Messages in this thread | | | Subject | Re: [PATCH] net: ethernet: ti: cpsw: fix net watchdog timeout | From | Grygorii Strashko <> | Date | Thu, 8 Feb 2018 10:04:31 -0600 |
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On 02/07/2018 08:57 PM, David Miller wrote: > From: Grygorii Strashko <grygorii.strashko@ti.com> > Date: Tue, 6 Feb 2018 19:17:06 -0600 > >> It was discovered that simple program which indefinitely sends 200b UDP >> packets and runs on TI AM574x SoC (SMP) under RT Kernel triggers network >> watchdog timeout in TI CPSW driver (<6 hours run). The network watchdog >> timeout is triggered due to race between cpsw_ndo_start_xmit() and >> cpsw_tx_handler() [NAPI] >> >> cpsw_ndo_start_xmit() >> if (unlikely(!cpdma_check_free_tx_desc(txch))) { >> txq = netdev_get_tx_queue(ndev, q_idx); >> netif_tx_stop_queue(txq); >> >> ^^ as per [1] barier has to be used after set_bit() otherwise new value >> might not be visible to other cpus >> } >> >> cpsw_tx_handler() >> if (unlikely(netif_tx_queue_stopped(txq))) >> netif_tx_wake_queue(txq); >> >> and when it happens ndev TX queue became disabled forever while driver's HW >> TX queue is empty. >> >> Fix this, by adding smp_mb__after_atomic() after netif_tx_stop_queue() >> calls and double check for free TX descriptors after stopping ndev TX queue >> - if there are free TX descriptors wake up ndev TX queue. >> >> [1] https://www.kernel.org/doc/html/latest/core-api/atomic_ops.html >> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> > > Applied, thanks. >
Thank you David.
Could this be marked as stable material 4.9+?
-- regards, -grygorii
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