Re: [PATCH V2] lightnvm: protect target type list with correct locks

[Matias BjÃrling]

On 09/18/2017 09:53 AM, Javier GonzÃlez wrote:
> > On 16 Sep 2017, at 20.39, Rakesh Pandit <rakesh@xxxxxxxxxx> wrote:
> >
> > nvm_tgt_types list was protected by wrong lock for NVM_INFO ioctl call
> > and can race with addition or removal of target types.  Also
> > unregistering target type was not protected correctly.
> >
> > Fixes: 5cd907853 ("lightnvm: remove nested lock conflict with mm")
> > Signed-off-by: Rakesh Pandit <rakesh@xxxxxxxxxx>
> > ---
> >
> > V2: also add correct lock while unregistering and fix "Fixes" tag at
> > end.  Note I found these while investigating another issue and
> > skimming the core code but worth fixing.
> >
> > drivers/lightnvm/core.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
> > index 9f9a137..1b8338d 100644
> > --- a/drivers/lightnvm/core.c
> > +++ b/drivers/lightnvm/core.c
> > @@ -589,9 +589,9 @@ void nvm_unregister_tgt_type(struct nvm_tgt_type *tt)
> > 	if (!tt)
> > 		return;
> >
> > -	down_write(&nvm_lock);
> > +	down_write(&nvm_tgtt_lock);
> > 	list_del(&tt->list);
> > -	up_write(&nvm_lock);
> > +	up_write(&nvm_tgtt_lock);
> > }
> > EXPORT_SYMBOL(nvm_unregister_tgt_type);
> >
> > @@ -1190,7 +1190,7 @@ static long nvm_ioctl_info(struct file *file, void __user *arg)
> > 	info->version[1] = NVM_VERSION_MINOR;
> > 	info->version[2] = NVM_VERSION_PATCH;
> >
> > -	down_write(&nvm_lock);
> > +	down_write(&nvm_tgtt_lock);
> > 	list_for_each_entry(tt, &nvm_tgt_types, list) {
> > 		struct nvm_ioctl_info_tgt *tgt = &info->tgts[tgt_iter];
> >
> > @@ -1203,7 +1203,7 @@ static long nvm_ioctl_info(struct file *file, void __user *arg)
> > 	}
> >
> > 	info->tgtsize = tgt_iter;
> > -	up_write(&nvm_lock);
> > +	up_write(&nvm_tgtt_lock);
> >
> > 	if (copy_to_user(arg, info, sizeof(struct nvm_ioctl_info))) {
> > 		kfree(info);
> > --
> > 2.7.4
>
> LGTM.
>
> Reviewed-by: Javier GonzÃlez <javier@xxxxxxxxxxxx>

Thanks Rakesh.