Thanks to Jiri Kosina et al...
See the reasons below.
On 04/22/2013 03:32 PM, Jiri Kosina wrote:
> From: Jiri Kosina <jkosina@xxxxxxx>
> Subject: [PATCH 3.0-stable] Revert "sysfs: fix race between readdir and lseek"
>
> This reverts commit 991f76f837bf22c5bb07261cfd86525a0a96650c.
>
> It depends on ef3d0fd27e90f ("vfs: do (nearly) lockless generic_file_llseek")
> which is available only in 3.2+.
>
> When applied on 3.0 codebase, it causes A-A deadlock, whenever anyone does
> seek() on sysfs, as both generic_file_llseek() and sysfs_dir_llseek() obtain
> i_mutex.
>
> Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
> ---
> fs/sysfs/dir.c | 13 +------------
> 1 files changed, 1 insertions(+), 12 deletions(-)
>
> Index: linux-3.0-SLE11-SP3-sysfs-hang-debug/fs/sysfs/dir.c
> ===================================================================
> --- linux-3.0-SLE11-SP3-sysfs-hang-debug.orig/fs/sysfs/dir.c
> +++ linux-3.0-SLE11-SP3-sysfs-hang-debug/fs/sysfs/dir.c
> @@ -961,21 +961,9 @@ static int sysfs_readdir(struct file * f
> return 0;
> }
>
> -static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence)
> -{
> - struct inode *inode = file->f_path.dentry->d_inode;
> - loff_t ret;
> -
> - mutex_lock(&inode->i_mutex);
> - ret = generic_file_llseek(file, offset, whence);
> - mutex_unlock(&inode->i_mutex);
> -
> - return ret;
> -}
> -
> const struct file_operations sysfs_dir_operations = {
> .read = generic_read_dir,
> .readdir = sysfs_readdir,
> .release = sysfs_dir_release,
> - .llseek = sysfs_dir_llseek,
> + .llseek = generic_file_llseek,
> };
>
--
js
suse labs
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