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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?xJAhPuUGR0Urkh0I6NJXIuWo4lGb4khDKN3nqdmUr4p13vOmDhssFgilAv7x?= =?us-ascii?Q?k1094GypVB/AHc2eJu0Ke0czUJNOQbTuZ36/X7LlQvh92lEk9kOlsfoVF/uj?= =?us-ascii?Q?ZB87SAtt0LJpOjGh5VoU6uophwJ5EEm02M16tmB57meczPrNb/m4m60fGBJP?= =?us-ascii?Q?tSFRu/+iZAn0OKgWW6hmTgQEWSm1A+xVg67nYsJX4ovzzFNRtk4f+yuMg59L?= =?us-ascii?Q?J0k9vFhVGakZisaLIE2TiivaH6C46Ms5n0rOTSQ5mxWpz82jJrfaKrM6AaIQ?= =?us-ascii?Q?PMjSjaScaEtU6HRmWMLsaSFpZ6AnDHgXE4y9AANtTw0cgxmNyUZgBODB1ija?= =?us-ascii?Q?s+2ZtSQLbI80X+Uk62ht0zhRJjP5j/FKoWIwNOK5TVm4RrZh+vrt9pV21oYV?= =?us-ascii?Q?pbw94K3il4Tv7PFLuBwG22SICiCeWmaFODzu6icMxvJPnvzCR0XfEdBamYQK?= =?us-ascii?Q?YejUhh7ktYUe+QgRo3WoM9ggYrdMydT0PyayhUzhTGXAiBij9OvkLGRHIs9/?= =?us-ascii?Q?XqxewA05+qpnGqMnbynIBJu59kwwsnCrNW0CTVwUfZiuJ6KReEnsKPv6qSRR?= =?us-ascii?Q?UYKQdBzfuoMsaVhvDWrUN4h8C9DRVJDj2jF8gHtJS+d81mERRtnKw0zQgdhl?= =?us-ascii?Q?c0DufHV+mSsg2ELcsDqDwdOuwsq0YxK52QSMPRJOjGHprFGdByMcIbaB1UTV?= =?us-ascii?Q?/YYxTXojiBqrGfaeIRHPTH8VQe3BWrE+zqvFrJu7ccSm1UvOCDfQvsoyFatZ?= =?us-ascii?Q?dfcXRkgahyZYzPKv6u1/qGD6wALxzp5DaMy/4fHJWyzUkTaZW1A7iL6xJWYW?= =?us-ascii?Q?R6TbJaC4hhpflH/jM7+pnkQtPlx0MTdqczGipqD6pQg2FzCTWVugbuFMeRch?= =?us-ascii?Q?zXxm3sZt7vQmCc1oyXs/YQrWpo2qL8QqgNYtnVBxJ3AUYCgo8URYWJeDH6ap?= =?us-ascii?Q?oW8Ggu745t4SfyawWJSXn4bdnFqORkufPBwpb+OpYN99c3Zn8HHGn8G7YvAe?= =?us-ascii?Q?UgxRc16vbrz4LNHCPfwjxPNhjJflHjhVtaSyUabh7KmrItSrcNdZwK9uCkuB?= =?us-ascii?Q?wVDnC1PTxudiexPOPlTf5knOKbIaP3vALgV8jCfwMqAxpMBD+nt+EliB/nE0?= =?us-ascii?Q?ocErAC0G6QISY1sZkMMj1HOU6TwjJ8JHKc9B7pfOZmWf/kDVB23UC+7K3ddU?= =?us-ascii?Q?7VTZxCeqdtaArfN2GgUrY91Uhpa6HgQC0il7AScwd9Ld8cKM8RXW2FGOxgNC?= =?us-ascii?Q?i0UO1cHfrVyo4XovQX/HJvtUKBJ4EZkg6TYfWT9ZI1CD5a320VwpFTir1s/T?= =?us-ascii?Q?SFCPvS+O9Q39qHSoCiYqg0P8yv87B7xi6YqsSYGfxwo7bdgeadqb/Tn7hKQ7?= =?us-ascii?Q?EGGla9xN6Y+zQK9FxOAmZ7OIhUJOeYJ2afH9hTurpEnhMQUqYdX3hCjBVUZD?= =?us-ascii?Q?t2Dt5SrTbFEChgP/hl+o0zhjCUq2M3iwTuExY8DYEEMpd2i5ZKWLYdXgpQI/?= =?us-ascii?Q?NA+yc40S5cbocQ9x0adNtc4zvyYxboo3lUevOI0IykT096ZRINPehNdpRcLu?= =?us-ascii?Q?gtVa7aycXl+koXUl1wYD7wzKf/RTXQr0C3efcv2bt/BL7i+ptbioc41Qg0Fp?= =?us-ascii?Q?GBwaDft1894xjYdlBq7hprptWJfDV+cjD4Lvffgz6wzD9fF1a0KcPewxdM39?= =?us-ascii?Q?+bM5oA=3D=3D?= X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-Network-Message-Id: a3907aef-44f2-4dc6-13fc-08de07eafed3 X-MS-Exchange-CrossTenant-AuthSource: AM8PR04MB7779.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Oct 2025 10:51:41.4516 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 7jsg+HOLLlBoDBoJkrKeg6LmJbcD5b2PN46XmwAKBgw6hgePz1GlvHyjrf5LRZYfi94xm4H+CffuUvfLz3VRNQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PAXPR04MB9708 On Fri, Oct 10, 2025 at 12:31:37PM +0300, Wei Fang wrote: > > After applying the workaround for err050089, the LS1028A platform > > experiences RCU stalls on RT kernel. This issue is caused by the > > recursive acquisition of the read lock enetc_mdio_lock. Here list some > > of the call stacks identified under the enetc_poll path that may lead to > > a deadlock: > > > > enetc_poll > > -> enetc_lock_mdio > > -> enetc_clean_rx_ring OR napi_complete_done > > -> napi_gro_receive > > -> enetc_start_xmit > > -> enetc_lock_mdio > > -> enetc_map_tx_buffs > > -> enetc_unlock_mdio > > -> enetc_unlock_mdio > > > > After enetc_poll acquires the read lock, a higher-priority writer attempts > > to acquire the lock, causing preemption. The writer detects that a > > read lock is already held and is scheduled out. However, readers under > > enetc_poll cannot acquire the read lock again because a writer is already > > waiting, leading to a thread hang. > > > > Currently, the deadlock is avoided by adjusting enetc_lock_mdio to prevent > > recursive lock acquisition. > > > > Fixes: 6d36ecdbc441 ("net: enetc: take the MDIO lock only once per NAPI poll > > cycle") > > Signed-off-by: Jianpeng Chang > > Acked-by: Wei Fang > > Hi Vladimir, > > Do you have any comments? This patch will cause the regression of performance > degradation, but the RCU stalls are more severe. > I'm fine with the change in principle. It's my fault because I didn't understand how rwlock writer starvation prevention is implemented, I thought there would be no problem with reentrant readers. But I wonder if xdp_do_flush() shouldn't also be outside the enetc_lock_mdio() section. Flushing XDP buffs with XDP_REDIRECT action might lead to enetc_xdp_xmit() being called, which also takes the lock...