On 21/03/2017 07:50, Jitendra Kolhe wrote:
> 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.ko...@hpe.com>
> ---
> util/oslib-posix.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/util/oslib-posix.c b/util/oslib-posix.c
> index 3fe6089..4d9189e 100644
> --- a/util/oslib-posix.c
> +++ b/util/oslib-posix.c
> @@ -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);
>
Queued, thanks.
Paolo
