On 02/07/2018 08:57 PM, David Miller wrote:
From: Grygorii Strashko <grygorii.strashko@xxxxxx> Date: Tue, 6 Feb 2018 19:17:06 -0600It 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@xxxxxx>Applied, thanks.
Thank you David. Could this be marked as stable material 4.9+? -- regards, -grygorii -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
