John, On Fri, Oct 16, 2015 at 9:14 PM, John Youn <John.Youn@xxxxxxxxxxxx> wrote: > I reviewed this some more and I think this should be ok. Most of > the handlers don't make sense without a qtd and/or channel. > > Although I am not completely sure on the desc dma case. I think > it will at least be better than letting the use-after-free occur. > > > Acked-by: John Youn <johnyoun@xxxxxxxxxxxx> Thanks! I put some code in to give a stack crawl for the cause of the NULL "qh" case. I'm running with Gregory Herrero's Descriptor DMA series. NULL case only happens if I move "dma_desc_enable" and "dma_desc_fs_enable" away from 0 (right now Rockchip is hardcoded to have dma_desc off). -- kgdb shows: #0 0xc0198728 in arch_kgdb_breakpoint () at arch/arm/include/asm/outercache.h:103 #1 kgdb_breakpoint () at kernel/debug/debug_core.c:1054 #2 0xc0462dcc in dwc2_release_channel_ddma (hsotg=hsotg@entry=0xed426058, qh=qh@entry=0xed682280) at drivers/usb/dwc2/hcd_ddma.c:318 ...AKA on "chan->qh = NULL;" #3 0xc0463f48 in dwc2_hcd_complete_xfer_ddma (hsotg=hsotg@entry=0xed426058, chan=chan@entry=0xed531a40, chnum=chnum@entry=0, halt_status=halt_status@entry=DWC2_HC_XFER_COMPLETE) at drivers/usb/dwc2/hcd_ddma.c:1351 #4 0xc0460414 in dwc2_hc_xfercomp_intr (hsotg=hsotg@entry=0xed426058, chan=chan@entry=0xed531a40, chnum=chnum@entry=0, qtd=qtd@entry=0xed66cc00) at drivers/usb/dwc2/hcd_intr.c:1002 #5 0xc0461814 in dwc2_hc_chhltd_intr_dma (qtd=0xed66cc00, chnum=0, chan=0xed531a40, hsotg=0xed426058) at drivers/usb/dwc2/hcd_intr.c:1830 #6 dwc2_hc_chhltd_intr (qtd=0xed66cc00, chnum=0, chan=0xed531a40, hsotg=0xed426058) at drivers/usb/dwc2/hcd_intr.c:1951 #7 dwc2_hc_n_intr (chnum=0, hsotg=0xed426058) at drivers/usb/dwc2/hcd_intr.c:2063 ...AKA on "dwc2_hc_chhltd_intr(hsotg, chan, chnum, qtd);" #8 dwc2_hc_intr (hsotg=0xed426058) at drivers/usb/dwc2/hcd_intr.c:2138 #9 dwc2_handle_hcd_intr (hsotg=0xed426058) at drivers/usb/dwc2/hcd_intr.c:2188 #10 0xc045c22c in _dwc2_hcd_irq (hcd=<optimized out>) at drivers/usb/dwc2/hcd.c:2895 #11 0xc044752c in usb_hcd_irq (irq=<optimized out>, __hcd=<optimized out>) at drivers/usb/core/hcd.c:2353 -Doug -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html