ALSA: ctxfi - Fix Oops at mmapping

Replace a spinlock with a mutex protecting the vm block list at
mmap / munmap calls, which caused Oops like below:

BUG: sleeping function called from invalid context at mm/slub.c:1599
in_atomic(): 0, irqs_disabled(): 1, pid: 32065, name: xine
Pid: 32065, comm: xine Tainted: P           2.6.29.4-75.fc10.x86_64 #1
Call Trace:
  [<ffffffff81040685>] __might_sleep+0x105/0x10a
  [<ffffffff810c9fae>] kmem_cache_alloc+0x32/0xe2
  [<ffffffffa08e3110>] ct_vm_map+0xfa/0x19e [snd_ctxfi]
  [<ffffffffa08e1a07>] ct_map_audio_buffer+0x4c/0x76 [snd_ctxfi]
  [<ffffffffa08e2aa5>] atc_pcm_playback_prepare+0x1d7/0x2a8 [snd_ctxfi]
  [<ffffffff8105ef3f>] ? up_read+0x9/0xb
  [<ffffffff81186b61>] ? __up_read+0x7c/0x87
  [<ffffffffa08e36a6>] ct_pcm_playback_prepare+0x39/0x60 [snd_ctxfi]
  [<ffffffffa0886bcb>] snd_pcm_do_prepare+0x16/0x28 [snd_pcm]
  [<ffffffffa08867c7>] snd_pcm_action_single+0x2d/0x5b [snd_pcm]
  [<ffffffffa08881f3>] snd_pcm_action_nonatomic+0x52/0x6a [snd_pcm]
  [<ffffffffa088a723>] snd_pcm_common_ioctl1+0x404/0xc79 [snd_pcm]
  [<ffffffff810c52c8>] ? alloc_pages_current+0xb9/0xc2
  [<ffffffff810c9402>] ? new_slab+0x1a5/0x1cb
  [<ffffffff810ab9ea>] ? vma_prio_tree_insert+0x23/0xc1
  [<ffffffffa088b411>] snd_pcm_playback_ioctl1+0x213/0x230 [snd_pcm]
  [<ffffffff810b6c20>] ? mmap_region+0x397/0x4c9
  [<ffffffffa088bd9b>] snd_pcm_playback_ioctl+0x2e/0x36 [snd_pcm]
  [<ffffffff810ddc64>] vfs_ioctl+0x2a/0x78
  [<ffffffff810de130>] do_vfs_ioctl+0x462/0x4a2
  [<ffffffff81029cef>] ? default_spin_lock_flags+0x9/0xe
  [<ffffffff81374647>] ? trace_hardirqs_off_thunk+0x3a/0x6c
  [<ffffffff810de1c5>] sys_ioctl+0x55/0x77
  [<ffffffff8101133a>] system_call_fastpath+0x16/0x1b

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 11 insertions, 3 deletions

diff --git a/sound/pci/ctxfi/ctvmem.c b/sound/pci/ctxfi/ctvmem.c
index cecf77e3ee86..363b67e3a9e7 100644
--- a/sound/pci/ctxfi/ctvmem.c
+++ b/sound/pci/ctxfi/ctvmem.c
@@ -35,25 +35,27 @@ get_vm_block(struct ct_vm *vm, unsigned int size)
         struct ct_vm_block *block = NULL, *entry = NULL;
         struct list_head *pos = NULL;
 
+        mutex_lock(&vm->lock);
         list_for_each(pos, &vm->unused) {
                 entry = list_entry(pos, struct ct_vm_block, list);
                 if (entry->size >= size)
                         break; /* found a block that is big enough */
         }
         if (pos == &vm->unused)
-                return NULL;
+                goto out;
 
         if (entry->size == size) {
                 /* Move the vm node from unused list to used list directly */
                 list_del(&entry->list);
                 list_add(&entry->list, &vm->used);
                 vm->size -= size;
-                return entry;
+                block = entry;
+                goto out;
         }
 
         block = kzalloc(sizeof(*block), GFP_KERNEL);
         if (NULL == block)
-                return NULL;
+                goto out;
 
         block->addr = entry->addr;
         block->size = size;
@@ -62,6 +64,8 @@ get_vm_block(struct ct_vm *vm, unsigned int size)
         entry->size -= size;
         vm->size -= size;
 
+ out:
+        mutex_unlock(&vm->lock);
         return block;
 }
 
@@ -70,6 +74,7 @@ static void put_vm_block(struct ct_vm *vm, struct ct_vm_block *block)
         struct ct_vm_block *entry = NULL, *pre_ent = NULL;
         struct list_head *pos = NULL, *pre = NULL;
 
+        mutex_lock(&vm->lock);
         list_del(&block->list);
         vm->size += block->size;
 
@@ -106,6 +111,7 @@ static void put_vm_block(struct ct_vm *vm, struct ct_vm_block *block)
                 pos = pre;
                 pre = pos->prev;
         }
+        mutex_unlock(&vm->lock);
 }
 
 /* Map host addr (kmalloced/vmalloced) to device logical addr. */
@@ -191,6 +197,8 @@ int ct_vm_create(struct ct_vm **rvm)
         if (NULL == vm)
                 return -ENOMEM;
 
+        mutex_init(&vm->lock);
+
         /* Allocate page table pages */
         for (i = 0; i < CT_PTP_NUM; i++) {
                 vm->ptp[i] = kmalloc(PAGE_SIZE, GFP_KERNEL);