[bug report] ALSA: mixart: Use nonatomic PCM ops

[bug report] ALSA: mixart: Use nonatomic PCM ops

[Dan Carpenter]

[ This bug predates git but my email script just uses `git blame -w`.
  -dan ]

Hello Takashi Iwai,

The patch 8d3a8b5cb57d: "ALSA: mixart: Use nonatomic PCM ops" from
Sep 10, 2014, leads to the following static checker warning:

	sound/pci/mixart/mixart_core.c:73 get_msg()
	warn: called with lock held.  '&mgr->msg_lock'

sound/pci/mixart/mixart_core.c
    63  static int get_msg(struct mixart_mgr *mgr, struct mixart_msg *resp,
    64                     u32 msg_frame_address )
    65  {
    66          u32  headptr;
    67          u32  size;
    68          int  err;
    69  #ifndef __BIG_ENDIAN
    70          unsigned int i;
    71  #endif
    72  
    73          mutex_lock(&mgr->msg_lock);
                ^^^^^^^^^^^^^^^^^^^^^^^^^^
Smatch says that get_msg() is called with this lock already held.

    74          err = 0;
    75  
    76          /* copy message descriptor from miXart to driver */
    77          size                =  readl_be(MIXART_MEM(mgr, msg_frame_address));       /* size of descriptor + response */
    78          resp->message_id    =  readl_be(MIXART_MEM(mgr, msg_frame_address + 4));   /* dwMessageID */


[ snip ]

   419  irqreturn_t snd_mixart_threaded_irq(int irq, void *dev_id)
   420  {
   421          struct mixart_mgr *mgr = dev_id;
   422          int err;
   423          struct mixart_msg resp;
   424          u32 msg;
   425  
   426          mutex_lock(&mgr->lock);
                ^^^^^^^^^^^^^^^^^^^^^^
We are holding the lock

   427          /* process interrupt */
   428          while (retrieve_msg_frame(mgr, &msg)) {
   429  
   430                  switch (msg & MSG_TYPE_MASK) {
   431                  case MSG_TYPE_COMMAND:
   432                          resp.message_id = 0;
   433                          resp.data = mixart_msg_data;
   434                          resp.size = sizeof(mixart_msg_data);
   435                          err = get_msg(mgr, &resp, msg & ~MSG_TYPE_MASK);
                                      ^^^^^^^^^^^
When get_msg() is called on this path.

   436                          if( err < 0 ) {
   437                                  dev_err(&mgr->pci->dev,
   438                                          "interrupt: error(%d) reading mf %x\n",
   439                                          err, msg);
   440                                  break;
   441                          }
   442  
   443                          if(resp.message_id == MSG_SERVICES_TIMER_NOTIFY) {

regards,
dan carpenter