Patch "mtd: spi-nor: fix memory leak when using debugfs_lookup()" has been added to the 6.2-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    mtd: spi-nor: fix memory leak when using debugfs_lookup()

to the 6.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mtd-spi-nor-fix-memory-leak-when-using-debugfs_looku.patch
and it can be found in the queue-6.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 973a6e1ae1b3bfb951696e25cc05c60c0b36f2ff
Author: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Date:   Wed Feb 8 17:02:30 2023 +0100

    mtd: spi-nor: fix memory leak when using debugfs_lookup()
    
    [ Upstream commit ec738ca127d07ecac6afae36e2880341ec89150e ]
    
    When calling debugfs_lookup() the result must have dput() called on it,
    otherwise the memory will leak over time.  To solve this, remove the
    lookup and create the directory on the first device found, and then
    remove it when the module is unloaded.
    
    Cc: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
    Cc: Pratyush Yadav <pratyush@xxxxxxxxxx>
    Cc: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
    Cc: Richard Weinberger <richard@xxxxxx>
    Cc: Vignesh Raghavendra <vigneshr@xxxxxx>
    Cc: linux-mtd@xxxxxxxxxxxxxxxxxxx
    Reviewed-by: Michael Walle <michael@xxxxxxxx>
    Link: https://lore.kernel.org/r/20230208160230.2179905-1-gregkh@xxxxxxxxxxxxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 2ef2660f58180..4244c6fd98111 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -3344,7 +3344,19 @@ static struct spi_mem_driver spi_nor_driver = {
 	.remove = spi_nor_remove,
 	.shutdown = spi_nor_shutdown,
 };
-module_spi_mem_driver(spi_nor_driver);
+
+static int __init spi_nor_module_init(void)
+{
+	return spi_mem_driver_register(&spi_nor_driver);
+}
+module_init(spi_nor_module_init);
+
+static void __exit spi_nor_module_exit(void)
+{
+	spi_mem_driver_unregister(&spi_nor_driver);
+	spi_nor_debugfs_shutdown();
+}
+module_exit(spi_nor_module_exit);
 
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Huang Shijie <shijie8@xxxxxxxxx>");
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 958cd143c9346..f4246c52a1def 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -714,8 +714,10 @@ static inline struct spi_nor *mtd_to_spi_nor(struct mtd_info *mtd)
 
 #ifdef CONFIG_DEBUG_FS
 void spi_nor_debugfs_register(struct spi_nor *nor);
+void spi_nor_debugfs_shutdown(void);
 #else
 static inline void spi_nor_debugfs_register(struct spi_nor *nor) {}
+static inline void spi_nor_debugfs_shutdown(void) {}
 #endif
 
 #endif /* __LINUX_MTD_SPI_NOR_INTERNAL_H */
diff --git a/drivers/mtd/spi-nor/debugfs.c b/drivers/mtd/spi-nor/debugfs.c
index ff895f6758ea1..558ffecf8ae6d 100644
--- a/drivers/mtd/spi-nor/debugfs.c
+++ b/drivers/mtd/spi-nor/debugfs.c
@@ -226,13 +226,13 @@ static void spi_nor_debugfs_unregister(void *data)
 	nor->debugfs_root = NULL;
 }
 
+static struct dentry *rootdir;
+
 void spi_nor_debugfs_register(struct spi_nor *nor)
 {
-	struct dentry *rootdir, *d;
+	struct dentry *d;
 	int ret;
 
-	/* Create rootdir once. Will never be deleted again. */
-	rootdir = debugfs_lookup(SPI_NOR_DEBUGFS_ROOT, NULL);
 	if (!rootdir)
 		rootdir = debugfs_create_dir(SPI_NOR_DEBUGFS_ROOT, NULL);
 
@@ -247,3 +247,8 @@ void spi_nor_debugfs_register(struct spi_nor *nor)
 	debugfs_create_file("capabilities", 0444, d, nor,
 			    &spi_nor_capabilities_fops);
 }
+
+void spi_nor_debugfs_shutdown(void)
+{
+	debugfs_remove(rootdir);
+}