On Wed, Sep 5, 2018 at 10:40 AM Jia-Ju Bai <baijiaju1990@xxxxxxxxx> wrote:
>
> The driver may sleep with holding a spinlock.
>
> The function call paths (from bottom to top) in Linux-4.16 are:
>
> [FUNC] nvm_dev_dma_alloc(GFP_KERNEL)
> drivers/lightnvm/pblk-core.c, 754:
> nvm_dev_dma_alloc in pblk_line_submit_smeta_io
> drivers/lightnvm/pblk-core.c, 1048:
> pblk_line_submit_smeta_io in pblk_line_init_bb
> drivers/lightnvm/pblk-core.c, 1434:
> pblk_line_init_bb in pblk_line_replace_data
> drivers/lightnvm/pblk-recovery.c, 980:
> pblk_line_replace_data in pblk_recov_l2p
> drivers/lightnvm/pblk-recovery.c, 976:
> spin_lock in pblk_recov_l2p
>
> [FUNC] bio_map_kern(GFP_KERNEL)
> drivers/lightnvm/pblk-core.c, 762:
> bio_map_kern in pblk_line_submit_smeta_io
> drivers/lightnvm/pblk-core.c, 1048:
> pblk_line_submit_smeta_io in pblk_line_init_bb
> drivers/lightnvm/pblk-core.c, 1434:
> pblk_line_init_bb in pblk_line_replace_data
> drivers/lightnvm/pblk-recovery.c, 980:
> pblk_line_replace_data in pblk_recov_l2p
> drivers/lightnvm/pblk-recovery.c, 976:
> spin_lock in pblk_recov_l2p
>
> To fix these bugs, the call to pblk_line_replace_data()
> is moved out of the spinlock protection.
>
> These bugs are found by my static analysis tool DSAC.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
> ---
> v2:
> * Move the call to pblk_line_replace_data() out of the spinlock
> protection, instead of v1 that changes GFP_KERNEL to GFP_ATOMIC in
> the calls to bio_map_kern() and nvm_dev_dma_alloc().
> Thanks Javier for good advice.
> ---
> drivers/lightnvm/pblk-recovery.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/lightnvm/pblk-recovery.c b/drivers/lightnvm/pblk-recovery.c
> index 3a5069183859..5fde414d78bb 100644
> --- a/drivers/lightnvm/pblk-recovery.c
> +++ b/drivers/lightnvm/pblk-recovery.c
> @@ -955,12 +955,14 @@ struct pblk_line *pblk_recov_l2p(struct pblk *pblk)
> }
> }
>
> - spin_lock(&l_mg->free_lock);
> if (!open_lines) {
> + spin_lock(&l_mg->free_lock);
> WARN_ON_ONCE(!test_and_clear_bit(meta_line,
> &l_mg->meta_bitmap));
> + spin_unlock(&l_mg->free_lock);
> pblk_line_replace_data(pblk);
> } else {
> + spin_lock(&l_mg->free_lock);
> /* Allocate next line for preparation */
> l_mg->data_next = pblk_line_get(pblk);
> if (l_mg->data_next) {
> @@ -968,8 +970,8 @@ struct pblk_line *pblk_recov_l2p(struct pblk *pblk)
> l_mg->data_next->type = PBLK_LINETYPE_DATA;
> is_next = 1;
> }
> + spin_unlock(&l_mg->free_lock);
> }
> - spin_unlock(&l_mg->free_lock);
Wouldn't the most straight forward solution here to not take the lock?
As pblk is doing all the recovery sequentially during initialization,
I don't see the
reason for grabbing the lock.
>
> if (is_next)
> pblk_line_erase(pblk, l_mg->data_next);
> --
> 2.17.0
>
