mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-22 18:32:14 +07:00
b2f5de0334
* Test lookup in /proc/self/fd. "map_files" lookup story showed that lookup is not that simple. * Test that all those symlinks open the same file. Check with (st_dev, st_info). * Test that kernel threads do not have anything in their /proc/*/fd/ directory. Now this is where things get interesting. First, kernel threads aren't pinned by /proc/self or equivalent, thus some "atomicity" is required. Second, ->comm can contain whitespace and ')'. No, they are not escaped. Third, the only reliable way to check if process is kernel thread appears to be field #9 in /proc/*/stat. This field is struct task_struct::flags in decimal! Check is done by testing PF_KTHREAD flags like we do in kernel. PF_KTREAD value is a part of userspace ABI !!! Other methods for determining kernel threadness are not reliable: * RSS can be 0 if everything is swapped, even while reading from /proc/self. * ->total_vm CAN BE ZERO if process is finishing munmap(NULL, whole address space); * /proc/*/maps and similar files can be empty because unmapping everything works. Read returning 0 can't distinguish between kernel thread and such suicide process. Link: http://lkml.kernel.org/r/20180505000414.GA15090@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
40 lines
659 B
C
40 lines
659 B
C
#pragma once
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#undef NDEBUG
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#include <assert.h>
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#include <dirent.h>
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#include <errno.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <string.h>
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static inline bool streq(const char *s1, const char *s2)
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{
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return strcmp(s1, s2) == 0;
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}
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static unsigned long long xstrtoull(const char *p, char **end)
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{
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if (*p == '0') {
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*end = (char *)p + 1;
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return 0;
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} else if ('1' <= *p && *p <= '9') {
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unsigned long long val;
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errno = 0;
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val = strtoull(p, end, 10);
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assert(errno == 0);
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return val;
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} else
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assert(0);
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}
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static struct dirent *xreaddir(DIR *d)
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{
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struct dirent *de;
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errno = 0;
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de = readdir(d);
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assert(de || errno == 0);
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return de;
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}
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