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mem-prealloc: fix sysconf(_SC_NPROCESSORS_ONLN) failure case. 

This was spotted by Coverity, in case where sysconf(_SC_NPROCESSORS_ONLN)
fails and returns -1. This results in memset_num_threads getting set to -1.
Which we then pass to g_new0().
The patch replaces MAX_MEM_PREALLOC_THREAD_COUNT macro with a function call
get_memset_num_threads() to handle sysconf() failure gracefully. In case
sysconf() fails, we fall back to single threaded.

(Spotted by Coverity, CID 1372465.)

Signed-off-by: Jitendra Kolhe <jitendra.kolhe@hpe.com>
Message-Id: <1490079006-32495-1-git-send-email-jitendra.kolhe@hpe.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jitendra Kolhe 2017-03-21 02:50:06 -04:00 committed by Paolo Bonzini
parent 30663fd26c
commit dfd0dcc717
1 changed files with 14 additions and 2 deletions
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16
util/oslib-posix.c
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@ -55,7 +55,7 @@
#include "qemu/error-report.h"
#endif
#define MAX_MEM_PREALLOC_THREAD_COUNT (MIN(sysconf(_SC_NPROCESSORS_ONLN), 16))
#define MAX_MEM_PREALLOC_THREAD_COUNT 16
struct MemsetThread {
char *addr;
@ -381,6 +381,18 @@ static void *do_touch_pages(void *arg)
return NULL;
}
static inline int get_memset_num_threads(int smp_cpus)
{
long host_procs = sysconf(_SC_NPROCESSORS_ONLN);
int ret = 1;
if (host_procs > 0) {
ret = MIN(MIN(host_procs, MAX_MEM_PREALLOC_THREAD_COUNT), smp_cpus);
}
/* In case sysconf() fails, we fall back to single threaded */
return ret;
}
static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages,
int smp_cpus)
{
@ -389,7 +401,7 @@ static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages,
int i = 0;
memset_thread_failed = false;
memset_num_threads = MIN(smp_cpus, MAX_MEM_PREALLOC_THREAD_COUNT);
memset_num_threads = get_memset_num_threads(smp_cpus);
memset_thread = g_new0(MemsetThread, memset_num_threads);
numpages_per_thread = (numpages / memset_num_threads);
size_per_thread = (hpagesize * numpages_per_thread);