Hi, Pawel Laszczak <pawell@xxxxxxxxxxx> writes: >>>>Yet another thread? Can't you just run this right before giving back the >>>>USB request? So, don't do it from IRQ handler, but from giveback path? >>> >>> Do you mean in: >>> if (request->complete) { >>> spin_unlock(&priv_dev->lock); >>> if (priv_dev->run_garbage_collector) { >>> .... >>> } >>> usb_gadget_giveback_request(&priv_ep->endpoint, >>> request); >>> spin_lock(&priv_dev->lock); >>> } >>> ?? >> >>right, you can do it right before giving back the request. Or right >>after. >> >>> I ask because this is finally also called from IRQ handler: >>> >>> cdns3_device_thread_irq_handler >>> -> cdns3_check_ep_interrupt_proceed >>> -> cdns3_transfer_completed >>> -> cdns3_gadget_giveback >>> -> usb_gadget_giveback_request >> >>Did you notice that it doesn't reenable interrupts, though? > > I noticed that there is a lack of reenabling interrupts :) > > The problem is that If I have disabled interrupt the kernel complains > for using dma_free_coherent function in such place. > > Here you have a fragment of complaints: > [ 7420.502863] WARNING: CPU: 0 PID: 10260 at kernel/dma/mapping.c:281 dma_free_attrs+0xa0/0xd0 > [ 7420.502866] Modules linked in: usb_f_mass_storage cdns3(OE) cdns3_pci_wrap(OE) libcomposite > ... > [ 7420.502965] cdns3_gadget_giveback+0x159/0x2a0 [cdns3] > [ 7420.502975] cdns3_transfer_completed+0xc5/0x3c0 [cdns3] > [ 7420.502986] cdns3_device_thread_irq_handler+0x1b1/0xab0 [cdns3] > [ 7420.502991] ? __schedule+0x333/0x7e0 > [ 7420.503001] irq_thread_fn+0x26/0x60 > [ 7420.503006] ? irq_thread+0xa8/0x1b0 > [ 7420.503011] irq_thread+0x10e/0x1b0 > [ 7420.503015] ? irq_forced_thread_fn+0x80/0x80 > [ 7420.503021] ? wake_threads_waitq+0x30/0x30 > [ 7420.503029] kthread+0x12c/0x150 > [ 7420.503034] ? irq_thread_check_affinity+0xe0/0xe0 > [ 7420.503038] ? kthread_park+0x90/0x90 > [ 7420.503045] ret_from_fork+0x3a/0x50 > [ 7420.503061] irq event stamp: 2962 > [ 7420.503065] hardirqs last enabled at (2961): [<ffffffffb252672c>] _raw_spin_unlock_irq+0x2c/0x40 > [ 7420.503070] hardirqs last disabled at (2962): [<ffffffffb25268f5>] _raw_spin_lock_irqsave+0x25/0x60 > [ 7420.503074] softirqs last enabled at (2918): [<ffffffffb2800340>] __do_softirq+0x340/0x451 > [ 7420.503079] softirqs last disabled at (2657): [<ffffffffb1aa02b6>] irq_exit+0xc6/0xd0 > [ 7420.503082] ---[ end trace d02652af11011c3b ]--- > > Maybe it's a bug in implementation of this function. I allocate memory with flag GFP_ATOMIC with > disabled interrupt, but I can't free such memory. I don't understand the intricacies of the coherent API to judge if it's a bug in the API itself. In any case, here's where the splat comes from: void dma_free_attrs(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_handle, unsigned long attrs) { const struct dma_map_ops *ops = get_dma_ops(dev); if (dma_release_from_dev_coherent(dev, get_order(size), cpu_addr)) return; /* * On non-coherent platforms which implement DMA-coherent buffers via * non-cacheable remaps, ops->free() may call vunmap(). Thus getting * this far in IRQ context is a) at risk of a BUG_ON() or trying to * sleep on some machines, and b) an indication that the driver is * probably misusing the coherent API anyway. */ WARN_ON(irqs_disabled()); if (!cpu_addr) return; debug_dma_free_coherent(dev, size, cpu_addr, dma_handle); if (dma_is_direct(ops)) dma_direct_free(dev, size, cpu_addr, dma_handle, attrs); else if (ops->free) ops->free(dev, size, cpu_addr, dma_handle, attrs); } EXPORT_SYMBOL(dma_free_attrs); maybe you're gonna have to fire up a workqueue to free this memory for you :-( Unless someone else has better ideas. Alan, Greg, any ideas? -- balbi
Attachment:
signature.asc
Description: PGP signature