Messages in this thread | | | From | Lukasz Stelmach <> | Subject | Re: [PATCH net-next v16 3/3] net: ax88796c: ASIX AX88796C SPI Ethernet Adapter Driver | Date | Wed, 13 Oct 2021 23:14:20 +0200 |
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It was <2021-10-01 pią 15:39>, when Jakub Kicinski wrote: > On Wed, 29 Sep 2021 16:08:54 +0200 Łukasz Stelmach wrote: >> +static char *no_regs_list = "80018001,e1918001,8001a001,fc0d0000"; > > static const char ... > >> +static int >> +ax88796c_close(struct net_device *ndev) >> +{ >> + struct ax88796c_device *ax_local = to_ax88796c_device(ndev); >> + >> + netif_stop_queue(ndev); > > This can run concurrently with the work which restarts the queue. > You should take the mutex and purge the queue here, so that there > is no chance queue will get restarted by the work right after. >> + phy_stop(ndev->phydev); >> + >> + mutex_lock(&ax_local->spi_lock);
This was a bit tricky. The function now looks like this (details in the comments). In theory there is a chance of dropping a packet if the ax88796c_work() runs between phy_stop() and mutex_lock(), but I'd say the overall risk is negligible.
--8<---------------cut here---------------start------------->8--- static int ax88796c_close(struct net_device *ndev) { struct ax88796c_device *ax_local = to_ax88796c_device(ndev);
phy_stop(ndev->phydev);
/* We lock the mutex early not only to protect the device * against concurrent access, but also avoid waking up the * queue in ax88796c_work(). phy_stop() needs to be called * before because it locks the mutex to access SPI. */ mutex_lock(&ax_local->spi_lock);
netif_stop_queue(ndev);
/* No more work can be scheduled now. Make any pending work, * including one already waiting for the mutex to be unlocked, * NOP. */ clear_bit(EVENT_SET_MULTI, &ax_local->flags); clear_bit(EVENT_INTR, &ax_local->flags); clear_bit(EVENT_TX, &ax_local->flags);
/* Disable MAC interrupts */ AX_WRITE(&ax_local->ax_spi, IMR_MASKALL, P0_IMR); __skb_queue_purge(&ax_local->tx_wait_q); ax88796c_soft_reset(ax_local);
mutex_unlock(&ax_local->spi_lock);
cancel_work_sync(&ax_local->ax_work);
free_irq(ndev->irq, ndev);
return 0; } --8<---------------cut here---------------end--------------->8---
>> +MODULE_AUTHOR("ASIX"); > > You can drop this, author should be human.
I looked at diff --stat and decided it is OK to put my name there (-; -- Łukasz Stelmach Samsung R&D Institute Poland Samsung Electronics [unhandled content-type:application/pgp-signature] | |