrupt handler and NAPI, then disable
* interrupts. We have to clear the irq_enabled flag first to
* ensure that interrupts won't be re-enabled.
*/
mdp->irq_enabled = false;
synchronize_irq(ndev->irq);
napi_disable(&mdp->napi);
sh_eth_write(ndev, 0x0000, EESIPR);
/* Stop the chip's Tx and Rx processes. */
......@@ -2201,8 +2224,6 @@ static int sh_eth_close(struct net_device *ndev)
free_irq(ndev->irq, ndev);
napi_disable(&mdp->napi);
/* Free all the skbuffs in the Rx queue. */
sh_eth_ring_free(ndev);
......
......@@ -513,6 +513,7 @@ struct sh_eth_private {
u32 rx_buf_sz; /* Based on MTU+slack. */
int edmac_endian;
struct napi_struct napi;
bool irq_enabled;
/* MII transceiver section. */
u32 phy_id; /* PHY ID */
struct mii_bus *mii_bus; /* MDIO bus control */
......
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