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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?UXklcvId58Djh0b69IBZwgbxB1hC7Aa8AUHqvUdOLSc/BDqlXHehdbWcckIt?= =?us-ascii?Q?g77fTIRop4m8o3+kDkiiow4g4ydvnmMYPQ+nvDee1KGNg6x6Fdqe1EV3DiNs?= =?us-ascii?Q?SWXLhtT/vX85yD7Lx65TugYrHnzkoLSIGSYokyNKDhg5H4/eVzQYs+sPtgXh?= =?us-ascii?Q?E68Viold+Kzb7EKS4l3HaDtGIKUvtf5ZO+C7aYAMjrKhPTE9ul9zqxExsPZE?= =?us-ascii?Q?NIBUosWRr1zeY5TIoLtSb7CEabzWRwFksoCgcODbviBkn3v9pMtZzvPSQ5ki?= =?us-ascii?Q?zU1sAqh2Mab+d5g5oiHBODfM9K8J78aKvaJG0TRMWNuWZVla8gDoRCIZmtgH?= =?us-ascii?Q?26Ai1CfqcuGxuN7aRMO0JZfXnJ2LCqx4Uio8Eb7sMpVskY2CJJ4Xk/POd053?= =?us-ascii?Q?xczJJ7Ge+3Pp1RW3a6EcgpfMlei9cAvzn7uThAsLwALL8b/WEfDZNVFwX3kT?= =?us-ascii?Q?+zRiSuc/JVcbJnMJDCn3kMEaYl/Q0zqo/4ayHOq6l+BYswfUEdeWRpQL56+y?= =?us-ascii?Q?k5bRCCjkLRQ1hC9pUYVeFjotkQ3MJ1NBC57ptb5HUNvb9VNVg0k8O0rWEeXJ?= =?us-ascii?Q?owTIF4Av4woQS9pno/lmt++Ca8VkGI2qo83AjvkaqK2D28mGtVhIH4eyvzPt?= =?us-ascii?Q?ffkLoBlYv5fgC1/g1Rz1vrHNYxMDwOxNIUBPYLw7yQUR8+rxBWMrB9xDGZQD?= =?us-ascii?Q?5rCuNDOta7DS5OMT03vStKfDGIjL4YB0nCil81/aAfzKMjV8c1U0BStg3ND9?= =?us-ascii?Q?rU1Va7Ji9zuTrFcAe3jjrkjDqfYwdjt1AqZ3vFJd6lWt8CqA5KNsXnJuD3h7?= =?us-ascii?Q?WRWUNFgNgKpbsS7nPpOhkeYm9tJlddp6WhOm6yXynADZNwOltnlBEVw4VjJq?= =?us-ascii?Q?Si2Idr5nsqaVzvkMB2HsRaN1gF8BgixEaRMVIB3aKdVUaZwHztxLFYAe7dxO?= =?us-ascii?Q?1MyRfrOJrcri3IdI+ZlZm1lhdkInHpdALVhv6pMo1JoUcgEuVGYTpMdMxw4/?= =?us-ascii?Q?yEVmMie6KI85YyWcWLoss+9jiPZqzlZHDwhFqh9BSqcYK2C7cf0vWMd6Bg9l?= =?us-ascii?Q?qsWAbTFr6wSc/qG3LICyxkbMnW3rnhcEB7K8XEVD6wGiBkwaclrsSajbMwpG?= =?us-ascii?Q?qkCfWHuwkDnydUAjg7lFiR7nFaJ/UvcY7vh+ix1cU6gMNCb7HpnC7sPCDYav?= =?us-ascii?Q?doVGNIF2u57u4lzeWTMVuTkFuB1FeDGzYLD7+MRjlCzRBFC+ZlxQGJDOJnx/?= =?us-ascii?Q?sa33kxjbBrlq0a7H+WV1CKgJ5JgH10edY03GzV1tZKO6QuzF3D35ue8hpf+y?= =?us-ascii?Q?y55fYfzowgp9T5GG/zmd1vZ3bqzpZS+hrYq5Jdc3H65/FEdSkXFaLQYCOHFE?= =?us-ascii?Q?+fNGTDeZoJF48MyCiALyZCtjuMpaw2f0DOxPJHAZEyvHXw6U0KCbBxfMIsBQ?= =?us-ascii?Q?FTzYWpozQvN30EGW93KVsG/A5YZsMZb6k/t1E39vZteQl3vB4aJtfYE/wy7Z?= =?us-ascii?Q?YSC1pbvwOWUZWYOUyioSWsHxlpzjrvjhUzxU5Xs54rTHyR75npiQDXhFq6X5?= =?us-ascii?Q?8kdTyWqvGf9zV+WF9e3csOHabRumFgcjEm6RwNXpWDBuFkErd5VaqpRUpUl2?= =?us-ascii?Q?1lBuRsYIU3aUCLcgISMIcxWqv8JnHU32P/5pnQZc8e/vTDTfmBJvoigluNSl?= =?us-ascii?Q?DPgirMLpUvaw0DldWiwZaW9fos3egsO3/ph9F0D2Vxs3FPT0?= X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-Network-Message-Id: bde71135-b117-4dfa-ffa0-08de7617cf0c X-MS-Exchange-CrossTenant-AuthSource: DU0PR04MB9372.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Feb 2026 15:49:36.4083 (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: Q0xFuCM8bASCdMnkzNWP77MZ/b5vYW4d6tSayKtm2q0vWNROvWh8sUgXrL5MiZy7H2RTvfCjlPDZJFQwhajJjA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MRWPR04MB12048 On Fri, Feb 27, 2026 at 05:49:47PM +0900, Koichiro Den wrote: > The NTB .peer_db_set() callback may be invoked from atomic context. > pci-epf-vntb currently calls pci_epc_raise_irq() directly, but > pci_epc_raise_irq() may sleep (it takes epc->lock). > > Avoid sleeping in atomic context by coalescing doorbell bits into an > atomic64 pending mask and raising MSIs from a work item. Limit the > amount of work per run to avoid monopolizing the workqueue under a > doorbell storm. > > Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP") > Signed-off-by: Koichiro Den > --- > Changes since v1: > - No functional changes. > - Updated comment in vntb_epf_peer_db_work(). > > drivers/pci/endpoint/functions/pci-epf-vntb.c | 106 +++++++++++++----- > 1 file changed, 78 insertions(+), 28 deletions(-) > > diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c > index 83372aba5106..e2c0b6dba793 100644 > --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c > +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c > @@ -69,6 +69,9 @@ static struct workqueue_struct *kpcintb_workqueue; > #define MAX_DB_COUNT 32 > #define MAX_MW 4 > > +/* Limit per-work execution to avoid monopolizing kworker on doorbell storms. */ > +#define VNTB_PEER_DB_WORK_BUDGET 5 > + > enum epf_ntb_bar { > BAR_CONFIG, > BAR_DB, > @@ -129,6 +132,8 @@ struct epf_ntb { > u32 spad_count; > u64 mws_size[MAX_MW]; > atomic64_t db; > + atomic64_t peer_db_pending; > + struct work_struct peer_db_work; > u32 vbus_number; > u16 vntb_pid; > u16 vntb_vid; > @@ -933,6 +938,8 @@ static int epf_ntb_epc_init(struct epf_ntb *ntb) > INIT_DELAYED_WORK(&ntb->cmd_handler, epf_ntb_cmd_handler); > queue_work(kpcintb_workqueue, &ntb->cmd_handler.work); > > + enable_work(&ntb->peer_db_work); > + > return 0; > > err_write_header: > @@ -955,6 +962,7 @@ static int epf_ntb_epc_init(struct epf_ntb *ntb) > */ > static void epf_ntb_epc_cleanup(struct epf_ntb *ntb) > { > + disable_work_sync(&ntb->peer_db_work); > epf_ntb_mw_bar_clear(ntb, ntb->num_mws); > epf_ntb_db_bar_clear(ntb); > epf_ntb_config_sspad_bar_clear(ntb); > @@ -1369,41 +1377,79 @@ static int vntb_epf_peer_spad_write(struct ntb_dev *ndev, int pidx, int idx, u32 > return 0; > } > > +static void vntb_epf_peer_db_work(struct work_struct *work) > +{ > + struct epf_ntb *ntb = container_of(work, struct epf_ntb, peer_db_work); > + struct pci_epf *epf = ntb->epf; > + unsigned int budget = VNTB_PEER_DB_WORK_BUDGET; > + u8 func_no, vfunc_no; > + u32 interrupt_num; > + u64 db_bits; > + int ret; > + > + if (!epf || !epf->epc) > + return; > + > + func_no = epf->func_no; > + vfunc_no = epf->vfunc_no; > + > + /* > + * Drain doorbells from peer_db_pending in snapshots (atomic64_xchg()). > + * Limit the number of snapshots handled per run so we don't monopolize > + * the workqueue under a doorbell storm. > + */ > + while (budget--) { > + db_bits = atomic64_xchg(&ntb->peer_db_pending, 0); > + if (!db_bits) > + return; > + > + while (db_bits) { > + /* > + * pci_epc_raise_irq() for MSI expects a 1-based > + * interrupt number. ffs() returns a 1-based index (bit > + * 0 -> 1). We historically add +2 to compute > + * interrupt_num. > + * > + * Legacy mapping (kept for compatibility): > + * > + * MSI #1 : link event (reserved) > + * MSI #2 : unused (historical offset) > + * MSI #3 : doorbell bit 0 (DB#0) > + * MSI #4 : doorbell bit 1 (DB#1) > + * ... > + * > + * Do not change this mapping to avoid breaking > + * interoperability with older peers. > + */ > + interrupt_num = ffs(db_bits) + 2; > + db_bits &= db_bits - 1; > + > + ret = pci_epc_raise_irq(epf->epc, func_no, vfunc_no, > + PCI_IRQ_MSI, interrupt_num); > + if (ret) > + dev_err(&ntb->ntb.dev, > + "Failed to raise IRQ for interrupt_num %u: %d\n", > + interrupt_num, ret); > + } > + } > + > + if (atomic64_read(&ntb->peer_db_pending)) > + queue_work(kpcintb_workqueue, &ntb->peer_db_work); > +} > + > static int vntb_epf_peer_db_set(struct ntb_dev *ndev, u64 db_bits) > { > - u32 interrupt_num = ffs(db_bits) + 1; > struct epf_ntb *ntb = ntb_ndev(ndev); > - u8 func_no, vfunc_no; > - int ret; > - > - func_no = ntb->epf->func_no; > - vfunc_no = ntb->epf->vfunc_no; > > /* > - * pci_epc_raise_irq() for MSI expects a 1-based interrupt number. > - * ffs() returns a 1-based index (bit 0 -> 1). interrupt_num has already > - * been computed as ffs(db_bits) + 1 above. Adding one more +1 when > - * calling pci_epc_raise_irq() therefore results in: > - * > - * doorbell bit 0 -> MSI #3 > - * > - * Legacy mapping (kept for compatibility): > - * > - * MSI #1 : link event (reserved) > - * MSI #2 : unused (historical offset) > - * MSI #3 : doorbell bit 0 (DB#0) > - * MSI #4 : doorbell bit 1 (DB#1) > - * ... > - * > - * Do not change this mapping to avoid breaking interoperability with > - * older peers. > + * .peer_db_set() may be called from atomic context. pci_epc_raise_irq() > + * can sleep (it takes epc->lock), so defer MSI raising to process > + * context. Doorbell requests are coalesced in peer_db_pending. > */ > - ret = pci_epc_raise_irq(ntb->epf->epc, func_no, vfunc_no, > - PCI_IRQ_MSI, interrupt_num + 1); > - if (ret) > - dev_err(&ntb->ntb.dev, "Failed to raise IRQ\n"); > + atomic64_or(db_bits, &ntb->peer_db_pending); > + queue_work(kpcintb_workqueue, &ntb->peer_db_work); > > - return ret; > + return 0; > } > > static u64 vntb_epf_db_read(struct ntb_dev *ndev) > @@ -1645,6 +1691,10 @@ static int epf_ntb_probe(struct pci_epf *epf, > ntb->epf = epf; > ntb->vbus_number = 0xff; > > + INIT_WORK(&ntb->peer_db_work, vntb_epf_peer_db_work); > + disable_work(&ntb->peer_db_work); > + atomic64_set(&ntb->peer_db_pending, 0); > + Does it need call disable_work_sync() in unbind or remove() function? Frank > /* Initially, no bar is assigned */ > for (i = 0; i < VNTB_BAR_NUM; i++) > ntb->epf_ntb_bar[i] = NO_BAR; > -- > 2.51.0 >