On Sun, 20 Sep 2009 08:41:40 +0200 Krzysztof Helt <krzysztof.h1@xxxxx> wrote: > From: Krzysztof Helt <krzysztof.h1@xxxxx> > > There is a lockdep warning in the hid_input_report() due to kmalloc(.,GFP_KERNEL) > allocation of a temporary buffer. > Change hid_input_report() call inside the hid_ctrl() after Jiri Slaby's advice. This > converts kmalloc() call into kmalloc(.,GFP_ATOMIC). > > The lockdep trace is: > > WARNING: at kernel/lockdep.c:2457 lockdep_trace_alloc+0xca/0xd0() > Hardware name: Product Name > Modules linked in: usbhid(+) hid uhci_hcd ne2k_pci via_agp 8390 i2c_via > Pid: 0, comm: swapper Not tainted 2.6.31 #74 > Call Trace: > [<c0243b8a>] ? lockdep_trace_alloc+0xca/0xd0 > [<c0221d1c>] warn_slowpath_common+0x7c/0xa0 > [<c0243b8a>] ? lockdep_trace_alloc+0xca/0xd0 > [<c0221d55>] warn_slowpath_null+0x15/0x20 > [<c0243b8a>] lockdep_trace_alloc+0xca/0xd0 > [<c027d2c8>] kmem_cache_alloc+0x28/0x100 > [<cc9359ef>] ? hid_input_report+0x6f/0x220 [hid] > [<cc9359ef>] hid_input_report+0x6f/0x220 [hid] > [<cc94cabf>] hid_ctrl+0x7f/0x180 [usbhid] > [<c03b28b1>] usb_hcd_giveback_urb+0x41/0xa0 > [<cc91a3fc>] uhci_giveback_urb+0x8c/0x280 [uhci_hcd] > [<c0279853>] ? dma_pool_free+0xd3/0x120 > [<cc919848>] ? uhci_free_td+0x58/0xa0 [uhci_hcd] > [<cc91ac01>] uhci_scan_schedule+0x301/0x910 [uhci_hcd] > [<cc91cac4>] uhci_irq+0x94/0x940 [uhci_hcd] > [<c0245c43>] ? __lock_acquire+0x433/0xab0 > [<c0206246>] ? mask_and_ack_8259A+0x66/0x100 > [<c03b494b>] usb_hcd_irq+0x6b/0x90 > [<c0255e7d>] handle_IRQ_event+0x2d/0xc0 > [<c0257e85>] handle_level_irq+0x65/0xe0 > [<c0204c74>] handle_irq+0x34/0x60 > [<c0204bc9>] do_IRQ+0x39/0xb0 > [<c024365c>] ? trace_hardirqs_on_caller+0x12c/0x180 > [<c020328e>] common_interrupt+0x2e/0x40 > [<c0208d48>] ? default_idle+0x38/0x50 > [<c02108df>] apm_cpu_idle+0x10f/0x290 > [<c0201b11>] cpu_idle+0x21/0x40 > [<c045892d>] rest_init+0x4d/0x60 > [<c0575815>] start_kernel+0x235/0x280 > [<c05751f0>] ? unknown_bootoption+0x0/0x210 > [<c057503f>] __init_begin+0x3f/0x50 > In my 2.6.31 tree, kernel/lockdep.c:2457 is in the middle of a #define and the changelog is missing lots of info so I have no hope of understanding what's going on here. > --- > This lockdep is in the current git tree. > > diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c > index 1b0e07a..ab2869d 100644 > --- a/drivers/hid/usbhid/hid-core.c > +++ b/drivers/hid/usbhid/hid-core.c > @@ -455,7 +455,7 @@ static void hid_ctrl(struct urb *urb) > if (usbhid->ctrl[usbhid->ctrltail].dir == USB_DIR_IN) > hid_input_report(urb->context, > usbhid->ctrl[usbhid->ctrltail].report->type, > - urb->transfer_buffer, urb->actual_length, 0); > + urb->transfer_buffer, urb->actual_length, 1); > break; > case -ESHUTDOWN: /* unplug */ > unplug = 1; um, OK, we're clearly inside spinlock here. <starts chasing through the HID code> Why does hid_input_field() use hard-coded GFP_ATOMIC even when interrupt=0? OK, I got down to if (hid->claimed & HID_CLAIMED_HIDDEV && interrupt && hid->hiddev_hid_event) hid->hiddev_hid_event(hid, field, usage, value); in hid_process_event() and gave up. I can't actually find anywhere where the `interrupt' arg to hid_input_report() would cause that code to do something non-atomic when interrupt==0. The code all seems a bit smelly. I don't understand this patch. Can we have a better changelog please? -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
