From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47453) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cqDaT-00079L-NS for qemu-devel@nongnu.org; Tue, 21 Mar 2017 02:48:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cqDaQ-0000fQ-Ks for qemu-devel@nongnu.org; Tue, 21 Mar 2017 02:48:09 -0400 Received: from g2t2354.austin.hpe.com ([15.233.44.27]:22976) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cqDaQ-0000Wq-FH for qemu-devel@nongnu.org; Tue, 21 Mar 2017 02:48:06 -0400 From: Jitendra Kolhe Date: Tue, 21 Mar 2017 02:50:06 -0400 Message-Id: <1490079006-32495-1-git-send-email-jitendra.kolhe@hpe.com> Subject: [Qemu-devel] [PATCH] mem-prealloc: fix sysconf(_SC_NPROCESSORS_ONLN) failure case. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: pbonzini@redhat.com, peter.maydell@linaro.org, armbru@redhat.com, stefanha@redhat.com, kwolf@redhat.com, renganathan.meenakshisundaram@hpe.com, mohan_parthasarathy@hpe.com, jitendra.kolhe@hpe.com 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 --- 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); -- 1.8.3.1