config NFSD tristate "NFS server support" depends on INET depends on FILE_LOCKING select LOCKD select SUNRPC select EXPORTFS select NFS_ACL_SUPPORT if NFSD_V2_ACL depends on MULTIUSER help Choose Y here if you want to allow other computers to access files residing on this system using Sun's Network File System protocol. To compile the NFS server support as a module, choose M here: the module will be called nfsd. You may choose to use a user-space NFS server instead, in which case you can choose N here. To export local file systems using NFS, you also need to install user space programs which can be found in the Linux nfs-utils package, available from http://linux-nfs.org/. More detail about the Linux NFS server implementation is available via the exports(5) man page. Below you can choose which versions of the NFS protocol are available to clients mounting the NFS server on this system. Support for NFS version 2 (RFC 1094) is always available when CONFIG_NFSD is selected. If unsure, say N. config NFSD_V2_ACL bool depends on NFSD config NFSD_V3 bool "NFS server support for NFS version 3" depends on NFSD help This option enables support in your system's NFS server for version 3 of the NFS protocol (RFC 1813). If unsure, say Y. config NFSD_V3_ACL bool "NFS server support for the NFSv3 ACL protocol extension" depends on NFSD_V3 select NFSD_V2_ACL help Solaris NFS servers support an auxiliary NFSv3 ACL protocol that never became an official part of the NFS version 3 protocol. This protocol extension allows applications on NFS clients to manipulate POSIX Access Control Lists on files residing on NFS servers. NFS servers enforce POSIX ACLs on local files whether this protocol is available or not. This option enables support in your system's NFS server for the NFSv3 ACL protocol extension allowing NFS clients to manipulate POSIX ACLs on files exported by your system's NFS server. NFS clients which support the Solaris NFSv3 ACL protocol can then access and modify ACLs on your NFS server. To store ACLs on your NFS server, you also need to enable ACL- related CONFIG options for your local file systems of choice. If unsure, say N. config NFSD_V4 bool "NFS server support for NFS version 4" depends on NFSD && PROC_FS select NFSD_V3 select FS_POSIX_ACL select SUNRPC_GSS select CRYPTO select GRACE_PERIOD help This option enables support in your system's NFS server for version 4 of the NFS protocol (RFC 3530). To export files using NFSv4, you need to install additional user space programs which can be found in the Linux nfs-utils package, available from http://linux-nfs.org/. If unsure, say N. config NFSD_PNFS bool config NFSD_BLOCKLAYOUT bool "NFSv4.1 server support for pNFS block layouts" depends on NFSD_V4 && BLOCK select NFSD_PNFS select EXPORTFS_BLOCK_OPS help This option enables support for the exporting pNFS block layouts in the kernel's NFS server. The pNFS block layout enables NFS clients to directly perform I/O to block devices accesible to both the server and the clients. See RFC 5663 for more details. If unsure, say N. config NFSD_SCSILAYOUT bool "NFSv4.1 server support for pNFS SCSI layouts" depends on NFSD_V4 && BLOCK select NFSD_PNFS select EXPORTFS_BLOCK_OPS help This option enables support for the exporting pNFS SCSI layouts in the kernel's NFS server. The pNFS SCSI layout enables NFS clients to directly perform I/O to SCSI devices accesible to both the server and the clients. See draft-ietf-nfsv4-scsi-layout for more details. If unsure, say N. config NFSD_FLEXFILELAYOUT bool "NFSv4.1 server support for pNFS Flex File layouts" depends on NFSD_V4 select NFSD_PNFS help This option enables support for the exporting pNFS Flex File layouts in the kernel's NFS server. The pNFS Flex File layout enables NFS clients to directly perform I/O to NFSv3 devices accesible to both the server and the clients. See draft-ietf-nfsv4-flex-files for more details. Warning, this server implements the bare minimum functionality to be a flex file server - it is for testing the client, not for use in production. If unsure, say N. config NFSD_V4_SECURITY_LABEL bool "Provide Security Label support for NFSv4 server" depends on NFSD_V4 && SECURITY help Say Y here if you want enable fine-grained security label attribute support for NFS version 4. Security labels allow security modules like SELinux and Smack to label files to facilitate enforcement of their policies. Without this an NFSv4 mount will have the same label on each file. If you do not wish to enable fine-grained security labels SELinux or Smack policies on NFSv4 files, say N. config NFSD_FAULT_INJECTION bool "NFS server manual fault injection" depends on NFSD_V4 && DEBUG_KERNEL && DEBUG_FS help This option enables support for manually injecting faults into the NFS server. This is intended to be used for testing error recovery on the NFS client. If unsure, say N. nfo'> 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 /drivers/usb/serial/omninet.c 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 'drivers/usb/serial/omninet.c')