Messages in this thread | | | Date | Sun, 17 Dec 2017 22:34:19 +0800 | From | kbuild test robot <> | Subject | [tip:WIP.x86/pti.entry 10/39] include/linux/compiler.h:344:2: error: implicit declaration of function 'smp_read_barrier_depends' |
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tree: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP.x86/pti.entry head: 6891282dd3ab7fead975ed52d0f7f8da37ab96a5 commit: c2bc66082e1048c7573d72e62f597bdc5ce13fea [10/39] locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE() config: h8300-h8300h-sim_defconfig (attached as .config) compiler: h8300-linux-gcc (GCC) 7.2.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout c2bc66082e1048c7573d72e62f597bdc5ce13fea # save the attached .config to linux build tree make.cross ARCH=h8300
All error/warnings (new ones prefixed by >>):
In file included from include/uapi/linux/stddef.h:2:0, from include/linux/stddef.h:5, from arch/h8300/kernel/asm-offsets.c:12: include/linux/list.h: In function 'list_empty': >> include/linux/compiler.h:344:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration] smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ ^ >> include/linux/compiler.h:347:22: note: in expansion of macro '__READ_ONCE' #define READ_ONCE(x) __READ_ONCE(x, 1) ^~~~~~~~~~~ >> include/linux/list.h:203:9: note: in expansion of macro 'READ_ONCE' return READ_ONCE(head->next) == head; ^~~~~~~~~ cc1: some warnings being treated as errors make[2]: *** [arch/h8300/kernel/asm-offsets.s] Error 1 make[2]: Target '__build' not remade because of errors. make[1]: *** [prepare0] Error 2 make[1]: Target 'prepare' not remade because of errors. make: *** [sub-make] Error 2
vim +/smp_read_barrier_depends +344 include/linux/compiler.h
313 314 /* 315 * Prevent the compiler from merging or refetching reads or writes. The 316 * compiler is also forbidden from reordering successive instances of 317 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the 318 * compiler is aware of some particular ordering. One way to make the 319 * compiler aware of ordering is to put the two invocations of READ_ONCE, 320 * WRITE_ONCE or ACCESS_ONCE() in different C statements. 321 * 322 * In contrast to ACCESS_ONCE these two macros will also work on aggregate 323 * data types like structs or unions. If the size of the accessed data 324 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) 325 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at 326 * least two memcpy()s: one for the __builtin_memcpy() and then one for 327 * the macro doing the copy of variable - '__u' allocated on the stack. 328 * 329 * Their two major use cases are: (1) Mediating communication between 330 * process-level code and irq/NMI handlers, all running on the same CPU, 331 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 332 * mutilate accesses that either do not require ordering or that interact 333 * with an explicit memory barrier or atomic instruction that provides the 334 * required ordering. 335 */ 336 337 #define __READ_ONCE(x, check) \ 338 ({ \ 339 union { typeof(x) __val; char __c[1]; } __u; \ 340 if (check) \ 341 __read_once_size(&(x), __u.__c, sizeof(x)); \ 342 else \ 343 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ > 344 smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ 345 __u.__val; \ 346 }) > 347 #define READ_ONCE(x) __READ_ONCE(x, 1) 348
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