Commit dfd0dcc7 authored by Jitendra Kolhe's avatar Jitendra Kolhe Committed by Paolo Bonzini
Browse files

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: default avatarJitendra Kolhe <jitendra.kolhe@hpe.com>
Message-Id: <1490079006-32495-1-git-send-email-jitendra.kolhe@hpe.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 30663fd2

util/oslib-posix.c

+14 −2
Original line number Diff line number Diff line
@@ -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);