Commit 1ad55288 authored by Alexander Sverdlin's avatar Alexander Sverdlin Committed by Miquel Raynal
Browse files

mtd: char: Get rid of Big MTD Lock 



Get rid of central chrdev MTD lock, which prevents simultaneous operations
on completely independent physical MTD chips. Replace it with newly
introduced per-master mutex.

Signed-off-by: default avatarAlexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210217211845.43364-2-alexander.sverdlin@nokia.com
parent ecd400ce

drivers/mtd/mtdchar.c

+8 −6
Original line number Diff line number Diff line
@@ -27,8 +27,6 @@ 


#include "mtdcore.h"



static DEFINE_MUTEX(mtd_mutex);



/*

 * Data structure to hold the pointer to the mtd device as well

 * as mode information of various use cases.
@@ -1020,11 +1018,14 @@ static int mtdchar_ioctl(struct file *file, u_int cmd, u_long arg) 


static long mtdchar_unlocked_ioctl(struct file *file, u_int cmd, u_long arg)

{

	struct mtd_file_info *mfi = file->private_data;

	struct mtd_info *mtd = mfi->mtd;

	struct mtd_info *master = mtd_get_master(mtd);

	int ret;



	mutex_lock(&mtd_mutex);

	mutex_lock(&master->master.chrdev_lock);

	ret = mtdchar_ioctl(file, cmd, arg);

	mutex_unlock(&mtd_mutex);

	mutex_unlock(&master->master.chrdev_lock);



	return ret;

}
@@ -1045,10 +1046,11 @@ static long mtdchar_compat_ioctl(struct file *file, unsigned int cmd, 
{

	struct mtd_file_info *mfi = file->private_data;

	struct mtd_info *mtd = mfi->mtd;

	struct mtd_info *master = mtd_get_master(mtd);

	void __user *argp = compat_ptr(arg);

	int ret = 0;



	mutex_lock(&mtd_mutex);

	mutex_lock(&master->master.chrdev_lock);



	switch (cmd) {

	case MEMWRITEOOB32:
@@ -1111,7 +1113,7 @@ static long mtdchar_compat_ioctl(struct file *file, unsigned int cmd, 
		ret = mtdchar_ioctl(file, cmd, (unsigned long)argp);

	}



	mutex_unlock(&mtd_mutex);

	mutex_unlock(&master->master.chrdev_lock);



	return ret;

}

drivers/mtd/mtdcore.c

+1 −0
Original line number Diff line number Diff line
@@ -773,6 +773,7 @@ static void mtd_set_dev_defaults(struct mtd_info *mtd) 


	INIT_LIST_HEAD(&mtd->partitions);

	mutex_init(&mtd->master.partitions_lock);

	mutex_init(&mtd->master.chrdev_lock);

}



/**

include/linux/mtd/mtd.h

+1 −0
Original line number Diff line number Diff line
@@ -229,6 +229,7 @@ struct mtd_part { 
 */

struct mtd_master {

	struct mutex partitions_lock;

	struct mutex chrdev_lock;

	unsigned int suspended : 1;

};