* [Qemu-devel] [PATCH] mem-prealloc: fix sysconf(_SC_NPROCESSORS_ONLN) failure case.
@ 2017-03-21 6:50 Jitendra Kolhe
2017-03-24 10:50 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Jitendra Kolhe @ 2017-03-21 6:50 UTC (permalink / raw)
To: qemu-devel
Cc: pbonzini, peter.maydell, armbru, stefanha, kwolf,
renganathan.meenakshisundaram, mohan_parthasarathy,
jitendra.kolhe
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>
---
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] [PATCH] mem-prealloc: fix sysconf(_SC_NPROCESSORS_ONLN) failure case.
2017-03-21 6:50 [Qemu-devel] [PATCH] mem-prealloc: fix sysconf(_SC_NPROCESSORS_ONLN) failure case Jitendra Kolhe
@ 2017-03-24 10:50 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2017-03-24 10:50 UTC (permalink / raw)
To: Jitendra Kolhe, qemu-devel
Cc: peter.maydell, armbru, stefanha, kwolf,
renganathan.meenakshisundaram, mohan_parthasarathy
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.kolhe@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
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2017-03-21 6:50 [Qemu-devel] [PATCH] mem-prealloc: fix sysconf(_SC_NPROCESSORS_ONLN) failure case Jitendra Kolhe
2017-03-24 10:50 ` Paolo Bonzini
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