On Thursday, July 28, 2016 3:18:26 PM CEST LABBE Corentin wrote: > > I will reworked locking and it seems that no locking is necessary. > I have added the following comment about the locking strategy: > > /* Locking strategy: > * RX queue does not need any lock since only sun8i_emac_poll() access it. > * (All other RX modifiers (ringparam/ndo_stop) disable NAPI and so sun8i_emac_poll()) > * TX queue is handled by sun8i_emac_xmit(), sun8i_emac_complete_xmit() and sun8i_emac_tx_timeout() > * (All other RX modifiers (ringparam/ndo_stop) disable NAPI and stop queue) > * > * sun8i_emac_xmit() could fire only once (netif_tx_lock) > * sun8i_emac_complete_xmit() could fire only once (called from NAPI) > * sun8i_emac_tx_timeout() could fire only once (netif_tx_lock) and couldnt > * race with sun8i_emac_xmit (due to netif_tx_lock) and with sun8i_emac_complete_xmit which disable NAPI. > * > * So only sun8i_emac_xmit and sun8i_emac_complete_xmit could fire at the same time. > * But they never could modify the same descriptors: > * - sun8i_emac_complete_xmit() will modify only descriptors with empty status > * - sun8i_emac_xmit() will modify only descriptors set to DCLEAN > * Proper memory barriers ensure that descriptor set to DCLEAN could not be > * modified latter by sun8i_emac_complete_xmit(). > * */ Sounds good, the comment is certainly very helpful here. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
