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Cache the isc_os_ncpu() result

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It was discovered that on some platforms (f.e. Alpine Linux with MUSL)
the result of isc_os_ncpus() call differ when called before and after we
drop privileges.  This commit changes the isc_os_ncpus() call to cache
the result from the first call and thus always return the same value
during the runtime of the named.  The first call to isc_os_ncpus() is
made as soon as possible on the library initalization.
This commit is contained in:
Ondrej Sury 2021-07-12 14:21:21 +02:00 committed by Ondřej Surý
parent e04d69533d
commit 23751fe252
2 changed files with 18 additions and 6 deletions
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2
lib/isc/lib.c
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@ -14,6 +14,7 @@
#include <isc/bind9.h>
#include <isc/lib.h>
#include <isc/mem.h>
#include <isc/os.h>
#include <isc/tls.h>
#include <isc/util.h>
@ -45,6 +46,7 @@ isc__initialize(void) {
isc__mem_initialize();
isc__tls_initialize();
isc__trampoline_initialize();
(void)isc_os_ncpus();
}
void

22
lib/isc/os.c
View file

@ -9,7 +9,12 @@
* information regarding copyright ownership.
*/
#include <isc/once.h>
#include <isc/os.h>
#include <isc/util.h>
static isc_once_t ncpus_once = ISC_ONCE_INIT;
static unsigned int ncpus = 0;
#ifdef HAVE_SYSCONF
@ -46,10 +51,8 @@ sysctl_ncpus(void) {
}
#endif /* if defined(HAVE_SYS_SYSCTL_H) && defined(HAVE_SYSCTLBYNAME) */
unsigned int
isc_os_ncpus(void) {
long ncpus = 0;
static void
ncpus_initialize(void) {
#if defined(HAVE_SYSCONF)
ncpus = sysconf_ncpus();
#endif /* if defined(HAVE_SYSCONF) */
@ -61,6 +64,13 @@ isc_os_ncpus(void) {
if (ncpus <= 0) {
ncpus = 1;
}
return ((unsigned int)ncpus);
}
unsigned int
isc_os_ncpus(void) {
isc_result_t result = isc_once_do(&ncpus_once, ncpus_initialize);
RUNTIME_CHECK(result == ISC_R_SUCCESS);
INSIST(ncpus > 0);
return (ncpus);
}