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| author | Jakub Kicinski <kuba@kernel.org> | 2022-12-02 02:53:08 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-12-02 02:53:09 +0300 |
| commit | 39e9d6f3cc7cd39712b7bb61bcc6fea02931f9a6 (patch) | |
| tree | cb38a0fc6b3639c8f123d4540ac26080b445b89e /include/linux | |
| parent | 19833ae2703d4b5ca184db50a11351cfa611da01 (diff) | |
| parent | c5b8b515a211377e78bb7807fe3e6e7212626545 (diff) | |
| download | linux-39e9d6f3cc7cd39712b7bb61bcc6fea02931f9a6.tar.xz | |
Merge branch 'net-tcp-dynamically-disable-tcp-md5-static-key'
Dmitry Safonov says:
====================
net/tcp: Dynamically disable TCP-MD5 static key
The static key introduced by commit 6015c71e656b ("tcp: md5: add
tcp_md5_needed jump label") is a fast-path optimization aimed at
avoiding a cache line miss.
Once an MD5 key is introduced in the system the static key is enabled
and never disabled. Address this by disabling the static key when
the last tcp_md5sig_info in system is destroyed.
Previously it was submitted as a part of TCP-AO patches set [1].
Now in attempt to split 36 patches submission, I send this independently.
Version 5:
https://lore.kernel.org/all/20221122185534.308643-1-dima@arista.com/T/#u
Version 4:
https://lore.kernel.org/all/20221115211905.1685426-1-dima@arista.com/T/#u
Version 3:
https://lore.kernel.org/all/20221111212320.1386566-1-dima@arista.com/T/#u
Version 2:
https://lore.kernel.org/all/20221103212524.865762-1-dima@arista.com/T/#u
Version 1:
https://lore.kernel.org/all/20221102211350.625011-1-dima@arista.com/T/#u
[1]: https://lore.kernel.org/all/20221027204347.529913-1-dima@arista.com/T/#u
====================
Link: https://lore.kernel.org/r/20221123173859.473629-1-dima@arista.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/jump_label.h | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index 570831ca9951..4e968ebadce6 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -224,9 +224,10 @@ extern bool arch_jump_label_transform_queue(struct jump_entry *entry, enum jump_label_type type); extern void arch_jump_label_transform_apply(void); extern int jump_label_text_reserved(void *start, void *end); -extern void static_key_slow_inc(struct static_key *key); +extern bool static_key_slow_inc(struct static_key *key); +extern bool static_key_fast_inc_not_disabled(struct static_key *key); extern void static_key_slow_dec(struct static_key *key); -extern void static_key_slow_inc_cpuslocked(struct static_key *key); +extern bool static_key_slow_inc_cpuslocked(struct static_key *key); extern void static_key_slow_dec_cpuslocked(struct static_key *key); extern int static_key_count(struct static_key *key); extern void static_key_enable(struct static_key *key); @@ -278,11 +279,23 @@ static __always_inline bool static_key_true(struct static_key *key) return false; } -static inline void static_key_slow_inc(struct static_key *key) +static inline bool static_key_fast_inc_not_disabled(struct static_key *key) { + int v; + STATIC_KEY_CHECK_USE(key); - atomic_inc(&key->enabled); + /* + * Prevent key->enabled getting negative to follow the same semantics + * as for CONFIG_JUMP_LABEL=y, see kernel/jump_label.c comment. + */ + v = atomic_read(&key->enabled); + do { + if (v < 0 || (v + 1) < 0) + return false; + } while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v + 1))); + return true; } +#define static_key_slow_inc(key) static_key_fast_inc_not_disabled(key) static inline void static_key_slow_dec(struct static_key *key) { |