softirq: s/BUG/WARN_ONCE/ on tasklet SCHED state not set

Replace BUG() with WARN_ONCE() on wrong tasklet state, in order to:

 - increase the verbosity / aid in debugging
 - avoid fatal/unrecoverable state

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210317102012.32399-1-erosca@de.adit-jv.com

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 8b44ab9a2f6935d6a9aad7afeb6e9ae87e789b18..8d56bbf852eaf86a5e68a661d66cac44ff85027c 100644 (file)
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -531,6 +531,18 @@ void __tasklet_hi_schedule(struct tasklet_struct *t)
 }
 EXPORT_SYMBOL(__tasklet_hi_schedule);
 
+static bool tasklet_should_run(struct tasklet_struct *t)
+{
+       if (test_and_clear_bit(TASKLET_STATE_SCHED, &t->state))
+               return true;
+
+       WARN_ONCE(1, "tasklet SCHED state not set: %s %pS\n",
+                 t->use_callback ? "callback" : "func",
+                 t->use_callback ? (void *)t->callback : (void *)t->func);
+
+       return false;
+}
+
 static void tasklet_action_common(struct softirq_action *a,
                                  struct tasklet_head *tl_head,
                                  unsigned int softirq_nr)
@@ -550,13 +562,12 @@ static void tasklet_action_common(struct softirq_action *a,
 
                if (tasklet_trylock(t)) {
                        if (!atomic_read(&t->count)) {
-                               if (!test_and_clear_bit(TASKLET_STATE_SCHED,
-                                                       &t->state))
-                                       BUG();
-                               if (t->use_callback)
-                                       t->callback(t);
-                               else
-                                       t->func(t->data);
+                               if (tasklet_should_run(t)) {
+                                       if (t->use_callback)
+                                               t->callback(t);
+                                       else
+                                               t->func(t->data);
+                               }
                                tasklet_unlock(t);
                                continue;
                        }