2021-02-17 21:31:47

by Alexander Sverdlin

Subject: [PATCH 1/2] mtd: char: Drop mtd_mutex usage from mtdchar_open()

From: Alexander Sverdlin <[email protected]>

It looks unnecessary in the function, remove it from the function
having in mind to remove it completely.

Signed-off-by: Alexander Sverdlin <[email protected]>
---
drivers/mtd/mtdchar.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 323035d..f31390d 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -58,13 +58,10 @@ static int mtdchar_open(struct inode *inode, struct file *file)
if ((file->f_mode & FMODE_WRITE) && (minor & 1))
return -EACCES;

- mutex_lock(&mtd_mutex);
mtd = get_mtd_device(NULL, devnum);

- if (IS_ERR(mtd)) {
- ret = PTR_ERR(mtd);
- goto out;
- }
+ if (IS_ERR(mtd))
+ return PTR_ERR(mtd);

if (mtd->type == MTD_ABSENT) {
ret = -ENODEV;
@@ -84,13 +81,10 @@ static int mtdchar_open(struct inode *inode, struct file *file)
}
mfi->mtd = mtd;
file->private_data = mfi;
- mutex_unlock(&mtd_mutex);
return 0;

out1:
put_mtd_device(mtd);
-out:
- mutex_unlock(&mtd_mutex);
return ret;
} /* mtdchar_open */

--
2.10.2

2021-02-17 21:31:47

by Alexander Sverdlin

Subject: [PATCH 2/2] mtd: char: Get rid of Big MTD Lock

From: Alexander Sverdlin <[email protected]>

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: Alexander Sverdlin <[email protected]>
---
drivers/mtd/mtdchar.c | 14 ++++++++------
drivers/mtd/mtdcore.c | 1 +
include/linux/mtd/mtd.h | 1 +
3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index f31390d..57c4a2f 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -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;
}
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 2d6423d..0b09597 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -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);
}

/**
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 157357e..ceabc2c 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -229,6 +229,7 @@ struct mtd_part {
*/
struct mtd_master {
struct mutex partitions_lock;
+ struct mutex chrdev_lock;
unsigned int suspended : 1;
};

--
2.10.2

2021-03-04 06:37:04

by Miquel Raynal

Subject: Re: [PATCH 2/2] mtd: char: Get rid of Big MTD Lock

On Wed, 2021-02-17 at 21:18:45 UTC, Alexander A Sverdlin wrote:
> From: Alexander Sverdlin <[email protected]>
>
> 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: Alexander Sverdlin <[email protected]>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.

Miquel

2021-03-04 06:38:36

by Miquel Raynal

Subject: Re: [PATCH 1/2] mtd: char: Drop mtd_mutex usage from mtdchar_open()

On Wed, 2021-02-17 at 21:18:44 UTC, Alexander A Sverdlin wrote:
> From: Alexander Sverdlin <[email protected]>
>
> It looks unnecessary in the function, remove it from the function
> having in mind to remove it completely.
>
> Signed-off-by: Alexander Sverdlin <[email protected]>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.

Miquel