Date: Mon, 21 Nov 2005 10:36:07 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: rashmi ns <nsrashmi@gmail.com>, bugi@lists.redbrick.dcu.ie Subject: Re: Driver crashes after unloading a module Message-ID: <200511211036.08460.jhb@freebsd.org> In-Reply-To: <9f9993160511200804w177a521s9cddc6e56afe221e@mail.gmail.com> References: <9f9993160511200804w177a521s9cddc6e56afe221e@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sunday 20 November 2005 11:04 am, rashmi ns wrote:
> Hello List ,
>
> Thanks for the help you given me .
>
> We have written driver for hdlc controller .The kernel is crashing
> after unloading
> the module with trap 12 fault .here is the order in which we release the
> resources while detaching the device.
>
> 1. stop polling timer(if polling mode)
>
> 2. destroy_dev()
>
> 3. disable the device
>
> 4. free Tx and Rx structures
>
> 5. deallocate allocated dma memory
>
> 6. bus_deactivate_resource(irq)
>
> 7. release all bus resources
>
> here is the piece of code
>
> /*release bus resources*/
>
> static void hdlc_release(struct hdlc_softc *sc)
>
> {
>
> dbgprint("Entering");
>
> bus_generic_detach(sc->dev);
>
> /*Release the resources held*/
>
> if (sc->irq){
>
> bus_teardown_intr(sc->dev, sc->irq,sc->int_handler_tag);
>
> sc->int_handler_tag = NULL;
>
> bus_release_resource(sc->dev, SYS_RES_IRQ,sc->irq_rid, sc->irq);
>
> dbgprint("deallocated irq res irq_rid = %d\n",sc->irq_rid);
>
> }
>
> if (sc->mem){
>
> bus_release_resource (sc->dev, SYS_RES_MEMORY, sc->mem_rid, sc->mem);
>
> dbgprint("deallocated bus res\n");
>
> }
>
> if(&sc->sc_mtx)
>
> mtx_destroy(&sc->sc_mtx);
>
> }
As a first guess, do this later since you might still get an open request up
until your call to destroy_dev(). Also, you might need to create a purge
routine your devsw if threads can block in your devsw routines and wakeup any
sleepers in your purge handler so that when destroy-dev() returns you know
that all threads are out of your driver.
> /*detach function*/
>
> static int hdlc_detach(device_t dev)
>
> {
>
> struct hdlc_softc *sc = device_get_softc(dev);
>
> int s;
>
> dbgprint("Entering\n");
>
> s=splimp();
>
> /*If drv is in poll mode then stop the poll timer */
>
> if(sc->intr_mode == 0)
>
> hdlc_clear_poll_mode(sc);
>
> if(!(sc->hdlc_cdev == NULL) ){
>
> destroy_dev(sc->hdlc_cdev);
>
> }
>
> /*stop the controller */
>
> hdlc_hw_reset(sc);
>
> /*free hdlc Tx and Rx structures */
>
> hdlc_stop(sc);
>
> /*deallocate allocated dma memory*/
>
> hdlc_free_descriptors(sc);
>
> bus_deactivate_resource(sc->dev,SYS_RES_IRQ,sc->irq_rid,sc->irq);
>
> splx(s);
>
> /*free bus resources*/
>
> hdlc_release(sc);
>
> uprintf("Detached\n");
>
> return 0;
>
> }
>
> After unloading the module the it gives the debug print "Module
> unloaded" kld_loader function from and kernel crashes with trap 12 .Kindly
> let me know does the order of releasing the resources is the reason for
> this.
>
> Thanks and regards,
>
> Rashmi.n.s
> _______________________________________________
> freebsd-hackers@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
> To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
--
John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve" = http://www.FreeBSD.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200511211036.08460.jhb>