LU-9859 libcfs: Fix using smp_processor_id() in preemptible context

[fs/lustre-release.git] / libcfs / libcfs / libcfs_cpu.c

diff --git a/libcfs/libcfs/libcfs_cpu.c b/libcfs/libcfs/libcfs_cpu.c
index 9fac258..aa2c6b4 100644 (file)
--- a/libcfs/libcfs/libcfs_cpu.c
+++ b/libcfs/libcfs/libcfs_cpu.c
@@ -32,8 +32,8 @@
 
 #include <linux/cpu.h>
 #include <linux/sched.h>
-#include <libcfs/libcfs_cpu.h>
 #include <libcfs/libcfs.h>
+#include <libcfs/libcfs_cpu.h>
 
 /** virtual processing unit */
 struct cfs_cpu_partition {
@@ -844,13 +844,17 @@ out:
        return rc;
 }
 
-#define CPT_WEIGHT_MIN 4
+#define CPT_WEIGHT_MIN 4u
 
-static int cfs_cpt_num_estimate(void)
+static unsigned int cfs_cpt_num_estimate(void)
 {
-       int nthr = cpumask_weight(topology_sibling_cpumask(smp_processor_id()));
-       int ncpu = num_online_cpus();
-       int ncpt = 1;
+       unsigned int nthr;
+       unsigned int ncpu = num_online_cpus();
+       unsigned int ncpt = 1;
+
+       preempt_disable();
+       nthr = cpumask_weight(topology_sibling_cpumask(smp_processor_id()));
+       preempt_enable();
 
        if (ncpu > CPT_WEIGHT_MIN)
                for (ncpt = 2; ncpu > 2 * nthr * ncpt; ncpt++)
@@ -860,7 +864,7 @@ static int cfs_cpt_num_estimate(void)
        /* config many CPU partitions on 32-bit system could consume
         * too much memory
         */
-       ncpt = min(2, ncpt);
+       ncpt = min(2U, ncpt);
 #endif
        while (ncpu % ncpt)
                ncpt--; /* worst case is 1 */