From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pz0-f51.google.com ([209.85.210.51]:45199 "EHLO mail-pz0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752454Ab2DWN4D (ORCPT ); Mon, 23 Apr 2012 09:56:03 -0400 From: Jiang Liu To: Vinod Koul , Dan Williams Cc: Jiang Liu , Keping Chen , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v1 0/8] enhance dmaengine core to support DMA device hotplug Date: Mon, 23 Apr 2012 21:51:41 +0800 Message-Id: <1335189109-4871-1-git-send-email-jiang.liu@huawei.com> Sender: linux-pci-owner@vger.kernel.org List-ID: From: Jiang Liu This patchset tries to enhance the dmaengine and its clients to support hot-removal of DMA devices at runtime, especially for IOAT devices. When hot-removing IOH (PCI host bridge) on Intel Nehalem/Westmere platform, we need to remove all IOAT devices embedded in the IOH. For future Intel processor with IIO (Embedded IOH), we need to remove IOAT devices even when hot-removing a physical processor. But current dmaengine implementation doesn't support hot-removal of IOAT devices at runtime. Currently dmaengine has an assumption that a DMA device could only be deregistered when there's no any clients making use of the dmaengine. So dma_async_device_unregister() is designed to be called by DMA driver's exit routines only. But the ioatdma driver doesn't conform to that design, it calls dma_async_device_unregister() from dma_async_device_unregister(), which is called in the driver detaching path. Following simple test could unveil the issue. The proposed solution is to get rid of the assumption and enhance dma_async_device_unregister(), so it could be called from DMA driver's detach routines. It will also introduce several interfaces and enhance dmaengine clients to support hot-removal of DMA devices at runtime. This patchset applies to the mainline kernel at cdd5983 Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost --------------------------------------------------------------------- echo 0000:80:16.7 > /sys/bus/pci/drivers/ioatdma/unbind ioatdma 0000:80:16.7: Removing dma and dca services ------------[ cut here ]------------ WARNING: at drivers/dma/dmaengine.c:831 dma_async_device_unregister+0xd5/0xf0() (Tainted: G ---------------- T) Hardware name: System x3850 X5 -[7143O3G]- dma_async_device_unregister called while 17 clients hold a reference Modules linked in: ebtable_nat ebtables ipt_MASQUERADE iptable_nat nf_nat xt_CHECKSUM iptable_mangle bridge stp llc autofs4 sunrpc cpufreq_ondemand acpi_cpufreq freq_table mperf ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4 iptable_filter ip_tables ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables ipv6 vfat fat vhost_net macvtap macvlan tun kvm_intel kvm uinput microcode sg serio_raw cdc_ether usbnet mii be2net i2c_i801 i2c_core iTCO_wdt iTCO_vendor_support shpchp i7core_edac edac_core ioatdma igb dca e1000e bnx2 ext4 mbcache jbd2 sr_mod cdrom sd_mod crc_t10dif qla2xxx pmcraid pata_acpi ata_generic ata_piix bfa(T) scsi_transport_fc scsi_tgt megaraid_sas dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_wait_scan] Pid: 5143, comm: bash Tainted: G ---------------- T 2.6.32-220.el6.x86_64 #1 Call Trace: [] ? warn_slowpath_common+0x87/0xc0 [] ? warn_slowpath_fmt+0x46/0x50 [] ? dma_async_device_unregister+0xd5/0xf0 [] ? ioat_dma_remove+0x28/0x4a [ioatdma] [] ? ioat_remove+0x82/0x8a [ioatdma] [] ? pci_device_remove+0x37/0x70 [] ? __device_release_driver+0x6f/0xe0 [] ? device_release_driver+0x2d/0x40 [] ? driver_unbind+0xa1/0xc0 [] ? drv_attr_store+0x2c/0x30 [] ? sysfs_write_file+0xe5/0x170 [] ? vfs_write+0xb8/0x1a0 [] ? audit_syscall_entry+0x272/0x2a0 [] ? sys_write+0x51/0x90 [] ? system_call_fastpath+0x16/0x1b ---[ end trace 436e184dbc830d94 ]--- ioatdma 0000:80:16.7: dma_pool_destroy dma_desc_pool, ffff881073536000 busy ioatdma 0000:80:16.7: dma_pool_destroy dma_desc_pool, ffff881073533000 busy ioatdma 0000:80:16.7: dma_pool_destroy dma_desc_pool, ffff88107352f000 busy ioatdma 0000:80:16.7: dma_pool_destroy dma_desc_pool, ffff88107352c000 busy ioatdma 0000:80:16.7: dma_pool_destroy dma_desc_pool, ffff881073529000 busy ioatdma 0000:80:16.7: dma_pool_destroy completion_pool, ffff881073527000 busy --------------------------------------------------------------------- Jiang Liu (8): dmaengine: enhance DMA channel reference count management dmaengine: rebalance DMA channels when CPU hotplug happens dmaengine: introduce CONFIG_DMA_ENGINE_HOTPLUG for DMA device hotplug dmaengine: use atomic_t for struct dma_chan->client_count field dmaengine: enhance dma_async_device_unregister() to be called by drv->remove() dmaengine: enhance network subsystem to support DMA device hotplug dmaengine: enhance ASYNC_TX subsystem to support DMA device hotplug dmaengine: assign DMA channel to CPU according to NUMA affinity crypto/async_tx/async_memcpy.c | 2 + crypto/async_tx/async_memset.c | 2 + crypto/async_tx/async_pq.c | 10 +- crypto/async_tx/async_raid6_recov.c | 8 +- crypto/async_tx/async_tx.c | 6 +- crypto/async_tx/async_xor.c | 13 +- drivers/dma/Kconfig | 6 + drivers/dma/dmaengine.c | 384 ++++++++++++++++++++++------------- include/linux/async_tx.h | 13 ++ include/linux/dmaengine.h | 30 +++ include/net/netdma.h | 26 +++ net/ipv4/tcp.c | 10 +- net/ipv4/tcp_input.c | 5 +- net/ipv4/tcp_ipv4.c | 4 +- net/ipv6/tcp_ipv6.c | 4 +- 15 files changed, 357 insertions(+), 166 deletions(-) -- 1.7.5.4