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bpf, sockmap: Add locking annotations to iterator

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The sparse checker currently outputs the following warnings:

    include/linux/rcupdate.h:632:9: sparse: sparse: context imbalance in 'sock_hash_seq_start' - wrong count at exit
    include/linux/rcupdate.h:632:9: sparse: sparse: context imbalance in 'sock_map_seq_start' - wrong count at exit

Add the necessary __acquires and __release annotations to make the
iterator locking schema palatable to sparse. Also add __must_hold
for good measure.

The kernel codebase uses both __acquires(rcu) and __acquires(RCU).
I couldn't find any guidance which one is preferred, so I used
what is easier to type out.

Fixes: 0365351524 ("net: Allow iterating sockmap and sockhash")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20201012091850.67452-1-lmb@cloudflare.com
This commit is contained in:
Lorenz Bauer 2020-10-12 11:18:50 +02:00 committed by Daniel Borkmann
parent e688c3db7c
commit f58423aeab
1 changed files with 8 additions and 0 deletions
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8
net/core/sock_map.c
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@ -745,6 +745,7 @@ static void *sock_map_seq_lookup_elem(struct sock_map_seq_info *info)
}
static void *sock_map_seq_start(struct seq_file *seq, loff_t *pos)
__acquires(rcu)
{
struct sock_map_seq_info *info = seq->private;
@ -757,6 +758,7 @@ static void *sock_map_seq_start(struct seq_file *seq, loff_t *pos)
}
static void *sock_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
__must_hold(rcu)
{
struct sock_map_seq_info *info = seq->private;
@ -767,6 +769,7 @@ static void *sock_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
}
static int sock_map_seq_show(struct seq_file *seq, void *v)
__must_hold(rcu)
{
struct sock_map_seq_info *info = seq->private;
struct bpf_iter__sockmap ctx = {};
@ -789,6 +792,7 @@ static int sock_map_seq_show(struct seq_file *seq, void *v)
}
static void sock_map_seq_stop(struct seq_file *seq, void *v)
__releases(rcu)
{
if (!v)
(void)sock_map_seq_show(seq, NULL);
@ -1353,6 +1357,7 @@ static void *sock_hash_seq_find_next(struct sock_hash_seq_info *info,
}
static void *sock_hash_seq_start(struct seq_file *seq, loff_t *pos)
__acquires(rcu)
{
struct sock_hash_seq_info *info = seq->private;
@ -1365,6 +1370,7 @@ static void *sock_hash_seq_start(struct seq_file *seq, loff_t *pos)
}
static void *sock_hash_seq_next(struct seq_file *seq, void *v, loff_t *pos)
__must_hold(rcu)
{
struct sock_hash_seq_info *info = seq->private;
@ -1373,6 +1379,7 @@ static void *sock_hash_seq_next(struct seq_file *seq, void *v, loff_t *pos)
}
static int sock_hash_seq_show(struct seq_file *seq, void *v)
__must_hold(rcu)
{
struct sock_hash_seq_info *info = seq->private;
struct bpf_iter__sockmap ctx = {};
@ -1396,6 +1403,7 @@ static int sock_hash_seq_show(struct seq_file *seq, void *v)
}
static void sock_hash_seq_stop(struct seq_file *seq, void *v)
__releases(rcu)
{
if (!v)
(void)sock_hash_seq_show(seq, NULL);