take into account possibility of comedi_poll getting called from

interrupt context (kcomedilib).  Removed some dead code.  Fix
tiny possibility of undetected buffer overrun.  Added a memory
barrier to ni_sync_ai_dma().

diff --git a/comedi/drivers/ni_mio_common.c b/comedi/drivers/ni_mio_common.c
index bf415a010ba37276cb383e73f0ef4b30288439bd..acca249818b826b7920f7222c9ecd8c6446dd552 100644 (file)
--- a/comedi/drivers/ni_mio_common.c
+++ b/comedi/drivers/ni_mio_common.c
@@ -409,10 +409,12 @@ static void ni_sync_ai_dma(struct mite_struct *mite, comedi_device *dev)
        comedi_buf_write_alloc(s->async, s->async->prealloc_bufsz);
 
        nbytes = mite_bytes_transferred(mite, AI_DMA_CHAN);
-       /* XXX should use mite_bytes_read() for the overrun check
-        * since mite_bytes_transferred returns a conservative
-        * lower bound */
-       if( (int)(nbytes - old_alloc_count) > 0 ){
+       rmb();
+       /* We use mite_bytes_read() for the overrun check
+        * because it returns an upper board, and mite_bytes_transferred
+        * returns a lower bound on the number of bytes actually
+        * transferred */
+       if( (int)(mite_bytes_read(mite, AI_DMA_CHAN) - old_alloc_count) > 0 ){
                printk("ni_mio_common: DMA overwrite of free area\n");
                ni_ai_reset(dev,s);
                async->events |= COMEDI_CB_OVERFLOW;
@@ -420,12 +422,12 @@ static void ni_sync_ai_dma(struct mite_struct *mite, comedi_device *dev)
        }
 
        count = nbytes - async->buf_write_count;
-       if( count < 0 ){
+       if( count <= 0 ){
                /* it's possible count will be negative due to
                 * conservative value returned by mite_bytes_transferred */
                return;
        }
-
+       mb();
        comedi_buf_write_free(async, count);
 
        async->scan_progress += count;
@@ -471,57 +473,6 @@ static void mite_handle_b_linkc(struct mite_struct *mite, comedi_device *dev)
        async->events |= COMEDI_CB_BLOCK;
 }
 
-#if 0
-static void mite_handle_interrupt(comedi_device *dev,unsigned int m_status)
-{
-       int len;
-       comedi_subdevice *s = dev->subdevices+0;
-       comedi_async *async = s->async;
-       struct mite_struct *mite = devpriv->mite;
-
-       async->events |= COMEDI_CB_BLOCK;
-
-       MDPRINTK("mite_handle_interrupt: m_status=%08x\n",m_status);
-       if(m_status & CHSR_DONE){
-               writel(CHOR_CLRDONE, mite->mite_io_addr + MITE_CHOR(0));
-       }
-
-#if 0
-       len = sizeof(sampl_t)*async->cmd.stop_arg*async->cmd.scan_end_arg;
-       if((devpriv->mite->DMA_CheckNearEnd) &&
-                       (s->async->buf_int_count > (len - s->async->prealloc_bufsz))) {
-               long offset;
-               int i;
-
-               offset = len % async->prealloc_bufsz;
-               if(offset < mite->ring[0].count) {
-                       mite->ring[0].count = offset;
-                       mite->ring[1].count = 0;
-               }else{
-                       offset -= mite->ring[0].count;
-                       i = offset >> PAGE_SHIFT;
-                       mite->ring[i].count = offset & ~PAGE_MASK;
-                       mite->ring[(i+1)%mite->n_links].count = 0;
-               }
-               mite->DMA_CheckNearEnd = 0;
-       }
-#endif
-
-#if  0
-       MDPRINTK("CHSR is 0x%08x, count is %d\n",m_status,async->buf_int_count);
-       if(m_status&CHSR_DONE){
-               writel(CHOR_CLRDONE, mite->mite_io_addr + MITE_CHOR(mite->chan));
-               //printk("buf_int_count is %d, buf_int_ptr is %d\n",
-               //              s->async->buf_int_count,s->async->buf_int_ptr);
-               ni_handle_block_dma(dev);
-       }
-       MDPRINTK("exit mite_handle_interrupt\n");
-#endif
-
-       //comedi_event(dev,s,async->events);
-}
-#endif
-
 static int ni_ao_wait_for_dma_load( comedi_device *dev )
 {
        static const int timeout = 10000;
@@ -1180,14 +1131,16 @@ static int ni_ai_poll(comedi_device *dev,comedi_subdevice *s)
        int count;
 
        // lock to avoid race with interrupt handler
-       comedi_spin_lock_irqsave(&dev->spinlock, flags);
+       if(in_interrupt() == 0)
+               comedi_spin_lock_irqsave(&dev->spinlock, flags);
 #ifndef PCIDMA
        ni_handle_fifo_dregs(dev);
 #else
        ni_sync_ai_dma(devpriv->mite, dev);
 #endif
        count = s->async->buf_write_count - s->async->buf_read_count;
-       comedi_spin_unlock_irqrestore(&dev->spinlock, flags);
+       if(in_interrupt() == 0)
+               comedi_spin_unlock_irqrestore(&dev->spinlock, flags);
 
        return count;
 }