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jump_label: Do not use unserialized static_key_enabled() 

Any use of key->enabled (that is static_key_enabled and static_key_count)
outside jump_label_lock should handle its own serialization.  The only
two that are not doing so are the UDP encapsulation static keys.  Change
them to use static_key_enable, which now correctly tests key->enabled under
the jump label lock.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1501601046-35683-3-git-send-email-pbonzini@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Paolo Bonzini 2017-08-01 17:24:05 +02:00 committed by Ingo Molnar
parent 1dbb6704de
commit 7a34bcb8b2
3 changed files with 7 additions and 4 deletions
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5
Documentation/static-keys.txt
View File

@ -149,6 +149,11 @@ static_branch_inc(), will change the branch back to true. Likewise, if the
key is initialized false, a 'static_branch_inc()', will change the branch to
true. And then a 'static_branch_dec()', will again make the branch false.
The state and the reference count can be retrieved with 'static_key_enabled()'
and 'static_key_count()'. In general, if you use these functions, they
should be protected with the same mutex used around the enable/disable
or increment/decrement function.
Where an array of keys is required, it can be defined as::
DEFINE_STATIC_KEY_ARRAY_TRUE(keys, count);

3
net/ipv4/udp.c
View File

@ -1809,8 +1809,7 @@ static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
static struct static_key udp_encap_needed __read_mostly;
void udp_encap_enable(void)
{
if (!static_key_enabled(&udp_encap_needed))
static_key_slow_inc(&udp_encap_needed);
static_key_enable(&udp_encap_needed);
}
EXPORT_SYMBOL(udp_encap_enable);

3
net/ipv6/udp.c
View File

@ -574,8 +574,7 @@ static __inline__ void udpv6_err(struct sk_buff *skb,
static struct static_key udpv6_encap_needed __read_mostly;
void udpv6_encap_enable(void)
{
if (!static_key_enabled(&udpv6_encap_needed))
static_key_slow_inc(&udpv6_encap_needed);
static_key_enable(&udpv6_encap_needed);
}
EXPORT_SYMBOL(udpv6_encap_enable);