From a623128bc2a1c257cbad97d0582f355fbe7be927 Mon Sep 17 00:00:00 2001 From: Alison Schofield Date: Mon, 13 Jul 2026 19:04:35 -0700 Subject: [PATCH] cxl/port: Restart port enumeration when a sibling adds the dport first Endpoint probes can race while enumerating a shared switch. If a sibling probe adds the dport first, the losing probe finds the dport already present, gets -EBUSY, and fails to enumerate the endpoint. Treat this race the same as the existing port-created case by restarting the port walk, allowing it to find the existing dport and continue enumeration. This race was discovered while testing a cxl_test mixed-granularity topology, where twelve endpoints behind shared switches are probed in parallel during module load. Fixes: 4f06d81e7c6a ("cxl: Defer dport allocation for switch ports") Signed-off-by: Alison Schofield Tested-by: Li Ming Reviewed-by: Li Ming Link: https://patch.msgid.link/20260714020438.1822669-1-alison.schofield@intel.com Signed-off-by: Dave Jiang --- drivers/cxl/core/port.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index 1215ee4f4035..65f2d2f1eb00 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -1749,8 +1749,8 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd, parent_dport, uport_dev, dport_dev); if (IS_ERR(dport)) { - /* Port already exists, restart iteration */ - if (PTR_ERR(dport) == -EAGAIN) + /* Port or dport already exists, restart iteration */ + if (PTR_ERR(dport) == -EAGAIN || PTR_ERR(dport) == -EBUSY) return 0; return PTR_ERR(dport); }