Messages in this thread | | | Date | Thu, 20 Mar 2003 12:47:01 +0100 | From | Maarten Ghijsen <> | Subject | wake_up call from IRQ handler freezes system (no Oops) |
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Hello,
I am designing a linux driver for a DVB/ASI PCI card.
One of the IOCTL commands implemented in my driver allows the user to transfer a buffer to the PCI card (using DMA). While the DMA is in progress I want to sleep the user process/thread. For the sleeping I use the wait_event function, which waits for an event that is 'fired' from the DMA done interrupt (with wake_up call). As soon as the interrupt handler calls the wake_up my system freezes completely, without any Oops or other exception message.
As far as I can gather from the linux device driver book and other sources from drivers it is common practice to use a wake_up in the interrupt routine to awaken any sleeping user threads. I am pretty sure that I have initialised my wait_queue_head_t correctly with a call to init_waitqueue_head.
Does anyone have any idea why the system hangs on the wake-up from the interrupt handler?
Below you will find some pseudo code for with the wait_event and the wake_up:
// wait from DMA IOCTL handler void Dta1xxTxIoCtlDma() { startdma();
wait_event(my_wait_queue, ( 1==dma_done_flag) );
return; }
// wake_up from interrupt handler void Dta1xxIRQ() { if ( IsDmaDoneInterruptSet() ) { dma_done_flag = 1; wake_up(&my_wait_queue); } }
I am using linux kernel version 2.4.18.
Regards, Maarten
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