On Tue, 6 Jan 2015 08:34:07 +0800
xiaomin1 <xiaoming.w...@intel.com> wrote:
> misc_mtx was used to mutex misc_list.
> But file->f_op->open may be blocked by downloading
> firmware in some devices' open.
> So move file->f_op->open out of mutex (misc_mtx)
> in misc_open to avoid this block.
> It also make code more efficiency.
>
> Signed-off-by: Zhang Dongxing <dongxing.zh...@intel.com>
> Signed-off-by: xiaoming wang <xiaoming.w...@intel.com>
> ---
> drivers/char/misc.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/misc.c b/drivers/char/misc.c
> index ffa97d2..289c59e 100644
> --- a/drivers/char/misc.c
> +++ b/drivers/char/misc.c
> @@ -144,7 +144,8 @@ static int misc_open(struct inode * inode, struct file *
> file)
> replace_fops(file, new_fops);
> if (file->f_op->open) {
> file->private_data = c;
> - err = file->f_op->open(inode,file);
> + mutex_unlock(&misc_mtx);
> + return file->f_op->open(inode,file);
> }
This changes all the users of misc device open from singlethreaded to
multi-threaded. Having read through the users I can find this seems safe
and they all seem to have the right checks in place and to assume they
are multi-threaded.
Reviewed-by: Alan Cox <a...@linux.intel.com>
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