splat atomic:64-bit: Create thread outside spin lock

The Fedora 3.6 debug kernel identified the following issue where
we create a thread under a spin lock.  This isn't safe because
sleeping could result in a deadlock.  Therefore the lock is changed
to a mutex so it's safe to sleep.

  BUG: sleeping function called from invalid context at mm/slub.c:930
  in_atomic(): 1, irqs_disabled(): 0, pid: 10583, name: splat
  1 lock held by splat/10583:

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

diff --git a/module/splat/splat-atomic.c b/module/splat/splat-atomic.c
index cdb3353f9cddaae2622d3aa30b2714a06c515402..efb01578adc02ef59fb55f1e708f59ab8b16af29 100644 (file)
--- a/module/splat/splat-atomic.c
+++ b/module/splat/splat-atomic.c
@@ -51,7 +51,7 @@ typedef enum {
 typedef struct atomic_priv {
         unsigned long ap_magic;
         struct file *ap_file;
-       spinlock_t ap_lock;
+       struct mutex ap_lock;
         wait_queue_head_t ap_waitq;
        volatile uint64_t ap_atomic;
        volatile uint64_t ap_atomic_exited;
@@ -69,10 +69,10 @@ splat_atomic_work(void *priv)
        ap = (atomic_priv_t *)priv;
        ASSERT(ap->ap_magic == SPLAT_ATOMIC_TEST_MAGIC);
 
-       spin_lock(&ap->ap_lock);
+       mutex_lock(&ap->ap_lock);
        op = ap->ap_op;
        wake_up(&ap->ap_waitq);
-       spin_unlock(&ap->ap_lock);
+       mutex_unlock(&ap->ap_lock);
 
         splat_vprint(ap->ap_file, SPLAT_ATOMIC_TEST1_NAME,
                     "Thread %d successfully started: %lu/%lu\n", op,
@@ -142,13 +142,13 @@ splat_atomic_test1(struct file *file, void *arg)
 
        ap.ap_magic = SPLAT_ATOMIC_TEST_MAGIC;
        ap.ap_file = file;
-       spin_lock_init(&ap.ap_lock);
+       mutex_init(&ap.ap_lock);
        init_waitqueue_head(&ap.ap_waitq);
        ap.ap_atomic = SPLAT_ATOMIC_INIT_VALUE;
        ap.ap_atomic_exited = 0;
 
        for (i = 0; i < SPLAT_ATOMIC_COUNT_64; i++) {
-               spin_lock(&ap.ap_lock);
+               mutex_lock(&ap.ap_lock);
                ap.ap_op = i;
 
                thr = (kthread_t *)thread_create(NULL, 0, splat_atomic_work,
@@ -156,14 +156,14 @@ splat_atomic_test1(struct file *file, void *arg)
                                                 minclsyspri);
                if (thr == NULL) {
                        rc = -ESRCH;
-                       spin_unlock(&ap.ap_lock);
+                       mutex_unlock(&ap.ap_lock);
                        break;
                }
 
                /* Prepare to wait, the new thread will wake us once it
                 * has made a copy of the unique private passed data */
                 prepare_to_wait(&ap.ap_waitq, &wait, TASK_UNINTERRUPTIBLE);
-               spin_unlock(&ap.ap_lock);
+               mutex_unlock(&ap.ap_lock);
                schedule();
        }