From a11f0b8a204296fe7db9eaec53441012222cb004 Mon Sep 17 00:00:00 2001 From: "Nikhil P. Rao" Date: Tue, 14 Jul 2026 20:14:56 +0000 Subject: [PATCH] pds_core: yield the CPU while waiting for the adminq to drain pdsc_adminq_wait_and_dec_once_unused() busy-waits for adminq_refcnt to drop to one: while (!refcount_dec_if_one(&pdsc->adminq_refcnt)) cpu_relax(); The refcount is held by pdsc_adminq_post() for the duration of an in-flight command, which can wait up to devcmd_timeout seconds (PDS_CORE_DEVCMD_TIMEOUT is 5) for the hardware to complete. cpu_relax() is not a reschedule point, so on a non-preemptible kernel this loop can spin on the CPU for several seconds, starving other tasks on that core. Add cond_resched() to the loop so the waiter yields to other runnable tasks while it polls, keeping cpu_relax() as the busy-wait hint between checks. Fixes: 7e82a8745b95 ("pds_core: Prevent race issues involving the adminq") Reported-by: sashiko-bot Closes: https://sashiko.dev/#/patchset/20260629200358.2626129-1-nikhil.rao%40amd.com?part=2 Signed-off-by: Nikhil P. Rao Reviewed-by: Eric Joyner Reviewed-by: Pavan Chebbi Link: https://patch.msgid.link/20260714201456.1776153-1-nikhil.rao@amd.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/amd/pds_core/core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/ethernet/amd/pds_core/core.c b/drivers/net/ethernet/amd/pds_core/core.c index e39b2c9beb20..04ec2569c61c 100644 --- a/drivers/net/ethernet/amd/pds_core/core.c +++ b/drivers/net/ethernet/amd/pds_core/core.c @@ -539,6 +539,7 @@ static void pdsc_adminq_wait_and_dec_once_unused(struct pdsc *pdsc) dev_dbg_ratelimited(pdsc->dev, "%s: adminq in use\n", __func__); cpu_relax(); + cond_resched(); } } -- 2.47.3