Hi,
On Wed, Apr 10, 2019 at 7:31 AM Sebastian Andrzej Siewior
<bigeasy@xxxxxxxxxxxxx> wrote:
>
> There is no difference between spinlock_t and raw_spinlock_t for !RT
> kernels. trie_update_elem() will allocate memory while holding ->lock
> which is not possible on RT kernels.
I am new to RT kernel. For !RT kernel, it is OK to hold a lock and call
malloc with GFP_ATOMIC. Is this different for RT kernel?
Thanks,
Song
>
> Make the ->lock a spinlock_t.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> ---
> kernel/bpf/lpm_trie.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c
> index 93a5cbbde421c..2ceb32452b594 100644
> --- a/kernel/bpf/lpm_trie.c
> +++ b/kernel/bpf/lpm_trie.c
> @@ -37,7 +37,7 @@ struct lpm_trie {
> size_t n_entries;
> size_t max_prefixlen;
> size_t data_size;
> - raw_spinlock_t lock;
> + spinlock_t lock;
> };
>
> /* This trie implements a longest prefix match algorithm that can be used to
> @@ -318,7 +318,7 @@ static int trie_update_elem(struct bpf_map *map,
> if (key->prefixlen > trie->max_prefixlen)
> return -EINVAL;
>
> - raw_spin_lock_irqsave(&trie->lock, irq_flags);
> + spin_lock_irqsave(&trie->lock, irq_flags);
>
> /* Allocate and fill a new node */
>
> @@ -425,7 +425,7 @@ static int trie_update_elem(struct bpf_map *map,
> kfree(im_node);
> }
>
> - raw_spin_unlock_irqrestore(&trie->lock, irq_flags);
> + spin_unlock_irqrestore(&trie->lock, irq_flags);
>
> return ret;
> }
> @@ -445,7 +445,7 @@ static int trie_delete_elem(struct bpf_map *map, void *_key)
> if (key->prefixlen > trie->max_prefixlen)
> return -EINVAL;
>
> - raw_spin_lock_irqsave(&trie->lock, irq_flags);
> + spin_lock_irqsave(&trie->lock, irq_flags);
>
> /* Walk the tree looking for an exact key/length match and keeping
> * track of the path we traverse. We will need to know the node
> @@ -521,7 +521,7 @@ static int trie_delete_elem(struct bpf_map *map, void *_key)
> kfree_rcu(node, rcu);
>
> out:
> - raw_spin_unlock_irqrestore(&trie->lock, irq_flags);
> + spin_unlock_irqrestore(&trie->lock, irq_flags);
>
> return ret;
> }
> @@ -583,7 +583,7 @@ static struct bpf_map *trie_alloc(union bpf_attr *attr)
> if (ret)
> goto out_err;
>
> - raw_spin_lock_init(&trie->lock);
> + spin_lock_init(&trie->lock);
>
> return &trie->map;
> out_err:
> --
> 2.20.1
>
