mm/kasan/quarantine.c: make quarantine_lock a raw_spinlock_t

The static lock quarantine_lock is used in quarantine.c to protect the
quarantine queue datastructures.  It is taken inside quarantine queue
manipulation routines (quarantine_put(), quarantine_reduce() and
quarantine_remove_cache()), with IRQs disabled.  This is not a problem on
a stock kernel but is problematic on an RT kernel where spin locks are
sleeping spinlocks, which can sleep and can not be acquired with disabled
interrupts.

Convert the quarantine_lock to a raw spinlock_t.  The usage of
quarantine_lock is confined to quarantine.c and the work performed while
the lock is held is used for debug purpose.

[bigeasy@linutronix.de: slightly altered the commit message]
Link: http://lkml.kernel.org/r/20181010214945.5owshc3mlrh74z4b@linutronix.de
Signed-off-by: Clark Williams <williams@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index 3a8ddf8..b209dba 100644 (file)
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -103,7 +103,7 @@ static int quarantine_head;
 static int quarantine_tail;
 /* Total size of all objects in global_quarantine across all batches. */
 static unsigned long quarantine_size;
-static DEFINE_SPINLOCK(quarantine_lock);
+static DEFINE_RAW_SPINLOCK(quarantine_lock);
 DEFINE_STATIC_SRCU(remove_cache_srcu);
 
 /* Maximum size of the global queue. */
@@ -190,7 +190,7 @@ void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache)
        if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) {
                qlist_move_all(q, &temp);
 
-               spin_lock(&quarantine_lock);
+               raw_spin_lock(&quarantine_lock);
                WRITE_ONCE(quarantine_size, quarantine_size + temp.bytes);
                qlist_move_all(&temp, &global_quarantine[quarantine_tail]);
                if (global_quarantine[quarantine_tail].bytes >=
@@ -203,7 +203,7 @@ void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache)
                        if (new_tail != quarantine_head)
                                quarantine_tail = new_tail;
                }
-               spin_unlock(&quarantine_lock);
+               raw_spin_unlock(&quarantine_lock);
        }
 
        local_irq_restore(flags);
@@ -230,7 +230,7 @@ void quarantine_reduce(void)
         * expected case).
         */
        srcu_idx = srcu_read_lock(&remove_cache_srcu);
-       spin_lock_irqsave(&quarantine_lock, flags);
+       raw_spin_lock_irqsave(&quarantine_lock, flags);
 
        /*
         * Update quarantine size in case of hotplug. Allocate a fraction of
@@ -254,7 +254,7 @@ void quarantine_reduce(void)
                        quarantine_head = 0;
        }
 
-       spin_unlock_irqrestore(&quarantine_lock, flags);
+       raw_spin_unlock_irqrestore(&quarantine_lock, flags);
 
        qlist_free_all(&to_free, NULL);
        srcu_read_unlock(&remove_cache_srcu, srcu_idx);
@@ -310,17 +310,17 @@ void quarantine_remove_cache(struct kmem_cache *cache)
         */
        on_each_cpu(per_cpu_remove_cache, cache, 1);
 
-       spin_lock_irqsave(&quarantine_lock, flags);
+       raw_spin_lock_irqsave(&quarantine_lock, flags);
        for (i = 0; i < QUARANTINE_BATCHES; i++) {
                if (qlist_empty(&global_quarantine[i]))
                        continue;
                qlist_move_cache(&global_quarantine[i], &to_free, cache);
                /* Scanning whole quarantine can take a while. */
-               spin_unlock_irqrestore(&quarantine_lock, flags);
+               raw_spin_unlock_irqrestore(&quarantine_lock, flags);
                cond_resched();
-               spin_lock_irqsave(&quarantine_lock, flags);
+               raw_spin_lock_irqsave(&quarantine_lock, flags);
        }
-       spin_unlock_irqrestore(&quarantine_lock, flags);
+       raw_spin_unlock_irqrestore(&quarantine_lock, flags);
 
        qlist_free_all(&to_free, cache);