LU-12299 libcfs: fix panic for too large cpu partions

If cpu partions larger than online cpus, following calcuation
will be 0:

num = num_online_cpus() / ncpt;

And it will trigger following panic in cfs_cpt_choose_ncpus()

	LASSERT(number > 0);

We actually did not support this, instead of panic
it, return failure is better.

Also fix a invalid pointer access if we failed to init @cfs_cpt_table,
as it will be converted to ERR_PTR() if error happen.

Change-Id: I49daadd8f0c7d22aa78d08248d8c085781740768
Signed-off-by: Wang Shilong <wshilong@ddn.com>
Reviewed-on: https://review.whamcloud.com/34864
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Gu Zheng <gzheng@ddn.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/libcfs/libcfs/libcfs_cpu.c b/libcfs/libcfs/libcfs_cpu.c
index 6eb9591..e183986 100644 (file)
--- a/libcfs/libcfs/libcfs_cpu.c
+++ b/libcfs/libcfs/libcfs_cpu.c
@@ -868,7 +868,14 @@ static struct cfs_cpt_table *cfs_cpt_table_create(int ncpt)
        if (ncpt <= 0)
                ncpt = num;
 
-       if (ncpt > num_online_cpus() || ncpt > 4 * num) {
+       if (ncpt > num_online_cpus()) {
+               rc = -EINVAL;
+               CERROR("libcfs: CPU partition count %d > cores %d: rc = %d\n",
+                      ncpt, num_online_cpus(), rc);
+               goto failed;
+       }
+
+       if (ncpt > 4 * num) {
                CWARN("CPU partition number %d is larger than suggested value (%d), your system may have performance issue or run out of memory while under pressure\n",
                      ncpt, num);
        }
@@ -1230,7 +1237,7 @@ int cfs_cpu_init(void)
 failed_alloc_table:
        put_online_cpus();
 
-       if (cfs_cpt_table)
+       if (!IS_ERR_OR_NULL(cfs_cpt_table))
                cfs_cpt_table_free(cfs_cpt_table);
 
 #ifdef CONFIG_HOTPLUG_CPU