Commit f58423ae authored by Lorenz Bauer's avatar Lorenz Bauer Committed by Daniel Borkmann
Browse files

bpf, sockmap: Add locking annotations to iterator 



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: 03653515 ("net: Allow iterating sockmap and sockhash")
Reported-by: default avatarkernel test robot <lkp@intel.com>
Signed-off-by: default avatarLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Acked-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20201012091850.67452-1-lmb@cloudflare.com
parent e688c3db

net/core/sock_map.c

+8 −0
Original line number Diff line number Diff line
@@ -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);

CRA Git | Maintained and supported by SUSTech CRA and CCSE