lightnvm: pblk: fix two sleep-in-atomic-context bugs

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@gmail.com>
Reviewed-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/lightnvm/pblk-recovery.c b/drivers/lightnvm/pblk-recovery.c
index 8036c3eb637240bbab660e25c47d9e1cd8a14f59..2526722304bb7cd10a199b40008e479b9542e2ce 100644 (file)
--- a/drivers/lightnvm/pblk-recovery.c
+++ b/drivers/lightnvm/pblk-recovery.c
@@ -966,12 +966,14 @@ next:
                }
        }
 
-       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) {
@@ -979,8 +981,8 @@ next:
                        l_mg->data_next->type = PBLK_LINETYPE_DATA;
                        is_next = 1;
                }
+               spin_unlock(&l_mg->free_lock);
        }
-       spin_unlock(&l_mg->free_lock);
 
        if (is_next)
                pblk_line_erase(pblk, l_mg->data_next);