Re: [PATCH v4 bpf-next 2/9] bpf: Add map side support for bpf timers.
flat view
From: Martin KaFai Lau <hidden>
Date: 2021-07-02 06:24:12
Also in:
bpf
On Thu, Jul 01, 2021 at 12:20:37PM -0700, Alexei Starovoitov wrote: [ ... ]
quoted hunk ↗ jump to hunk
+static void htab_free_prealloced_timers(struct bpf_htab *htab) +{ + u32 num_entries = htab->map.max_entries; + int i; + + if (likely(!map_value_has_timer(&htab->map))) + return; + if (htab_has_extra_elems(htab)) + num_entries += num_possible_cpus(); + + for (i = 0; i < num_entries; i++) { + struct htab_elem *elem; + + elem = get_htab_elem(htab, i); + bpf_timer_cancel_and_free(elem->key + + round_up(htab->map.key_size, 8) + + htab->map.timer_off); + cond_resched(); + } +} +
[ ... ]
quoted hunk ↗ jump to hunk
+static void htab_free_malloced_timers(struct bpf_htab *htab) +{ + int i; + + for (i = 0; i < htab->n_buckets; i++) { + struct hlist_nulls_head *head = select_bucket(htab, i); + struct hlist_nulls_node *n; + struct htab_elem *l; + + hlist_nulls_for_each_entry(l, n, head, hash_node)
It is called from map_release_uref() which is not under rcu. Either a bucket lock or rcu_read_lock is needed here. Another question, can prealloc map does the same thing like here (i.e. walk the buckets) during map_release_uref()?