From: Alexey Dobriyan <adobriyan@xxxxxxxxx> Subject: proc: test /proc/thread-self symlink Same story: I have WIP patch to make it faster, so better have a test as well. Link: http://lkml.kernel.org/r/20180627195209.GC18113@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx> Cc: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/proc/.gitignore | 1 tools/testing/selftests/proc/Makefile | 1 tools/testing/selftests/proc/proc.h | 5 + tools/testing/selftests/proc/thread-self.c | 64 +++++++++++++++++++ 4 files changed, 71 insertions(+) --- a/tools/testing/selftests/proc/.gitignore~proc-test-proc-thread-self-symlink +++ a/tools/testing/selftests/proc/.gitignore @@ -10,3 +10,4 @@ /proc-uptime-002 /read /self +/thread-self --- a/tools/testing/selftests/proc/Makefile~proc-test-proc-thread-self-symlink +++ a/tools/testing/selftests/proc/Makefile @@ -14,5 +14,6 @@ TEST_GEN_PROGS += proc-uptime-001 TEST_GEN_PROGS += proc-uptime-002 TEST_GEN_PROGS += read TEST_GEN_PROGS += self +TEST_GEN_PROGS += thread-self include ../lib.mk --- a/tools/testing/selftests/proc/proc.h~proc-test-proc-thread-self-symlink +++ a/tools/testing/selftests/proc/proc.h @@ -14,6 +14,11 @@ static inline pid_t sys_getpid(void) return syscall(SYS_getpid); } +static inline pid_t sys_gettid(void) +{ + return syscall(SYS_gettid); +} + static inline bool streq(const char *s1, const char *s2) { return strcmp(s1, s2) == 0; --- /dev/null +++ a/tools/testing/selftests/proc/thread-self.c @@ -0,0 +1,64 @@ +/* + * Copyright © 2018 Alexey Dobriyan <adobriyan@xxxxxxxxx> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ +// Test that /proc/thread-self gives correct TGID/PID. +#undef NDEBUG +#include <assert.h> +#include <sched.h> +#include <stdio.h> +#include <unistd.h> +#include <sys/mman.h> +#include <sys/wait.h> + +#include "proc.h" + +int f(void *arg) +{ + char buf1[64], buf2[64]; + pid_t pid, tid; + ssize_t rv; + + pid = sys_getpid(); + tid = sys_gettid(); + snprintf(buf1, sizeof(buf1), "%u/task/%u", pid, tid); + + rv = readlink("/proc/thread-self", buf2, sizeof(buf2)); + assert(rv == strlen(buf1)); + buf2[rv] = '\0'; + assert(streq(buf1, buf2)); + + if (arg) + exit(0); + return 0; +} + +int main(void) +{ + const int PAGE_SIZE = sysconf(_SC_PAGESIZE); + pid_t pid; + void *stack; + + /* main thread */ + f((void *)0); + + stack = mmap(NULL, 2 * PAGE_SIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); + assert(stack != MAP_FAILED); + /* side thread */ + pid = clone(f, stack + PAGE_SIZE, CLONE_THREAD|CLONE_SIGHAND|CLONE_VM, (void *)1); + assert(pid > 0); + pause(); + + return 0; +} _
