[v2,3/4] scsi: lpfc: fix lpfc_cpu_affinity_check() if no further cpus set

When cpumask_next() the return value is greater than or equal to
nr_cpu_ids, it indicates invalid.

Before commit 596ff4a09b89 ("cpumask: re-introduce constant-sized cpumask
optimizations"), when cpumask_next() returned an invalid cpu, the driver
used the judgment equal to nr_cpu_ids to indicate the invalid cpu, so it
happened to work normally, but this is the wrong approach.

After commit 596ff4a09b89 ("cpumask: re-introduce constant-sized cpumask
optimizations"), these incorrect practices actively buggy, so fix it to
correctly.

Signed-off-by: Vernon Yang <vernon2gm@gmail.com>
---
 drivers/scsi/lpfc/lpfc_init.c | 43 ++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 23 deletions(-)

Hi Vernon,

Is it possible to move the new helper routine lpfc_next_present_cpu
into the lpfc.h header file around where lpfc_next_online_cpu is
defined?

Also, with slight modifications we could use the new
lpfc_next_present_cpu helper routine for the
lpfc_nvmet_setup_io_context() patch as well so that we can contain all
lpfc changes within one patch.

---
 drivers/scsi/lpfc/lpfc.h       | 20 ++++++++++++++++++++
 drivers/scsi/lpfc/lpfc_init.c  | 31 +++++++------------------------
 drivers/scsi/lpfc/lpfc_nvmet.c |  5 +----
 3 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc.h b/drivers/scsi/lpfc/lpfc.h
index cf55f8e3bd9f..f342d6bc5726 100644
--- a/drivers/scsi/lpfc/lpfc.h
+++ b/drivers/scsi/lpfc/lpfc.h
@@ -1737,6 +1737,26 @@ lpfc_next_online_cpu(const struct cpumask
*mask, unsigned int start)

     return cpu_it;
 }
+
+/**
+ * lpfc_next_present_cpu - Finds next present CPU after n
+ * @n: the cpu prior to search
+ *
+ * Note: If no next present cpu, then fallback to first present cpu.
+ *
+ **/
+static inline unsigned int lpfc_next_present_cpu(int n)
+{
+    unsigned int cpu;
+
+    cpu = cpumask_next(n, cpu_present_mask);
+
+    if (cpu >= nr_cpu_ids)
+        cpu = cpumask_first(cpu_present_mask);
+
+    return cpu;
+}
+
 /**
  * lpfc_sli4_mod_hba_eq_delay - update EQ delay
  * @phba: Pointer to HBA context object.
diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c
index 3e1e1d17b2b4..f28af338341f 100644
--- a/drivers/scsi/lpfc/lpfc_init.c
+++ b/drivers/scsi/lpfc/lpfc_init.c
@@ -12560,10 +12560,7 @@ lpfc_cpu_affinity_check(struct lpfc_hba
*phba, int vectors)
                     (new_cpup->eq != LPFC_VECTOR_MAP_EMPTY) &&
                     (new_cpup->phys_id == cpup->phys_id))
                     goto found_same;
-                new_cpu = cpumask_next(
-                    new_cpu, cpu_present_mask);
-                if (new_cpu == nr_cpumask_bits)
-                    new_cpu = first_cpu;
+                new_cpu = lpfc_next_present_cpu(new_cpu);
             }
             /* At this point, we leave the CPU as unassigned */
             continue;
@@ -12575,9 +12572,7 @@ lpfc_cpu_affinity_check(struct lpfc_hba *phba,
int vectors)
              * chance of having multiple unassigned CPU entries
              * selecting the same IRQ.
              */
-            start_cpu = cpumask_next(new_cpu, cpu_present_mask);
-            if (start_cpu == nr_cpumask_bits)
-                start_cpu = first_cpu;
+            start_cpu = lpfc_next_present_cpu(new_cpu);

             lpfc_printf_log(phba, KERN_INFO, LOG_INIT,
                     "3337 Set Affinity: CPU %d "
@@ -12610,10 +12605,7 @@ lpfc_cpu_affinity_check(struct lpfc_hba
*phba, int vectors)
                 if (!(new_cpup->flag & LPFC_CPU_MAP_UNASSIGN) &&
                     (new_cpup->eq != LPFC_VECTOR_MAP_EMPTY))
                     goto found_any;
-                new_cpu = cpumask_next(
-                    new_cpu, cpu_present_mask);
-                if (new_cpu == nr_cpumask_bits)
-                    new_cpu = first_cpu;
+                new_cpu = lpfc_next_present_cpu(new_cpu);
             }
             /* We should never leave an entry unassigned */
             lpfc_printf_log(phba, KERN_ERR, LOG_INIT,
@@ -12629,9 +12621,7 @@ lpfc_cpu_affinity_check(struct lpfc_hba *phba,
int vectors)
              * chance of having multiple unassigned CPU entries
              * selecting the same IRQ.
              */
-            start_cpu = cpumask_next(new_cpu, cpu_present_mask);
-            if (start_cpu == nr_cpumask_bits)
-                start_cpu = first_cpu;
+            start_cpu = lpfc_next_present_cpu(new_cpu);

             lpfc_printf_log(phba, KERN_INFO, LOG_INIT,
                     "3338 Set Affinity: CPU %d "
@@ -12702,9 +12692,7 @@ lpfc_cpu_affinity_check(struct lpfc_hba *phba,
int vectors)
                 new_cpup->core_id == cpup->core_id) {
                 goto found_hdwq;
             }
-            new_cpu = cpumask_next(new_cpu, cpu_present_mask);
-            if (new_cpu == nr_cpumask_bits)
-                new_cpu = first_cpu;
+            new_cpu = lpfc_next_present_cpu(new_cpu);
         }

         /* If we can't match both phys_id and core_id,
@@ -12716,10 +12704,7 @@ lpfc_cpu_affinity_check(struct lpfc_hba
*phba, int vectors)
             if (new_cpup->hdwq != LPFC_VECTOR_MAP_EMPTY &&
                 new_cpup->phys_id == cpup->phys_id)
                 goto found_hdwq;
-
-            new_cpu = cpumask_next(new_cpu, cpu_present_mask);
-            if (new_cpu == nr_cpumask_bits)
-                new_cpu = first_cpu;
+            new_cpu = lpfc_next_present_cpu(new_cpu);
         }

         /* Otherwise just round robin on cfg_hdw_queue */
@@ -12728,9 +12713,7 @@ lpfc_cpu_affinity_check(struct lpfc_hba *phba,
int vectors)
         goto logit;
  found_hdwq:
         /* We found an available entry, copy the IRQ info */
-        start_cpu = cpumask_next(new_cpu, cpu_present_mask);
-        if (start_cpu == nr_cpumask_bits)
-            start_cpu = first_cpu;
+        start_cpu = lpfc_next_present_cpu(new_cpu);
         cpup->hdwq = new_cpup->hdwq;
  logit:
         lpfc_printf_log(phba, KERN_INFO, LOG_INIT,
diff --git a/drivers/scsi/lpfc/lpfc_nvmet.c b/drivers/scsi/lpfc/lpfc_nvmet.c
index 7517dd55fe91..2d8ac2ceb6f3 100644
--- a/drivers/scsi/lpfc/lpfc_nvmet.c
+++ b/drivers/scsi/lpfc/lpfc_nvmet.c
@@ -1620,10 +1620,7 @@ lpfc_nvmet_setup_io_context(struct lpfc_hba *phba)
             cpu = cpumask_first(cpu_present_mask);
             continue;
         }
-        cpu = cpumask_next(cpu, cpu_present_mask);
-        if (cpu == nr_cpu_ids)
-            cpu = cpumask_first(cpu_present_mask);
-
+        cpu = lpfc_next_present_cpu(cpu);
     }

     for_each_present_cpu(i) {