2019-11-23 14:21:47

by Chuhong Yuan

Subject: [PATCH net v3] net: macb: add missed tasklet_kill

This driver forgets to kill tasklet in remove.
Add the call to fix it.

Fixes: 032dc41ba6e2 ("net: macb: Handle HRESP error")
Signed-off-by: Chuhong Yuan <[email protected]>
---
Changes in v3:
- Add fixes tag and target 'net'.

drivers/net/ethernet/cadence/macb_main.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 1e1b774e1953..2ec416098fa3 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -4383,6 +4383,7 @@ static int macb_remove(struct platform_device *pdev)

if (dev) {
bp = netdev_priv(dev);
+ tasklet_kill(&bp->hresp_err_tasklet);
if (dev->phydev)
phy_disconnect(dev->phydev);
mdiobus_unregister(bp->mii_bus);
--
2.24.0

2019-11-25 02:23:01

by Jakub Kicinski

Subject: Re: [PATCH net v3] net: macb: add missed tasklet_kill

On Sat, 23 Nov 2019 22:19:18 +0800, Chuhong Yuan wrote:
> This driver forgets to kill tasklet in remove.
> Add the call to fix it.
>
> Fixes: 032dc41ba6e2 ("net: macb: Handle HRESP error")
> Signed-off-by: Chuhong Yuan <[email protected]>

I think this leaves a race condition, as far as I can tell
tasklet_kill() just kills the currently scheduled tasklet,
but doesn't prevent it from being scheduled again. If the
interrupt fires just after the tasklet_kill() call the tasklet
will be scheduled back in. I think you'd need to mask the interrupt
(through the IDR register?) or just put the tasklet_kill() call after
unregister_netdev(), because AFAICT closing the netdev disables all
irqs.

> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 1e1b774e1953..2ec416098fa3 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -4383,6 +4383,7 @@ static int macb_remove(struct platform_device *pdev)
>
> if (dev) {
> bp = netdev_priv(dev);
> + tasklet_kill(&bp->hresp_err_tasklet);
> if (dev->phydev)
> phy_disconnect(dev->phydev);
> mdiobus_unregister(bp->mii_bus);