sched,tracing: Convert to sched_set_fifo()

One module user of sched_setscheduler() was overlooked and is
obviously causing build failures.

Convert ring_buffer_benchmark to use sched_set_fifo_low() when fifo==1
and sched_set_fifo() when fifo==2. This is a bit of an abuse, but it
makes the thing 'work' again.

Specifically, it enables all combinations that were previously
possible:

  producer higher than consumer
  consumer higher than producer

Fixes: 616d91b68cd5 ("sched: Remove sched_setscheduler*() EXPORTs")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/20200720214918.GM5523@worktop.programming.kicks-ass.net

diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
index 8df0aa81095008bc11d8ed3c7a476fc66ec7f286..78e576575b79ecad5102dd86b53354c76222556b 100644 (file)
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -45,8 +45,8 @@ MODULE_PARM_DESC(write_iteration, "# of writes between timestamp readings");
 static int producer_nice = MAX_NICE;
 static int consumer_nice = MAX_NICE;
 
-static int producer_fifo = -1;
-static int consumer_fifo = -1;
+static int producer_fifo;
+static int consumer_fifo;
 
 module_param(producer_nice, int, 0644);
 MODULE_PARM_DESC(producer_nice, "nice prio for producer");
@@ -55,10 +55,10 @@ module_param(consumer_nice, int, 0644);
 MODULE_PARM_DESC(consumer_nice, "nice prio for consumer");
 
 module_param(producer_fifo, int, 0644);
-MODULE_PARM_DESC(producer_fifo, "fifo prio for producer");
+MODULE_PARM_DESC(producer_fifo, "use fifo for producer: 0 - disabled, 1 - low prio, 2 - fifo");
 
 module_param(consumer_fifo, int, 0644);
-MODULE_PARM_DESC(consumer_fifo, "fifo prio for consumer");
+MODULE_PARM_DESC(consumer_fifo, "use fifo for consumer: 0 - disabled, 1 - low prio, 2 - fifo");
 
 static int read_events;
 
@@ -303,22 +303,22 @@ static void ring_buffer_producer(void)
                trace_printk("ERROR!\n");
 
        if (!disable_reader) {
-               if (consumer_fifo < 0)
+               if (consumer_fifo)
+                       trace_printk("Running Consumer at SCHED_FIFO %s\n",
+                                    consumer_fifo == 1 ? "low" : "high");
+               else
                        trace_printk("Running Consumer at nice: %d\n",
                                     consumer_nice);
-               else
-                       trace_printk("Running Consumer at SCHED_FIFO %d\n",
-                                    consumer_fifo);
        }
-       if (producer_fifo < 0)
+       if (producer_fifo)
+               trace_printk("Running Producer at SCHED_FIFO %s\n",
+                            producer_fifo == 1 ? "low" : "high");
+       else
                trace_printk("Running Producer at nice: %d\n",
                             producer_nice);
-       else
-               trace_printk("Running Producer at SCHED_FIFO %d\n",
-                            producer_fifo);
 
        /* Let the user know that the test is running at low priority */
-       if (producer_fifo < 0 && consumer_fifo < 0 &&
+       if (!producer_fifo && !consumer_fifo &&
            producer_nice == MAX_NICE && consumer_nice == MAX_NICE)
                trace_printk("WARNING!!! This test is running at lowest priority.\n");
 
@@ -455,21 +455,19 @@ static int __init ring_buffer_benchmark_init(void)
         * Run them as low-prio background tasks by default:
         */
        if (!disable_reader) {
-               if (consumer_fifo >= 0) {
-                       struct sched_param param = {
-                               .sched_priority = consumer_fifo
-                       };
-                       sched_setscheduler(consumer, SCHED_FIFO, &param);
-               } else
+               if (consumer_fifo >= 2)
+                       sched_set_fifo(consumer);
+               else if (consumer_fifo == 1)
+                       sched_set_fifo_low(consumer);
+               else
                        set_user_nice(consumer, consumer_nice);
        }
 
-       if (producer_fifo >= 0) {
-               struct sched_param param = {
-                       .sched_priority = producer_fifo
-               };
-               sched_setscheduler(producer, SCHED_FIFO, &param);
-       } else
+       if (producer_fifo >= 2)
+               sched_set_fifo(producer);
+       else if (producer_fifo == 1)
+               sched_set_fifo_low(producer);
+       else
                set_user_nice(producer, producer_nice);
 
        return 0;