Re: [PATCH] lightnvm: missing nvm_lock acquire

Matias
2015-11-24T18:36:33Z

On 11/24/2015 04:24 PM, Wenwei Tao wrote:
> To avoid race conditions, traverse dev, media manager,
> and targeet lists and also register, unregister entries
> to/from them, should be always under the nvm_lock control.
>
> Signed-off-by: Wenwei Tao <ww.tao0320@gmail.com>
> ---
> drivers/lightnvm/core.c | 19 +++++++++++++------
> 1 file changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
> index f659e60..39aec3a 100644
> --- a/drivers/lightnvm/core.c
> +++ b/drivers/lightnvm/core.c
> @@ -333,19 +333,19 @@ EXPORT_SYMBOL(nvm_register);
>
> void nvm_unregister(char *disk_name)
> {
> + down_write(&nvm_lock);
> struct nvm_dev *dev = nvm_find_nvm_dev(disk_name);

In nvm_find_nvm_dev, can we instead replace it with
list_for_each_entry_safe. Then we are sure that we won't hit a missing
element, and will make the other cases significantly cleaner.

>
> if (!dev) {
> pr_err("nvm: could not find device %s to unregister\n",
> disk_name);
> + up_write(&nvm_lock);
> return;
> }
>
> - nvm_exit(dev);
> -
> - down_write(&nvm_lock);
> list_del(&dev->devices);
> up_write(&nvm_lock);
> + nvm_exit(dev);
> }
> EXPORT_SYMBOL(nvm_unregister);
>
> @@ -365,12 +365,15 @@ static int nvm_create_target(struct nvm_dev *dev,
> void *targetdata;
> int ret = 0;
>
> + down_write(&nvm_lock);
> if (!dev->mt) {
> /* register with device with a supported NVM manager */
> list_for_each_entry(mt, &nvm_mgrs, list) {

Same with this one?