| Message ID | 20221103212524.865762-2-dima@arista.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | net/tcp: Dynamically disable TCP-MD5 static key | expand |
On Thu, Nov 03, 2022 at 09:25:22PM +0000, Dmitry Safonov wrote: > A helper to add another user for an existing enabled static key. Utter lack of clue what for. > +/*** > + * static_key_fast_inc - adds a user for a static key > + * @key: static key that must be already enabled > + * > + * The caller must make sure that the static key can't get disabled while > + * in this function. It doesn't patch jump labels, only adds a user to > + * an already enabled static key. > + */ > +static inline void static_key_fast_inc(struct static_key *key) > +{ > + STATIC_KEY_CHECK_USE(key); > + WARN_ON_ONCE(atomic_read(&key->enabled) < 1); > + atomic_inc(&key->enabled); > +} And no, that's racy as heck. We have things like atomic_inc_not_zero(), I suggest looking into it.
Hi Dmitry,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on f2f32f8af2b0ca9d619e5183eae3eed431793baf]
url: https://github.com/intel-lab-lkp/linux/commits/Dmitry-Safonov/net-tcp-Dynamically-disable-TCP-MD5-static-key/20221104-052738
base: f2f32f8af2b0ca9d619e5183eae3eed431793baf
patch link: https://lore.kernel.org/r/20221103212524.865762-2-dima%40arista.com
patch subject: [PATCH v2 1/3] jump_label: Add static_key_fast_inc()
config: powerpc-allyesconfig
compiler: powerpc-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/bff5ecacd7c0f1e5d610c025726a6c5cb992e828
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Dmitry-Safonov/net-tcp-Dynamically-disable-TCP-MD5-static-key/20221104-052738
git checkout bff5ecacd7c0f1e5d610c025726a6c5cb992e828
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=powerpc prepare
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
All error/warnings (new ones prefixed by >>):
In file included from arch/powerpc/include/asm/page.h:256,
from arch/powerpc/include/asm/thread_info.h:13,
from include/linux/thread_info.h:60,
from arch/powerpc/include/asm/ptrace.h:328,
from arch/powerpc/include/asm/hw_irq.h:12,
from arch/powerpc/include/asm/irqflags.h:12,
from include/linux/irqflags.h:16,
from include/asm-generic/cmpxchg-local.h:6,
from arch/powerpc/include/asm/cmpxchg.h:526,
from arch/powerpc/include/asm/atomic.h:11,
from include/linux/atomic.h:7,
from include/linux/jump_label.h:78,
from include/linux/dynamic_debug.h:6,
from include/linux/printk.h:566,
from include/asm-generic/bug.h:22,
from arch/powerpc/include/asm/bug.h:158,
from include/linux/bug.h:5,
from include/linux/fortify-string.h:5,
from include/linux/string.h:253,
from include/linux/uuid.h:12,
from include/linux/mod_devicetable.h:13,
from scripts/mod/devicetable-offsets.c:3:
arch/powerpc/include/asm/page_32.h: In function 'clear_page':
>> arch/powerpc/include/asm/page_32.h:48:9: error: implicit declaration of function 'WARN_ON' [-Werror=implicit-function-declaration]
48 | WARN_ON((unsigned long)addr & (L1_CACHE_BYTES - 1));
| ^~~~~~~
In file included from arch/powerpc/include/asm/hw_breakpoint.h:12,
from arch/powerpc/include/asm/processor.h:43,
from arch/powerpc/include/asm/thread_info.h:46:
arch/powerpc/include/asm/cpu_has_feature.h: At top level:
>> arch/powerpc/include/asm/cpu_has_feature.h:21:31: error: array type has incomplete element type 'struct static_key_true'
21 | extern struct static_key_true cpu_feature_keys[NUM_CPU_FTR_KEYS];
| ^~~~~~~~~~~~~~~~
arch/powerpc/include/asm/cpu_has_feature.h: In function 'cpu_has_feature':
>> arch/powerpc/include/asm/cpu_has_feature.h:32:14: error: 'static_key_initialized' undeclared (first use in this function)
32 | if (!static_key_initialized) {
| ^~~~~~~~~~~~~~~~~~~~~~
arch/powerpc/include/asm/cpu_has_feature.h:32:14: note: each undeclared identifier is reported only once for each function it appears in
>> arch/powerpc/include/asm/cpu_has_feature.h:46:16: error: implicit declaration of function 'static_branch_likely' [-Werror=implicit-function-declaration]
46 | return static_branch_likely(&cpu_feature_keys[i]);
| ^~~~~~~~~~~~~~~~~~~~
>> arch/powerpc/include/asm/cpu_has_feature.h:25:13: warning: variable 'i' set but not used [-Wunused-but-set-variable]
25 | int i;
| ^
include/linux/thread_info.h: In function 'check_copy_size':
>> include/linux/thread_info.h:233:13: error: implicit declaration of function 'WARN_ON_ONCE' [-Werror=implicit-function-declaration]
233 | if (WARN_ON_ONCE(bytes > INT_MAX))
| ^~~~~~~~~~~~
include/linux/jump_label.h: In function 'static_key_fast_inc':
include/linux/jump_label.h:83:35: error: implicit declaration of function 'WARN' [-Werror=implicit-function-declaration]
83 | #define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized, \
| ^~~~
include/linux/jump_label.h:250:9: note: in expansion of macro 'STATIC_KEY_CHECK_USE'
250 | STATIC_KEY_CHECK_USE(key);
| ^~~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
make[2]: *** [scripts/Makefile.build:118: scripts/mod/devicetable-offsets.s] Error 1
make[2]: Target 'scripts/mod/' not remade because of errors.
make[1]: *** [Makefile:1269: prepare0] Error 2
make[1]: Target 'prepare' not remade because of errors.
make: *** [Makefile:231: __sub-make] Error 2
make: Target 'prepare' not remade because of errors.
vim +/static_key_initialized +32 arch/powerpc/include/asm/cpu_has_feature.h
4db7327194dba0 Kevin Hao 2016-07-23 20
4db7327194dba0 Kevin Hao 2016-07-23 @21 extern struct static_key_true cpu_feature_keys[NUM_CPU_FTR_KEYS];
4db7327194dba0 Kevin Hao 2016-07-23 22
4db7327194dba0 Kevin Hao 2016-07-23 23 static __always_inline bool cpu_has_feature(unsigned long feature)
4db7327194dba0 Kevin Hao 2016-07-23 24 {
4db7327194dba0 Kevin Hao 2016-07-23 @25 int i;
4db7327194dba0 Kevin Hao 2016-07-23 26
b5fa0f7f88edcd Michael Ellerman 2017-01-24 27 #ifndef __clang__ /* clang can't cope with this */
4db7327194dba0 Kevin Hao 2016-07-23 28 BUILD_BUG_ON(!__builtin_constant_p(feature));
b5fa0f7f88edcd Michael Ellerman 2017-01-24 29 #endif
4db7327194dba0 Kevin Hao 2016-07-23 30
c812c7d8f1470a Aneesh Kumar K.V 2016-07-23 31 #ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
c812c7d8f1470a Aneesh Kumar K.V 2016-07-23 @32 if (!static_key_initialized) {
c812c7d8f1470a Aneesh Kumar K.V 2016-07-23 33 printk("Warning! cpu_has_feature() used prior to jump label init!\n");
c812c7d8f1470a Aneesh Kumar K.V 2016-07-23 34 dump_stack();
c812c7d8f1470a Aneesh Kumar K.V 2016-07-23 35 return early_cpu_has_feature(feature);
c812c7d8f1470a Aneesh Kumar K.V 2016-07-23 36 }
c812c7d8f1470a Aneesh Kumar K.V 2016-07-23 37 #endif
c812c7d8f1470a Aneesh Kumar K.V 2016-07-23 38
4db7327194dba0 Kevin Hao 2016-07-23 39 if (CPU_FTRS_ALWAYS & feature)
4db7327194dba0 Kevin Hao 2016-07-23 40 return true;
4db7327194dba0 Kevin Hao 2016-07-23 41
4db7327194dba0 Kevin Hao 2016-07-23 42 if (!(CPU_FTRS_POSSIBLE & feature))
4db7327194dba0 Kevin Hao 2016-07-23 43 return false;
4db7327194dba0 Kevin Hao 2016-07-23 44
4db7327194dba0 Kevin Hao 2016-07-23 45 i = __builtin_ctzl(feature);
4db7327194dba0 Kevin Hao 2016-07-23 @46 return static_branch_likely(&cpu_feature_keys[i]);
4db7327194dba0 Kevin Hao 2016-07-23 47 }
4db7327194dba0 Kevin Hao 2016-07-23 48 #else
eed5fae00593ab Christophe Leroy 2021-03-10 49 static __always_inline bool cpu_has_feature(unsigned long feature)
b92a226e528423 Kevin Hao 2016-07-23 50 {
b92a226e528423 Kevin Hao 2016-07-23 51 return early_cpu_has_feature(feature);
b92a226e528423 Kevin Hao 2016-07-23 52 }
4db7327194dba0 Kevin Hao 2016-07-23 53 #endif
b92a226e528423 Kevin Hao 2016-07-23 54
Hi Dmitry,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on f2f32f8af2b0ca9d619e5183eae3eed431793baf]
url: https://github.com/intel-lab-lkp/linux/commits/Dmitry-Safonov/net-tcp-Dynamically-disable-TCP-MD5-static-key/20221104-052738
base: f2f32f8af2b0ca9d619e5183eae3eed431793baf
patch link: https://lore.kernel.org/r/20221103212524.865762-2-dima%40arista.com
patch subject: [PATCH v2 1/3] jump_label: Add static_key_fast_inc()
config: mips-allyesconfig
compiler: mips-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/bff5ecacd7c0f1e5d610c025726a6c5cb992e828
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Dmitry-Safonov/net-tcp-Dynamically-disable-TCP-MD5-static-key/20221104-052738
git checkout bff5ecacd7c0f1e5d610c025726a6c5cb992e828
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=mips prepare
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
In file included from include/linux/dynamic_debug.h:6,
from include/linux/printk.h:566,
from include/asm-generic/bug.h:22,
from arch/mips/include/asm/bug.h:42,
from include/linux/bug.h:5,
from include/linux/fortify-string.h:5,
from include/linux/string.h:253,
from include/linux/uuid.h:12,
from include/linux/mod_devicetable.h:13,
from scripts/mod/devicetable-offsets.c:3:
include/linux/jump_label.h: In function 'static_key_fast_inc':
>> include/linux/jump_label.h:83:35: error: implicit declaration of function 'WARN' [-Werror=implicit-function-declaration]
83 | #define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized, \
| ^~~~
include/linux/jump_label.h:250:9: note: in expansion of macro 'STATIC_KEY_CHECK_USE'
250 | STATIC_KEY_CHECK_USE(key);
| ^~~~~~~~~~~~~~~~~~~~
>> include/linux/jump_label.h:251:9: error: implicit declaration of function 'WARN_ON_ONCE' [-Werror=implicit-function-declaration]
251 | WARN_ON_ONCE(atomic_read(&key->enabled) < 1);
| ^~~~~~~~~~~~
cc1: some warnings being treated as errors
make[2]: *** [scripts/Makefile.build:118: scripts/mod/devicetable-offsets.s] Error 1
make[2]: Target 'scripts/mod/' not remade because of errors.
make[1]: *** [Makefile:1269: prepare0] Error 2
make[1]: Target 'prepare' not remade because of errors.
make: *** [Makefile:231: __sub-make] Error 2
make: Target 'prepare' not remade because of errors.
vim +/WARN +83 include/linux/jump_label.h
c4b2c0c5f647aa Hannes Frederic Sowa 2013-10-19 82
5cdda5117e125e Borislav Petkov 2017-10-18 @83 #define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized, \
5cdda5117e125e Borislav Petkov 2017-10-18 84 "%s(): static key '%pS' used before call to jump_label_init()", \
5cdda5117e125e Borislav Petkov 2017-10-18 85 __func__, (key))
d430d3d7e646eb Jason Baron 2011-03-16 86
c5905afb0ee655 Ingo Molnar 2012-02-24 87 struct static_key {
d430d3d7e646eb Jason Baron 2011-03-16 88 atomic_t enabled;
cd27ccfc727e99 Masahiro Yamada 2022-02-14 89 #ifdef CONFIG_JUMP_LABEL
3821fd35b58dba Jason Baron 2017-02-03 90 /*
b17ef2ed624aa7 Steven Rostedt (VMware 2017-03-02 91) * Note:
b17ef2ed624aa7 Steven Rostedt (VMware 2017-03-02 92) * To make anonymous unions work with old compilers, the static
b17ef2ed624aa7 Steven Rostedt (VMware 2017-03-02 93) * initialization of them requires brackets. This creates a dependency
b17ef2ed624aa7 Steven Rostedt (VMware 2017-03-02 94) * on the order of the struct with the initializers. If any fields
b17ef2ed624aa7 Steven Rostedt (VMware 2017-03-02 95) * are added, STATIC_KEY_INIT_TRUE and STATIC_KEY_INIT_FALSE may need
b17ef2ed624aa7 Steven Rostedt (VMware 2017-03-02 96) * to be modified.
b17ef2ed624aa7 Steven Rostedt (VMware 2017-03-02 97) *
3821fd35b58dba Jason Baron 2017-02-03 98 * bit 0 => 1 if key is initially true
3821fd35b58dba Jason Baron 2017-02-03 99 * 0 if initially false
3821fd35b58dba Jason Baron 2017-02-03 100 * bit 1 => 1 if points to struct static_key_mod
3821fd35b58dba Jason Baron 2017-02-03 101 * 0 if points to struct jump_entry
3821fd35b58dba Jason Baron 2017-02-03 102 */
3821fd35b58dba Jason Baron 2017-02-03 103 union {
3821fd35b58dba Jason Baron 2017-02-03 104 unsigned long type;
d430d3d7e646eb Jason Baron 2011-03-16 105 struct jump_entry *entries;
c5905afb0ee655 Ingo Molnar 2012-02-24 106 struct static_key_mod *next;
3821fd35b58dba Jason Baron 2017-02-03 107 };
cd27ccfc727e99 Masahiro Yamada 2022-02-14 108 #endif /* CONFIG_JUMP_LABEL */
d430d3d7e646eb Jason Baron 2011-03-16 109 };
d430d3d7e646eb Jason Baron 2011-03-16 110
c0ccf6f99e3a43 Anton Blanchard 2015-04-09 111 #endif /* __ASSEMBLY__ */
c0ccf6f99e3a43 Anton Blanchard 2015-04-09 112
e9666d10a5677a Masahiro Yamada 2018-12-31 113 #ifdef CONFIG_JUMP_LABEL
c0ccf6f99e3a43 Anton Blanchard 2015-04-09 114 #include <asm/jump_label.h>
9ae033aca8d600 Ard Biesheuvel 2018-09-18 115
9ae033aca8d600 Ard Biesheuvel 2018-09-18 116 #ifndef __ASSEMBLY__
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 117 #ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 118
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 119 struct jump_entry {
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 120 s32 code;
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 121 s32 target;
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 122 long key; // key may be far away from the core kernel under KASLR
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 123 };
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 124
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 125 static inline unsigned long jump_entry_code(const struct jump_entry *entry)
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 126 {
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 127 return (unsigned long)&entry->code + entry->code;
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 128 }
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 129
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 130 static inline unsigned long jump_entry_target(const struct jump_entry *entry)
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 131 {
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 132 return (unsigned long)&entry->target + entry->target;
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 133 }
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 134
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 135 static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 136 {
19483677684b6c Ard Biesheuvel 2018-09-18 137 long offset = entry->key & ~3L;
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 138
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 139 return (struct static_key *)((unsigned long)&entry->key + offset);
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 140 }
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 141
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 142 #else
9ae033aca8d600 Ard Biesheuvel 2018-09-18 143
9ae033aca8d600 Ard Biesheuvel 2018-09-18 144 static inline unsigned long jump_entry_code(const struct jump_entry *entry)
9ae033aca8d600 Ard Biesheuvel 2018-09-18 145 {
9ae033aca8d600 Ard Biesheuvel 2018-09-18 146 return entry->code;
9ae033aca8d600 Ard Biesheuvel 2018-09-18 147 }
9ae033aca8d600 Ard Biesheuvel 2018-09-18 148
9ae033aca8d600 Ard Biesheuvel 2018-09-18 149 static inline unsigned long jump_entry_target(const struct jump_entry *entry)
9ae033aca8d600 Ard Biesheuvel 2018-09-18 150 {
9ae033aca8d600 Ard Biesheuvel 2018-09-18 151 return entry->target;
9ae033aca8d600 Ard Biesheuvel 2018-09-18 152 }
9ae033aca8d600 Ard Biesheuvel 2018-09-18 153
9ae033aca8d600 Ard Biesheuvel 2018-09-18 154 static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
9ae033aca8d600 Ard Biesheuvel 2018-09-18 155 {
19483677684b6c Ard Biesheuvel 2018-09-18 156 return (struct static_key *)((unsigned long)entry->key & ~3UL);
9ae033aca8d600 Ard Biesheuvel 2018-09-18 157 }
9ae033aca8d600 Ard Biesheuvel 2018-09-18 158
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 159 #endif
50ff18ab497aa2 Ard Biesheuvel 2018-09-18 160
9ae033aca8d600 Ard Biesheuvel 2018-09-18 161 static inline bool jump_entry_is_branch(const struct jump_entry *entry)
9ae033aca8d600 Ard Biesheuvel 2018-09-18 162 {
9ae033aca8d600 Ard Biesheuvel 2018-09-18 163 return (unsigned long)entry->key & 1UL;
9ae033aca8d600 Ard Biesheuvel 2018-09-18 164 }
9ae033aca8d600 Ard Biesheuvel 2018-09-18 165
9ae033aca8d600 Ard Biesheuvel 2018-09-18 166 static inline bool jump_entry_is_init(const struct jump_entry *entry)
9ae033aca8d600 Ard Biesheuvel 2018-09-18 167 {
19483677684b6c Ard Biesheuvel 2018-09-18 168 return (unsigned long)entry->key & 2UL;
9ae033aca8d600 Ard Biesheuvel 2018-09-18 169 }
9ae033aca8d600 Ard Biesheuvel 2018-09-18 170
5af0ea293d78c8 Peter Zijlstra 2021-05-06 171 static inline void jump_entry_set_init(struct jump_entry *entry, bool set)
9ae033aca8d600 Ard Biesheuvel 2018-09-18 172 {
5af0ea293d78c8 Peter Zijlstra 2021-05-06 173 if (set)
19483677684b6c Ard Biesheuvel 2018-09-18 174 entry->key |= 2;
5af0ea293d78c8 Peter Zijlstra 2021-05-06 175 else
5af0ea293d78c8 Peter Zijlstra 2021-05-06 176 entry->key &= ~2;
9ae033aca8d600 Ard Biesheuvel 2018-09-18 177 }
9ae033aca8d600 Ard Biesheuvel 2018-09-18 178
fa5e5dc39669b4 Peter Zijlstra 2021-05-06 179 static inline int jump_entry_size(struct jump_entry *entry)
fa5e5dc39669b4 Peter Zijlstra 2021-05-06 180 {
fa5e5dc39669b4 Peter Zijlstra 2021-05-06 181 #ifdef JUMP_LABEL_NOP_SIZE
fa5e5dc39669b4 Peter Zijlstra 2021-05-06 182 return JUMP_LABEL_NOP_SIZE;
fa5e5dc39669b4 Peter Zijlstra 2021-05-06 183 #else
fa5e5dc39669b4 Peter Zijlstra 2021-05-06 184 return arch_jump_entry_size(entry);
fa5e5dc39669b4 Peter Zijlstra 2021-05-06 185 #endif
fa5e5dc39669b4 Peter Zijlstra 2021-05-06 186 }
fa5e5dc39669b4 Peter Zijlstra 2021-05-06 187
9ae033aca8d600 Ard Biesheuvel 2018-09-18 188 #endif
c0ccf6f99e3a43 Anton Blanchard 2015-04-09 189 #endif
c0ccf6f99e3a43 Anton Blanchard 2015-04-09 190
c0ccf6f99e3a43 Anton Blanchard 2015-04-09 191 #ifndef __ASSEMBLY__
bf5438fca2950b Jason Baron 2010-09-17 192
bf5438fca2950b Jason Baron 2010-09-17 193 enum jump_label_type {
76b235c6bcb160 Peter Zijlstra 2015-07-24 194 JUMP_LABEL_NOP = 0,
76b235c6bcb160 Peter Zijlstra 2015-07-24 195 JUMP_LABEL_JMP,
bf5438fca2950b Jason Baron 2010-09-17 196 };
bf5438fca2950b Jason Baron 2010-09-17 197
bf5438fca2950b Jason Baron 2010-09-17 198 struct module;
bf5438fca2950b Jason Baron 2010-09-17 199
e9666d10a5677a Masahiro Yamada 2018-12-31 200 #ifdef CONFIG_JUMP_LABEL
4c5ea0a9cd02d6 Paolo Bonzini 2016-06-21 201
a1efb01feca597 Peter Zijlstra 2015-07-24 202 #define JUMP_TYPE_FALSE 0UL
a1efb01feca597 Peter Zijlstra 2015-07-24 203 #define JUMP_TYPE_TRUE 1UL
3821fd35b58dba Jason Baron 2017-02-03 204 #define JUMP_TYPE_LINKED 2UL
3821fd35b58dba Jason Baron 2017-02-03 205 #define JUMP_TYPE_MASK 3UL
c5905afb0ee655 Ingo Molnar 2012-02-24 206
c5905afb0ee655 Ingo Molnar 2012-02-24 207 static __always_inline bool static_key_false(struct static_key *key)
c5905afb0ee655 Ingo Molnar 2012-02-24 208 {
11276d5306b8e5 Peter Zijlstra 2015-07-24 209 return arch_static_branch(key, false);
c5905afb0ee655 Ingo Molnar 2012-02-24 210 }
d430d3d7e646eb Jason Baron 2011-03-16 211
c5905afb0ee655 Ingo Molnar 2012-02-24 212 static __always_inline bool static_key_true(struct static_key *key)
c5905afb0ee655 Ingo Molnar 2012-02-24 213 {
11276d5306b8e5 Peter Zijlstra 2015-07-24 214 return !arch_static_branch(key, true);
c5905afb0ee655 Ingo Molnar 2012-02-24 215 }
c5905afb0ee655 Ingo Molnar 2012-02-24 216
bf5438fca2950b Jason Baron 2010-09-17 217 extern struct jump_entry __start___jump_table[];
bf5438fca2950b Jason Baron 2010-09-17 218 extern struct jump_entry __stop___jump_table[];
bf5438fca2950b Jason Baron 2010-09-17 219
97ce2c88f9ad42 Jeremy Fitzhardinge 2011-10-12 220 extern void jump_label_init(void);
91bad2f8d30574 Jason Baron 2010-10-01 221 extern void jump_label_lock(void);
91bad2f8d30574 Jason Baron 2010-10-01 222 extern void jump_label_unlock(void);
bf5438fca2950b Jason Baron 2010-09-17 223 extern void arch_jump_label_transform(struct jump_entry *entry,
bf5438fca2950b Jason Baron 2010-09-17 224 enum jump_label_type type);
c2ba8a15f310d9 Daniel Bristot de Oliveira 2019-06-12 225 extern bool arch_jump_label_transform_queue(struct jump_entry *entry,
c2ba8a15f310d9 Daniel Bristot de Oliveira 2019-06-12 226 enum jump_label_type type);
c2ba8a15f310d9 Daniel Bristot de Oliveira 2019-06-12 227 extern void arch_jump_label_transform_apply(void);
4c3ef6d79328c0 Jason Baron 2010-09-17 228 extern int jump_label_text_reserved(void *start, void *end);
c5905afb0ee655 Ingo Molnar 2012-02-24 229 extern void static_key_slow_inc(struct static_key *key);
c5905afb0ee655 Ingo Molnar 2012-02-24 230 extern void static_key_slow_dec(struct static_key *key);
ce48c146495a1a Peter Zijlstra 2018-01-22 231 extern void static_key_slow_inc_cpuslocked(struct static_key *key);
ce48c146495a1a Peter Zijlstra 2018-01-22 232 extern void static_key_slow_dec_cpuslocked(struct static_key *key);
1f69bf9c613760 Jason Baron 2016-08-03 233 extern int static_key_count(struct static_key *key);
1f69bf9c613760 Jason Baron 2016-08-03 234 extern void static_key_enable(struct static_key *key);
1f69bf9c613760 Jason Baron 2016-08-03 235 extern void static_key_disable(struct static_key *key);
5a40527f8f0798 Marc Zyngier 2017-08-01 236 extern void static_key_enable_cpuslocked(struct static_key *key);
5a40527f8f0798 Marc Zyngier 2017-08-01 237 extern void static_key_disable_cpuslocked(struct static_key *key);
fdfd42892f311e Ard Biesheuvel 2022-06-15 238 extern enum jump_label_type jump_label_init_type(struct jump_entry *entry);
c5905afb0ee655 Ingo Molnar 2012-02-24 239
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 240 /***
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 241 * static_key_fast_inc - adds a user for a static key
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 242 * @key: static key that must be already enabled
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 243 *
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 244 * The caller must make sure that the static key can't get disabled while
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 245 * in this function. It doesn't patch jump labels, only adds a user to
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 246 * an already enabled static key.
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 247 */
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 248 static inline void static_key_fast_inc(struct static_key *key)
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 249 {
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 250 STATIC_KEY_CHECK_USE(key);
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 @251 WARN_ON_ONCE(atomic_read(&key->enabled) < 1);
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 252 atomic_inc(&key->enabled);
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 253 }
bff5ecacd7c0f1 Dmitry Safonov 2022-11-03 254
On 11/3/22 21:41, Peter Zijlstra wrote: > On Thu, Nov 03, 2022 at 09:25:22PM +0000, Dmitry Safonov wrote: >> A helper to add another user for an existing enabled static key. > > Utter lack of clue what for. > >> +/*** >> + * static_key_fast_inc - adds a user for a static key >> + * @key: static key that must be already enabled >> + * >> + * The caller must make sure that the static key can't get disabled while >> + * in this function. It doesn't patch jump labels, only adds a user to >> + * an already enabled static key. >> + */ >> +static inline void static_key_fast_inc(struct static_key *key) >> +{ >> + STATIC_KEY_CHECK_USE(key); >> + WARN_ON_ONCE(atomic_read(&key->enabled) < 1); >> + atomic_inc(&key->enabled); >> +} > > And no, that's racy as heck. We have things like atomic_inc_not_zero(), > I suggest looking into it. Thanks for the review, I'll look into that for v3. Thanks, Dmitry
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index 570831ca9951..cb6c722c4816 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -75,6 +75,8 @@ #include <linux/types.h> #include <linux/compiler.h> +#include <linux/atomic.h> +#include <linux/bug.h> extern bool static_key_initialized; @@ -235,6 +237,21 @@ extern void static_key_enable_cpuslocked(struct static_key *key); extern void static_key_disable_cpuslocked(struct static_key *key); extern enum jump_label_type jump_label_init_type(struct jump_entry *entry); +/*** + * static_key_fast_inc - adds a user for a static key + * @key: static key that must be already enabled + * + * The caller must make sure that the static key can't get disabled while + * in this function. It doesn't patch jump labels, only adds a user to + * an already enabled static key. + */ +static inline void static_key_fast_inc(struct static_key *key) +{ + STATIC_KEY_CHECK_USE(key); + WARN_ON_ONCE(atomic_read(&key->enabled) < 1); + atomic_inc(&key->enabled); +} + /* * We should be using ATOMIC_INIT() for initializing .enabled, but * the inclusion of atomic.h is problematic for inclusion of jump_label.h @@ -251,9 +268,6 @@ extern enum jump_label_type jump_label_init_type(struct jump_entry *entry); #else /* !CONFIG_JUMP_LABEL */ -#include <linux/atomic.h> -#include <linux/bug.h> - static __always_inline int static_key_count(struct static_key *key) { return arch_atomic_read(&key->enabled); @@ -290,6 +304,7 @@ static inline void static_key_slow_dec(struct static_key *key) atomic_dec(&key->enabled); } +#define static_key_fast_inc(key) static_key_slow_inc(key) #define static_key_slow_inc_cpuslocked(key) static_key_slow_inc(key) #define static_key_slow_dec_cpuslocked(key) static_key_slow_dec(key)
A helper to add another user for an existing enabled static key. Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Jason Baron <jbaron@akamai.com> Cc: Josh Poimboeuf <jpoimboe@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Dmitry Safonov <dima@arista.com> --- include/linux/jump_label.h | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-)