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

This warning show up with kernels that enable preemptible
BUG: using smp_processor_id() in preemptible [00000000] code: ...

Change it to disable preemption around smp_processor_id().

Change is apart of:
Linux-commit: 67bc8c33ec14f8290c6883a7d6237e213709561a

Change-Id: I41f7a1d3aa22240d3669f94ae92a192d219cca52
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/38810
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/libcfs/libcfs/libcfs_cpu.c b/libcfs/libcfs/libcfs_cpu.c
index f7d1bde..aa2c6b4 100644 (file)
--- a/libcfs/libcfs/libcfs_cpu.c
+++ b/libcfs/libcfs/libcfs_cpu.c
@@ -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 */