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SubjectRe: [tip:bkl/drivers] nvram: Drop the BKL from nvram_open()


On Wed, 14 Oct 2009, tip-bot for Ingo Molnar wrote:

> Commit-ID: 83cb16727085b18191f45eb0ede6bf1f97d67a7a
> Gitweb: http://git.kernel.org/tip/83cb16727085b18191f45eb0ede6bf1f97d67a7a
> Author: Ingo Molnar <mingo@elte.hu>
> AuthorDate: Wed, 14 Oct 2009 17:48:38 +0200
> Committer: Ingo Molnar <mingo@elte.hu>
> CommitDate: Wed, 14 Oct 2009 17:54:03 +0200
>
> nvram: Drop the BKL from nvram_open()
>
> It's safe to remove the BKL from nvram_open(): there's no open()
> versus read() races: nvram_init() is very simple and race-free,
> it registers the device then puts it into /proc - there's no
> state init to race with.
>
> Cc: Wim Van Sebroeck <wim@iguana.be>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> LKML-Reference: <1255116426-7270-1-git-send-email-fweisbec@gmail.com>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> ---
> drivers/char/nvram.c | 3 ---
> 1 files changed, 0 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/char/nvram.c b/drivers/char/nvram.c
> index 2100a8f..7cf4518 100644
> --- a/drivers/char/nvram.c
> +++ b/drivers/char/nvram.c
> @@ -329,14 +329,12 @@ static int nvram_ioctl(struct inode *inode, struct file *file,
>
> static int nvram_open(struct inode *inode, struct file *file)
> {
> - lock_kernel();
> spin_lock(&nvram_state_lock);
>
> if ((nvram_open_cnt && (file->f_flags & O_EXCL)) ||
> (nvram_open_mode & NVRAM_EXCL) ||
> ((file->f_mode & FMODE_WRITE) && (nvram_open_mode & NVRAM_WRITE))) {
> spin_unlock(&nvram_state_lock);
> - unlock_kernel();
> return -EBUSY;
> }
>
> @@ -347,7 +345,6 @@ static int nvram_open(struct inode *inode, struct file *file)
> nvram_open_cnt++;
>
> spin_unlock(&nvram_state_lock);
> - unlock_kernel();
>
> return 0;
> }
> --
> To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>

This patch and a previous one remove the bkl from the open and llseek
functions. We can also convert to an unlocked_ioctl

From 8eab1862b12cc851dc2c811261dda7a22d13e83a Mon Sep 17 00:00:00 2001
From: John Kacur <jkacur@redhat.com>
Date: Wed, 21 Oct 2009 21:57:19 +0200
Subject: [PATCH] nvram: Convert nvram_ioctl to unlocked_ioctl

After removing the BKL from open, we can also convert nvram_ioctl to
an unlocked_ioctl. It has it's only spin_lock, and doesn't rely on the BKL

Signed-off-by: John Kacur <jkacur@redhat.com>
---
drivers/char/nvram.c | 17 ++++++++---------
1 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/char/nvram.c b/drivers/char/nvram.c
index 7cf4518..6c34279 100644
--- a/drivers/char/nvram.c
+++ b/drivers/char/nvram.c
@@ -290,8 +290,7 @@ checksum_err:
return -EIO;
}

-static int nvram_ioctl(struct inode *inode, struct file *file,
- unsigned int cmd, unsigned long arg)
+static long nvram_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
int i;

@@ -412,13 +411,13 @@ static int nvram_add_proc_fs(void)
#endif /* CONFIG_PROC_FS */

static const struct file_operations nvram_fops = {
- .owner = THIS_MODULE,
- .llseek = nvram_llseek,
- .read = nvram_read,
- .write = nvram_write,
- .ioctl = nvram_ioctl,
- .open = nvram_open,
- .release = nvram_release,
+ .owner = THIS_MODULE,
+ .llseek = nvram_llseek,
+ .read = nvram_read,
+ .write = nvram_write,
+ .unlocked_ioctl = nvram_ioctl,
+ .open = nvram_open,
+ .release = nvram_release,
};

static struct miscdevice nvram_dev = {
--
1.6.0.6


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