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Simplify flow control.

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Also add explicit comment why libc cannot simply rely on open(2)
failure in capability mode.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2017-07-28 12:22:32 +00:00
parent ec92fc8085
commit d00ed7642f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=321652
1 changed files with 11 additions and 12 deletions
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23
lib/libc/x86/sys/__vdso_gettc.c
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@ -197,12 +197,17 @@ __vdso_init_hpet(uint32_t u)
if (old_map != NULL)
return;
if (cap_getmode(&mode) == 0 && mode != 0)
goto fail;
fd = _open(devname, O_RDONLY);
if (fd == -1)
goto fail;
/*
* Explicitely check for the capability mode to avoid
* triggering trap_enocap on the device open by absolute path.
*/
if ((cap_getmode(&mode) == 0 && mode != 0) ||
(fd = _open(devname, O_RDONLY)) == -1) {
/* Prevent the caller from re-entering. */
atomic_cmpset_rel_ptr((volatile uintptr_t *)&hpet_dev_map[u],
(uintptr_t)old_map, (uintptr_t)MAP_FAILED);
return;
}
new_map = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_SHARED, fd, 0);
_close(fd);
@ -210,12 +215,6 @@ __vdso_init_hpet(uint32_t u)
(uintptr_t)old_map, (uintptr_t)new_map) == 0 &&
new_map != MAP_FAILED)
munmap((void *)new_map, PAGE_SIZE);
return;
fail:
/* Prevent the caller from re-entering. */
atomic_cmpset_rel_ptr((volatile uintptr_t *)&hpet_dev_map[u],
(uintptr_t)old_map, (uintptr_t)MAP_FAILED);
}
#ifdef WANT_HYPERV