linux-kernel - [PATCH] mtd: core: clear out unregistered devices a bit more

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Message-Id: <20211015185049.3318-1-zev@bewilderbeest.net>
Date:   Fri, 15 Oct 2021 11:50:48 -0700
From:   Zev Weiss <zev@...ilderbeest.net>
To:     linux-mtd@...ts.infradead.org
Cc:     Zev Weiss <zev@...ilderbeest.net>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Michael Walle <michael@...le.cc>,
        Zhen Lei <thunder.leizhen@...wei.com>,
        Lee Jones <lee.jones@...aro.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Tian Tao <tiantao6@...ilicon.com>, Petr Malat <oss@...at.biz>,
        Jon Hunter <jonathanh@...dia.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] mtd: core: clear out unregistered devices a bit more

This allows an MTD device that has been unregistered to be easily
re-registered later without triggering spurious "already registered"
warnings in mtd_device_parse_register() and add_mtd_device().

Signed-off-by: Zev Weiss <zev@...ilderbeest.net>
---
 drivers/mtd/mtdcore.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 153229198947..0a0fca737d43 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -747,6 +747,9 @@ int del_mtd_device(struct mtd_info *mtd)
 
 		device_unregister(&mtd->dev);
 
+		/* Clear dev so mtd can be safely re-registered later if desired */
+		memset(&mtd->dev, 0, sizeof(mtd->dev));
+
 		idr_remove(&mtd_idr, mtd->index);
 		of_node_put(mtd_get_of_node(mtd));
 
@@ -1018,8 +1021,10 @@ int mtd_device_unregister(struct mtd_info *master)
 {
 	int err;
 
-	if (master->_reboot)
+	if (master->_reboot) {
 		unregister_reboot_notifier(&master->reboot_notifier);
+		memset(&master->reboot_notifier, 0, sizeof(master->reboot_notifier));
+	}
 
 	if (master->otp_user_nvmem)
 		nvmem_unregister(master->otp_user_nvmem);
-- 
2.33.0