if TTY config HVC_DRIVER bool help Generic "hypervisor virtual console" infrastructure for various hypervisors (pSeries, iSeries, Xen, lguest). It will automatically be selected if one of the back-end console drivers is selected. config HVC_IRQ bool config HVC_CONSOLE bool "pSeries Hypervisor Virtual Console support" depends on PPC_PSERIES select HVC_DRIVER select HVC_IRQ help pSeries machines when partitioned support a hypervisor virtual console. This driver allows each pSeries partition to have a console which is accessed via the HMC. config HVC_OLD_HVSI bool "Old driver for pSeries serial port (/dev/hvsi*)" depends on HVC_CONSOLE default n config HVC_OPAL bool "OPAL Console support" depends on PPC_POWERNV select HVC_DRIVER select HVC_IRQ default y help PowerNV machines running under OPAL need that driver to get a console config HVC_RTAS bool "IBM RTAS Console support" depends on PPC_RTAS select HVC_DRIVER help IBM Console device driver which makes use of RTAS config HVC_IUCV bool "z/VM IUCV Hypervisor console support (VM only)" depends on S390 select HVC_DRIVER select IUCV default y help This driver provides a Hypervisor console (HVC) back-end to access a Linux (console) terminal via a z/VM IUCV communication path. config HVC_XEN bool "Xen Hypervisor Console support" depends on XEN select HVC_DRIVER select HVC_IRQ default y help Xen virtual console device driver config HVC_XEN_FRONTEND bool "Xen Hypervisor Multiple Consoles support" depends on HVC_XEN select XEN_XENBUS_FRONTEND default y help Xen driver for secondary virtual consoles config HVC_UDBG bool "udbg based fake hypervisor console" depends on PPC select HVC_DRIVER default n help This is meant to be used during HW bring up or debugging when no other console mechanism exist but udbg, to get you a quick console for userspace. Do NOT enable in production kernels. config HVC_DCC bool "ARM JTAG DCC console" depends on ARM || ARM64 select HVC_DRIVER help This console uses the JTAG DCC on ARM to create a console under the HVC driver. This console is used through a JTAG only on ARM. If you don't have a JTAG then you probably don't want this option. config HVC_BFIN_JTAG bool "Blackfin JTAG console" depends on BLACKFIN select HVC_DRIVER help This console uses the Blackfin JTAG to create a console under the the HVC driver. If you don't have JTAG, then you probably don't want this option. config HVCS tristate "IBM Hypervisor Virtual Console Server support" depends on PPC_PSERIES && HVC_CONSOLE help Partitionable IBM Power5 ppc64 machines allow hosting of firmware virtual consoles from one Linux partition by another Linux partition. This driver allows console data from Linux partitions to be accessed through TTY device interfaces in the device tree of a Linux partition running this driver. To compile this driver as a module, choose M here: the module will be called hvcs. Additionally, this module will depend on arch specific APIs exported from hvcserver.ko which will also be compiled when this driver is built as a module. endif # TTY 4e070bc040319aaebfec09e0144dc3341'>rdma/mr_pool.h
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authorDouglas Miller <dougmill@linux.vnet.ibm.com>2017-01-28 06:42:20 -0600
committerTejun Heo <tj@kernel.org>2017-01-28 07:49:42 -0500
commit966d2b04e070bc040319aaebfec09e0144dc3341 (patch)
tree4b96156e3d1dd4dfd6039b7c219c9dc4616da52d /include/rdma/mr_pool.h
parent1b1bc42c1692e9b62756323c675a44cb1a1f9dbd (diff)
percpu-refcount: fix reference leak during percpu-atomic transition
percpu_ref_tryget() and percpu_ref_tryget_live() should return "true" IFF they acquire a reference. But the return value from atomic_long_inc_not_zero() is a long and may have high bits set, e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines is bool so the reference may actually be acquired but the routines return "false" which results in a reference leak since the caller assumes it does not need to do a corresponding percpu_ref_put(). This was seen when performing CPU hotplug during I/O, as hangs in blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start) raced with percpu_ref_tryget (blk_mq_timeout_work). Sample stack trace: __switch_to+0x2c0/0x450 __schedule+0x2f8/0x970 schedule+0x48/0xc0 blk_mq_freeze_queue_wait+0x94/0x120 blk_mq_queue_reinit_work+0xb8/0x180 blk_mq_queue_reinit_prepare+0x84/0xa0 cpuhp_invoke_callback+0x17c/0x600 cpuhp_up_callbacks+0x58/0x150 _cpu_up+0xf0/0x1c0 do_cpu_up+0x120/0x150 cpu_subsys_online+0x64/0xe0 device_online+0xb4/0x120 online_store+0xb4/0xc0 dev_attr_store+0x68/0xa0 sysfs_kf_write+0x80/0xb0 kernfs_fop_write+0x17c/0x250 __vfs_write+0x6c/0x1e0 vfs_write+0xd0/0x270 SyS_write+0x6c/0x110 system_call+0x38/0xe0 Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS, and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests. However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0 and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set. The fix is to make the tryget routines use an actual boolean internally instead of the atomic long result truncated to a int. Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751 Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com> Reviewed-by: Jens Axboe <axboe@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints") Cc: stable@vger.kernel.org # v3.18+
Diffstat (limited to 'include/rdma/mr_pool.h')