linux-kernel - [PATCH] mtd: core: don't remove debugfs directory if device is in use

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Date:   Thu, 14 Oct 2021 13:39:52 -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>,
        Tian Tao <tiantao6@...ilicon.com>,
        Jon Hunter <jonathanh@...dia.com>, Petr Malat <oss@...at.biz>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Mario Rugiero <mrugiero@...il.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] mtd: core: don't remove debugfs directory if device is in use

Previously, if del_mtd_device() failed with -EBUSY due to a non-zero
usecount, a subsequent call to attempt the deletion again would try to
remove a debugfs directory that had already been removed and panic.
With this change the second call can instead proceed safely.

Fixes: e8e3edb95ce6 ("mtd: create per-device and module-scope debugfs entries")
Signed-off-by: Zev Weiss <zev@...ilderbeest.net>
---
 drivers/mtd/mtdcore.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index e22266f63ae9..0a0fca737d43 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -724,8 +724,6 @@ int del_mtd_device(struct mtd_info *mtd)
 
 	mutex_lock(&mtd_table_mutex);
 
-	debugfs_remove_recursive(mtd->dbg.dfs_dir);
-
 	if (idr_find(&mtd_idr, mtd->index) != mtd) {
 		ret = -ENODEV;
 		goto out_error;
@@ -741,6 +739,8 @@ int del_mtd_device(struct mtd_info *mtd)
 		       mtd->index, mtd->name, mtd->usecount);
 		ret = -EBUSY;
 	} else {
+		debugfs_remove_recursive(mtd->dbg.dfs_dir);
+
 		/* Try to remove the NVMEM provider */
 		if (mtd->nvmem)
 			nvmem_unregister(mtd->nvmem);
-- 
2.33.0