B1;3202;0cOn Wed, 19 Feb 2014, Dan Williams wrote: > Since commit 77873803363c "net_dma: mark broken" we no longer pin dma > engines active for the network-receive-offload use case. As a result > the ->free_chan_resources() that occurs after the driver self-test no > longer has a NET_DMA induced ->alloc_chan_resources() to back it up. A > late firing irq can lead to ksoftirqd spinning indefinitely due to the > tasklet_disable() performed by ->free_chan_resources(). Only > ->alloc_chan_resources() can clear this condition in affected kernels. > > This problem has been present since commit 3e037454bcfa "I/OAT: Add > support for MSI and MSI-X" in 2.6.24, but is now exposed. Given the > NET_DMA use case is deprecated we can revisit moving the driver to use > threaded irqs. For now, just tear down the irq and tasklet properly by: Right, moving to threaded irqs would get rid of the whole tasklet mess. > 1/ Disable the irq from triggering the tasklet > > 2/ Disable the irq from re-arming > > 3/ Flush inflight interrupts > > 4/ Flush the timer > > 5/ Flush inflight tasklets > > References: > https://lkml.org/lkml/2014/1/27/282 > https://lkml.org/lkml/2014/2/19/672 > > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxx> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> > Reported-by: Mike Galbraith <bitbucket@xxxxxxxxx> > Reported-by: Stanislav Fomichev <stfomichev@xxxxxxxxxxxxxx> > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> As Mike pointed out tsi721_free_chan_resources() has the same issue. I did a quick scan of all tasklet_disable() sites. The teardown or similar wreckage is available in: drivers/atm/he.c drivers/dma/at_hdmac.c drivers/dma/pch_dma.c drivers/input/keyboard/omap-keypad.c drivers/isdn/gigaset/interface.c drivers/media/pci/mantis/mantis_dvb.c drivers/mmc/host/s3cmci.c drivers/net/ethernet/jme.c drivers/net/ethernet/silan/sc92031.c drivers/net/usb/r8152.c drivers/net/wireless/mwl8k.c drivers/ntb/ntb_hw.c drivers/rapidio/devices/tsi721_dma.c drivers/s390/crypto/ap_bus.c drivers/spi/spi-pl022.c drivers/staging/cxt1e1/linux.c drivers/staging/ozwpan/ozhcd.c drivers/usb/gadget/fsl_qe_udc.c That's 18 of 30 usage sites. Impressive.... We need to poke the relevant maintainers to get this solved. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
