From: Pavel Begunkov <asml.silence@xxxxxxxxx>
When the taks that submitted a request is dying, a task work for that
request might get run by a kernel thread or even worse by a half
dismantled task. We can't just cancel the task work without running the
callback as the cmd might need to do some clean up, so pass a flag
instead. If set, it's not safe to access any task resources and the
callback is expected to cancel the cmd ASAP.
Changed to
if (req->task != current)
based on discussion with Jens, needs to be double verified if really
needed.
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Signed-off-by: Bernd Schubert <bschubert@xxxxxxx>
---
include/linux/io_uring_types.h | 1 +
io_uring/uring_cmd.c | 6 +++++-
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 7abdc09271245ff7de3fb9a905ca78b7561e37eb..869a81c63e4970576155043fce7fe656293d7f58 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -37,6 +37,7 @@ enum io_uring_cmd_flags {
/* set when uring wants to cancel a previously issued command */
IO_URING_F_CANCEL = (1 << 11),
IO_URING_F_COMPAT = (1 << 12),
+ IO_URING_F_TASK_DEAD = (1 << 13),
};
struct io_wq_work_node {
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 21ac5fb2d5f087e1174d5c94815d580972db6e3f..405a39fdd91c9abf741c2b3b6bde2f4d850312ae 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -119,9 +119,13 @@ EXPORT_SYMBOL_GPL(io_uring_cmd_mark_cancelable);
static void io_uring_cmd_work(struct io_kiocb *req, struct io_tw_state *ts)
{
struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd);
+ unsigned int flags = IO_URING_F_COMPLETE_DEFER;
+
+ if (req->task->flags & PF_EXITING)
+ flags |= IO_URING_F_TASK_DEAD;
/* task_work executor checks the deffered list completion */
- ioucmd->task_work_cb(ioucmd, IO_URING_F_COMPLETE_DEFER);
+ ioucmd->task_work_cb(ioucmd, flags);
}
void __io_uring_cmd_do_in_task(struct io_uring_cmd *ioucmd,
--
2.43.0
