From 5b130aadc36b6a935b90937dcd67b8ed4ba57831 Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Mon, 8 Jun 2026 08:43:06 +0300 Subject: [PATCH] i3c: master: Serialize i3c_set_hotjoin() with the maintenance lock i3c_set_hotjoin() dispatches the controller's enable_hotjoin() or disable_hotjoin() op and updates master->hotjoin under i3c_bus_normaluse_lock(). That lock is a read-side acquisition of bus->lock (down_read()), so it does not exclude concurrent callers. The hotjoin sysfs attribute can be opened multiple times, and writes through different opens are not serialized. Two concurrent writers to "hotjoin" can therefore race in i3c_set_hotjoin(), with the controller op and the master->hotjoin store from one call interleaving with the other. The hardware enable/disable state and the value reported by hotjoin_show() can end up out of sync. Take i3c_bus_maintenance_lock() instead. Toggling Hot Join enable changes bus state and is conceptually a maintenance operation, so the write-side acquisition of bus->lock is the appropriate lock and serializes concurrent callers against each other and against other maintenance operations. Fixes: 317bacf960a48 ("i3c: master: add enable(disable) hot join in sys entry") Signed-off-by: Adrian Hunter Reviewed-by: Frank Li Link: https://patch.msgid.link/20260608054312.10604-3-adrian.hunter@intel.com Signed-off-by: Alexandre Belloni --- drivers/i3c/master.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index 5b64e40dae67..a3a790a14286 100644 --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -649,7 +649,7 @@ static int i3c_set_hotjoin(struct i3c_master_controller *master, bool enable) return ret; } - i3c_bus_normaluse_lock(&master->bus); + i3c_bus_maintenance_lock(&master->bus); if (enable) ret = master->ops->enable_hotjoin(master); @@ -659,7 +659,7 @@ static int i3c_set_hotjoin(struct i3c_master_controller *master, bool enable) if (!ret) master->hotjoin = enable; - i3c_bus_normaluse_unlock(&master->bus); + i3c_bus_maintenance_unlock(&master->bus); if ((enable && ret) || (!enable && !ret) || master->rpm_ibi_allowed) i3c_master_rpm_put(master);