[PATCH v5 2/4] mtd: mtdconcat: don't use mtd_{suspend,resume}()

From: Sean Nyekjaer
Date: Tue Nov 02 2021 - 07:02:29 EST


From: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>

The MTD suspend logic will soon be adjusted to automatically wait for
device wake-up before issuing IOs. In order to do that a new read-write
lock will be added and taken in write-mode in the
mtd_{suspend,resume}() path. Since mtdconcat.c itself is an MTD device,
calling mtd_suspend/resume() on subdevices from the mtdconcat
->_{suspend,resume}() hook will lead to a nested lock, which lockdep
will complain about if we don't add a proper annotation. Let's keep
things simple and replace those mtd_{suspend,resume}(subdev) calls by
subdev->_{suspend,resume}() ones to avoid this situation.

Tested-by: Sean Nyekjaer <sean@xxxxxxxxxx>
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
Signed-off-by: Sean Nyekjaer <sean@xxxxxxxxxx>
---
drivers/mtd/mtdconcat.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c
index f685a581df48..f4a4274489b4 100644
--- a/drivers/mtd/mtdconcat.c
+++ b/drivers/mtd/mtdconcat.c
@@ -566,9 +566,15 @@ static int concat_suspend(struct mtd_info *mtd)

for (i = 0; i < concat->num_subdev; i++) {
struct mtd_info *subdev = concat->subdev[i];
- if ((rc = mtd_suspend(subdev)) < 0)
+ /*
+ * Call the MTD hook directly to avoid a nested lock
+ * on ->suspend_lock.
+ */
+ rc = subdev->_suspend ? subdev->_suspend(subdev) : 0;
+ if (rc < 0)
return rc;
}
+
return rc;
}

@@ -579,7 +585,12 @@ static void concat_resume(struct mtd_info *mtd)

for (i = 0; i < concat->num_subdev; i++) {
struct mtd_info *subdev = concat->subdev[i];
- mtd_resume(subdev);
+ /*
+ * Call the MTD hook directly to avoid a nested lock
+ * on ->resume_lock.
+ */
+ if (subdev->_resume)
+ subdev->_resume(subdev);
}
}

--
2.33.0