5.15-stable review patch. If anyone has any objections, please let me know.
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From: Daniel Wagner wagi@kernel.org
[ Upstream commit f2537be4f8421f6495edfa0bc284d722f253841d ]
When forcefully shutting down a port via the configfs interface, nvmet_port_subsys_drop_link() first calls nvmet_port_del_ctrls() and then nvmet_disable_port(). Both functions will eventually schedule all remaining associations for deletion.
The current implementation checks whether an association is about to be removed, but only after the work item has already been scheduled. As a result, it is possible for the first scheduled work item to free all resources, and then for the same work item to be scheduled again for deletion.
Because the association list is an RCU list, it is not possible to take a lock and remove the list entry directly, so it cannot be looked up again. Instead, a flag (terminating) must be used to determine whether the association is already in the process of being deleted.
Reported-by: Shinichiro Kawasaki shinichiro.kawasaki@wdc.com Closes: https://lore.kernel.org/all/rsdinhafrtlguauhesmrrzkybpnvwantwmyfq2ih5areggha... Reviewed-by: Hannes Reinecke hare@suse.de Signed-off-by: Daniel Wagner wagi@kernel.org Signed-off-by: Keith Busch kbusch@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/nvme/target/fc.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c index 4c4b528b89ebe..80e0dc60a9205 100644 --- a/drivers/nvme/target/fc.c +++ b/drivers/nvme/target/fc.c @@ -1090,6 +1090,14 @@ nvmet_fc_delete_assoc_work(struct work_struct *work) static void nvmet_fc_schedule_delete_assoc(struct nvmet_fc_tgt_assoc *assoc) { + int terminating; + + terminating = atomic_xchg(&assoc->terminating, 1); + + /* if already terminating, do nothing */ + if (terminating) + return; + nvmet_fc_tgtport_get(assoc->tgtport); if (!queue_work(nvmet_wq, &assoc->del_work)) nvmet_fc_tgtport_put(assoc->tgtport); @@ -1209,13 +1217,7 @@ nvmet_fc_delete_target_assoc(struct nvmet_fc_tgt_assoc *assoc) { struct nvmet_fc_tgtport *tgtport = assoc->tgtport; unsigned long flags; - int i, terminating; - - terminating = atomic_xchg(&assoc->terminating, 1); - - /* if already terminating, do nothing */ - if (terminating) - return; + int i;
spin_lock_irqsave(&tgtport->lock, flags); list_del_rcu(&assoc->a_list);