summaryrefslogtreecommitdiff
path: root/include/uapi
AgeCommit message (Collapse)AuthorFilesLines
2016-04-29Merge tag 'media/v4.6-4' of ↵Linus Torvalds1-10/+20
git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media Pull media fixes from Mauro Carvalho Chehab: "Some regression fixes: - videobuf2 core: avoid the risk of going past buffer on multi-planes and fix rw mode - fix support for 4K formats at V4L2 core - fix a trouble at davinci_fpe, caused by a bad patch - usbvision: revert a patch with a partial fixup. The fixup patch was merged already, and this one has some issues" * tag 'media/v4.6-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: [media] vb2-memops: Fix over allocation of frame vectors [media] media: vb2: Fix regression on poll() for RW mode [media] v4l2-dv-timings.h: fix polarity for 4k formats [media] davinci_vpfe: Revert "staging: media: davinci_vpfe: remove,unnecessary ret variable" [media] usbvision: revert commit 588afcc1 [media] videobuf2-v4l2: Verify planes array in buffer dequeueing [media] videobuf2-core: Check user space planes array in dqbuf
2016-04-29nfit, libnvdimm: limited/whitelisted dimm command marshaling mechanismDan Williams1-0/+42
There are currently 4 known similar but incompatible definitions of the command sets that can be sent to an NVDIMM through ACPI. It is also clear that future platform generations (ACPI or not) will continue to revise and extend the DIMM command set as new devices and use cases arrive. It is obviously untenable to continue to proliferate divergence of these command definitions, and to that end a standardization process has begun to provide for a unified specification. However, that leaves a problem about what to do with this first generation where vendors are already shipping divergence. The Linux kernel can support these initial diverged platforms without giving platform-firmware free reign to continue to diverge and compound kernel maintenance overhead. The kernel implementation can encourage standardization in two ways: 1/ Require that any function code that userspace wants to send be explicitly white-listed in the implementation. For ACPI this means function codes marked as supported by acpi_check_dsm() may only be invoked if they appear in the white-list. A function must be publicly documented before it is added to the white-list. 2/ The above restrictions can be trivially bypassed by using the "vendor-specific" payload command. However, since vendor-specific commands are by definition not publicly documented and have the potential to corrupt the kernel's view of the dimm state, we provide a toggle to disable vendor-specific operations. Enabling undefined behavior is a policy decision that can be made by the platform owner and encourages firmware implementations to choose public over private command implementations. Based on an initial patch from Jerry Hoemann Cc: Jerry Hoemann <jerry.hoemann@hpe.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-04-28btrfs: uapi/linux/btrfs_tree.h, use __u8 and __u64Jeff Mahoney1-26/+26
u8 and u64 aren't exported to userspace, while __u8 and __u64 are. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2016-04-28btrfs: uapi/linux/btrfs_tree.h migration, item types and definesJeff Mahoney1-0/+966
The BTRFS_IOC_SEARCH_TREE ioctl returns file system items directly to userspace. In order to decode them, full type information is required. Create a new header, btrfs_tree to contain these since most users won't need them. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2016-04-28btrfs: uapi/linux/btrfs.h migration, move struct btrfs_ioctl_defrag_range_argsJeff Mahoney1-1/+37
struct btrfs_ioctl_defrag_range_args is used by the BTRFS_IOC_DEFRAG_RANGE ioctl. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2016-04-28btrfs: uapi/linux/btrfs.h migration, move balance flagsJeff Mahoney1-0/+64
The BTRFS_BALANCE_* flags are used by struct btrfs_ioctl_balance_args.flags and btrfs_ioctl_balance_args.{data,meta,sys}.flags in the BTRFS_IOC_BALANCE ioctl. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2016-04-28btrfs: uapi/linux/btrfs.h migration, move feature flagsJeff Mahoney1-0/+31
The compat/compat_ro/incompat feature flags are used by the feature set/get ioctls. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2016-04-28btrfs: uapi/linux/btrfs.h migration, document subvol flagsJeff Mahoney1-3/+14
Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2016-04-28btrfs: uapi/linux/btrfs.h migration, qgroup limit flagsJeff Mahoney1-1/+21
The BTRFS_QGROUP_LIMIT_* flags are required to tell the kernel which fields are valid when using the BTRFS_IOC_QGROUP_LIMIT ioctl. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2016-04-28btrfs: uapi/linux/btrfs.h migration, move BTRFS_LABEL_SIZEJeff Mahoney1-0/+1
BTRFS_LABEL_SIZE is required to define the BTRFS_IOC_GET_FSLABEL and BTRFS_IOC_SET_FSLABEL ioctls. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2016-04-28btrfs: rename flags for vol args v2David Sterba1-3/+4
Rename BTRFS_DEVICE_BY_ID so it's more descriptive that we specify the device by id, it'll be part of the public API. The mask of supported flags is also renamed, only for internal use. The error code for unknown flags is EOPNOTSUPP, fixed. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2016-04-28btrfs: introduce device delete by devidAnand Jain1-1/+13
This introduces new ioctl BTRFS_IOC_RM_DEV_V2, which uses enhanced struct btrfs_ioctl_vol_args_v2 to carry devid as an user argument. The patch won't delete the old ioctl interface and so kernel remains backward compatible with user land progs. Test case/script: echo "0 $(blockdev --getsz /dev/sdf) linear /dev/sdf 0" | dmsetup create bad_disk mkfs.btrfs -f -d raid1 -m raid1 /dev/sdd /dev/sde /dev/mapper/bad_disk mount /dev/sdd /btrfs dmsetup suspend bad_disk echo "0 $(blockdev --getsz /dev/sdf) error /dev/sdf 0" | dmsetup load bad_disk dmsetup resume bad_disk echo "bad disk failed. now deleting/replacing" btrfs dev del 3 /btrfs echo $? btrfs fi show /btrfs umount /btrfs btrfs-show-super /dev/sdd | egrep num_device dmsetup remove bad_disk wipefs -a /dev/sdf Signed-off-by: Anand Jain <anand.jain@oracle.com> Reported-by: Martin <m_btrfs@ml1.co.uk> [ adjust messages, s/disk/device/ ] Signed-off-by: David Sterba <dsterba@suse.com>
2016-04-28udf: Export superblock magic to userspaceJan Kara1-0/+2
Currently UDF superblock magic doesn't appear in any userspace header files and thus userspace apps have hard time checking for this fs. Let's export the magic to userspace as with any other filesystem. Signed-off-by: Jan Kara <jack@suse.cz>
2016-04-27Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller2-3/+7
Minor overlapping changes in the conflicts. In the macsec case, the change of the default ID macro name overlapped with the 64-bit netlink attribute alignment fixes in net-next. Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-27nl80211: use nla_put_u64_64bit() for the remaining u64 attributesJohannes Berg1-0/+4
Nicolas converted most users, but didn't realize some were generated by macros. Convert those over as well. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2016-04-27drm/sis: add missing include drm.h for the UAPI headerEmil Velikov1-0/+2
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
2016-04-27drm/qxl: remove XXX comment from the UAPI headerEmil Velikov1-1/+0
One cannot rename the struct at this point, so might as well remove the comment. Cc: Gerd Hoffmann <kraxel@redhat.com> Cc: Dave Airlie <airlied@redhat.com> Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
2016-04-27Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds1-2/+2
Pull networking fixes from David Miller: 1) Handle v4/v6 mixed sockets properly in soreuseport, from Craig Gallak. 2) Bug fixes for the new macsec facility (missing kmalloc NULL checks, missing locking around netdev list traversal, etc.) from Sabrina Dubroca. 3) Fix handling of host routes on ifdown in ipv6, from David Ahern. 4) Fix double-fdput in bpf verifier. From Jann Horn. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (31 commits) bpf: fix double-fdput in replace_map_fd_with_map_ptr() net: ipv6: Delete host routes on an ifdown Revert "ipv6: Revert optional address flusing on ifdown." net/mlx4_en: fix spurious timestamping callbacks net: dummy: remove note about being Y by default cxgbi: fix uninitialized flowi6 ipv6: Revert optional address flusing on ifdown. ipv4/fib: don't warn when primary address is missing if in_dev is dead net/mlx5: Add pci shutdown callback net/mlx5_core: Remove static from local variable net/mlx5e: Use vport MTU rather than physical port MTU net/mlx5e: Fix minimum MTU net/mlx5e: Device's mtu field is u16 and not int net/mlx5_core: Add ConnectX-5 to list of supported devices net/mlx5e: Fix MLX5E_100BASE_T define net/mlx5_core: Fix soft lockup in steering error flow qlcnic: Update version to 5.3.64 net: stmmac: socfpga: Remove re-registration of reset controller macsec: fix netlink attribute validation macsec: add missing macsec prefix in uapi ...
2016-04-26sched: align nlattr properly when neededNicolas Dichtel15-0/+16
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-26ovs: align nlattr properly when neededNicolas Dichtel1-0/+2
I also fix commit 8b32ab9e6ef1: use nla_total_size_64bit() for OVS_FLOW_ATTR_USED in ovs_flow_cmd_msg_size(). Fixes: 8b32ab9e6ef1 ("ovs: use nla_put_u64_64bit()") Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-26sock_diag: align nlattr properly when neededNicolas Dichtel1-1/+3
I also fix the value of INET_DIAG_MAX. It's wrong since commit 8f840e47f190 which is only in net-next right now, thus I didn't make a separate patch. Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file") Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-26fs/quota: use nla_put_u64_64bit()Nicolas Dichtel1-0/+1
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-26macsec: use nla_put_u64_64bit()Nicolas Dichtel2-0/+7
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-26Revert "ipv6: Revert optional address flusing on ifdown."David S. Miller1-0/+1
This reverts commit 841645b5f2dfceac69b78fcd0c9050868d41ea61. Ok, this puts the feature back. I've decided to apply David A.'s bug fix and run with that rather than make everyone wait another whole release for this feature. Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-26nl80211: add missing kerneldoc for new *_PAD attributesJohannes Berg1-0/+4
Nicolas's patch missed this, now generating docbook warnings. Add the missing descriptions to address that. Fixes: 2dad624e6dd6 ("wireless: use nla_put_u64_64bit()") Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2016-04-26cfg80211/nl80211: Add support for NL80211_STA_INFO_RX_DURATIONMohammed Shafi Shajakhan1-0/+3
Add support for the a station statistics netlink attribute: NL80211_STA_INFO_RX_DURATION. If present, this attribute contains the aggregate PPDU duration (in microseconds) for all the frames from the peer. This is useful to help understand the total time spent transmitting to us by all of the connected peers. Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2016-04-26ila: add checksum neutral ILA translationsTom Herbert1-0/+7
Support checksum neutral ILA as described in the ILA draft. The low order 16 bits of the identifier are used to contain the checksum adjustment value. The csum-mode parameter is added to described checksum processing. There are three values: - adjust transport checksum (previous behavior) - do checksum neutral mapping - do nothing On output the csum-mode in the ila_params is checked and acted on. If mode is checksum neutral mapping then to mapping and set C-bit. On input, C-bit is checked. If it is set checksum-netural mapping is done (regardless of csum-mode in ila params) and C-bit will be cleared. If it is not set then action in csum-mode is taken. Signed-off-by: Tom Herbert <tom@herbertland.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-25ipv6: Revert optional address flusing on ifdown.David S. Miller1-1/+0
This reverts the following three commits: 70af921db6f8835f4b11c65731116560adb00c14 799977d9aafbf0ca0b9c39b04cbfb16db71302c9 f1705ec197e705b79ea40fe7a2cc5acfa1d3bfac The feature was ill conceived, has terrible semantics, and has added nothing but regressions to the already fragile ipv6 stack. Fixes: f1705ec197e7 ("net: ipv6: Make address flushing on ifdown optional") Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-25wireless: use nla_put_u64_64bit()Nicolas Dichtel1-0/+4
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-25netfilter/ipvs: use nla_put_u64_64bit()Nicolas Dichtel1-0/+1
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-25l2tp: use nla_put_u64_64bit()Nicolas Dichtel1-0/+1
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-25bridge: use nla_put_u64_64bit()Nicolas Dichtel1-0/+2
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-25ovs: use nla_put_u64_64bit()Nicolas Dichtel1-0/+1
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-25ipv6: use nla_put_u64_64bit()Nicolas Dichtel1-0/+1
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-25sched: use nla_put_u64_64bit()Nicolas Dichtel1-0/+3
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-25rtnl: use nla_put_u64_64bit()Nicolas Dichtel1-0/+1
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-25Merge 4.6-rc5 into usb-nextGreg Kroah-Hartman1-0/+121
We want the USB fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-04-25[media] v4l2-dv-timings.h: fix polarity for 4k formatsHans Verkuil1-10/+20
The VSync polarity was negative instead of positive for the 4k CEA formats. I probably copy-and-pasted these from the DMT 4k format, which does have a negative VSync polarity. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Reported-by: Martin Bugge <marbugge@cisco.com> Cc: <stable@vger.kernel.org> # for v4.1 and up Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-04-25[media] videodev2.h: remove 'experimental' annotationsHans Verkuil1-28/+10
Most of what is marked as 'experimental' has been around for years. Time to drop that annotation. The only remaining 'experimental' bits of the API are the debug ioctls and structs: these should remain experimental since the only application that should use this is v4l2-dbg. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-04-25ALSA: timer: remove legacy rtctimerAlexandre Belloni1-1/+1
There are no users of rtctimer left. Remove its code as this is the in-kernel user of the legacy PC RTC driver that will hopefully be removed at some point. Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
2016-04-24macsec: add missing macsec prefix in uapiSabrina Dubroca1-2/+2
I accidentally forgot some MACSEC_ prefixes in if_macsec.h. Fixes: dece8d2b78d1 ("uapi: add MACsec bits") Signed-off-by: Sabrina Dubroca <sd@queasysnail.net> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-24xfrm: align nlattr properly when neededNicolas Dichtel1-0/+1
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-24libnl: nla_put_msecs(): align on a 64-bit areaNicolas Dichtel3-0/+4
nla_data() is now aligned on a 64-bit area. Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-24libnl: nla_put_net64(): align on a 64-bit areaNicolas Dichtel1-0/+1
nla_data() is now aligned on a 64-bit area. The temporary function nla_put_be64_32bit() is removed in this patch. Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-24libnl: nla_put_be64(): align on a 64-bit areaNicolas Dichtel6-0/+16
nla_data() is now aligned on a 64-bit area. A temporary version (nla_put_be64_32bit()) is added for nla_put_net64(). This function is removed in the next patch. Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-24Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-0/+1
Conflicts were two cases of simple overlapping changes, nothing serious. In the UDP case, we need to add a hlist_add_tail_rcu() to linux/rculist.h, because we've moved UDP socket handling away from using nulls lists. Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-24Merge tag 'asm-generic-4.6' of ↵Linus Torvalds1-1/+5
git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic Pull asm-generic update from Arnd Bergmann: "Here is one patch to wire up the preadv/pwritev system calls in the generic system call table, which is required for all architectures that were merged in the last few years, including arm64. Usually these get merged along with the syscall implementation or one of the architecture trees, but this time that did not happen. Andre and Christoph both sent a version of this patch, I picked the one I got first" * tag 'asm-generic-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: generic syscalls: wire up preadv2 and pwritev2 syscalls
2016-04-23generic syscalls: wire up preadv2 and pwritev2 syscallsAndre Przywara1-1/+5
These new syscalls are implemented as generic code, so enable them for architectures like arm64 which use the generic syscall table. Signed-off-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2016-04-23perf/core: Add ::write_backward attribute to perf eventWang Nan1-1/+2
This patch introduces 'write_backward' bit to perf_event_attr, which controls the direction of a ring buffer. After set, the corresponding ring buffer is written from end to beginning. This feature is design to support reading from overwritable ring buffer. Ring buffer can be created by mapping a perf event fd. Kernel puts event records into ring buffer, user tooling like perf fetch them from address returned by mmap(). To prevent racing between kernel and tooling, they communicate to each other through 'head' and 'tail' pointers. Kernel maintains 'head' pointer, points it to the next free area (tail of the last record). Tooling maintains 'tail' pointer, points it to the tail of last consumed record (record has already been fetched). Kernel determines the available space in a ring buffer using these two pointers to avoid overwrite unfetched records. By mapping without 'PROT_WRITE', an overwritable ring buffer is created. Different from normal ring buffer, tooling is unable to maintain 'tail' pointer because writing is forbidden. Therefore, for this type of ring buffers, kernel overwrite old records unconditionally, works like flight recorder. This feature would be useful if reading from overwritable ring buffer were as easy as reading from normal ring buffer. However, there's an obscure problem. The following figure demonstrates a full overwritable ring buffer. In this figure, the 'head' pointer points to the end of last record, and a long record 'E' is pending. For a normal ring buffer, a 'tail' pointer would have pointed to position (X), so kernel knows there's no more space in the ring buffer. However, for an overwritable ring buffer, kernel ignore the 'tail' pointer. (X) head . | . V +------+-------+----------+------+---+ |A....A|B.....B|C........C|D....D| | +------+-------+----------+------+---+ Record 'A' is overwritten by event 'E': head | V +--+---+-------+----------+------+---+ |.E|..A|B.....B|C........C|D....D|E..| +--+---+-------+----------+------+---+ Now tooling decides to read from this ring buffer. However, none of these two natural positions, 'head' and the start of this ring buffer, are pointing to the head of a record. Even the full ring buffer can be accessed by tooling, it is unable to find a position to start decoding. The first attempt tries to solve this problem AFAIK can be found from [1]. It makes kernel to maintain 'tail' pointer: updates it when ring buffer is half full. However, this approach introduces overhead to fast path. Test result shows a 1% overhead [2]. In addition, this method utilizes no more tham 50% records. Another attempt can be found from [3], which allows putting the size of an event at the end of each record. This approach allows tooling to find records in a backward manner from 'head' pointer by reading size of a record from its tail. However, because of alignment requirement, it needs 8 bytes to record the size of a record, which is a huge waste. Its performance is also not good, because more data need to be written. This approach also introduces some extra branch instructions to fast path. 'write_backward' is a better solution to this problem. Following figure demonstrates the state of the overwritable ring buffer when 'write_backward' is set before overwriting: head | V +---+------+----------+-------+------+ | |D....D|C........C|B.....B|A....A| +---+------+----------+-------+------+ and after overwriting: head | V +---+------+----------+-------+---+--+ |..E|D....D|C........C|B.....B|A..|E.| +---+------+----------+-------+---+--+ In each situation, 'head' points to the beginning of the newest record. From this record, tooling can iterate over the full ring buffer and fetch records one by one. The only limitation that needs to be considered is back-to-back reading. Due to the non-deterministic of user programs, it is impossible to ensure the ring buffer keeps stable during reading. Consider an extreme situation: tooling is scheduled out after reading record 'D', then a burst of events come, eat up the whole ring buffer (one or multiple rounds). When the tooling process comes back, reading after 'D' is incorrect now. To prevent this problem, we need to find a way to ensure the ring buffer is stable during reading. ioctl(PERF_EVENT_IOC_PAUSE_OUTPUT) is suggested because its overhead is lower than ioctl(PERF_EVENT_IOC_ENABLE). By carefully verifying 'header' pointer, reader can avoid pausing the ring-buffer. For example: /* A union of all possible events */ union perf_event event; p = head = perf_mmap__read_head(); while (true) { /* copy header of next event */ fetch(&event.header, p, sizeof(event.header)); /* read 'head' pointer */ head = perf_mmap__read_head(); /* check overwritten: is the header good? */ if (!verify(sizeof(event.header), p, head)) break; /* copy the whole event */ fetch(&event, p, event.header.size); /* read 'head' pointer again */ head = perf_mmap__read_head(); /* is the whole event good? */ if (!verify(event.header.size, p, head)) break; p += event.header.size; } However, the overhead is high because: a) In-place decoding is not safe. Copying-verifying-decoding is required. b) Fetching 'head' pointer requires additional synchronization. (From Alexei Starovoitov: Even when this trick works, pause is needed for more than stability of reading. When we collect the events into overwrite buffer we're waiting for some other trigger (like all cpu utilization spike or just one cpu running and all others are idle) and when it happens the buffer has valuable info from the past. At this point new events are no longer interesting and buffer should be paused, events read and unpaused until next trigger comes.) This patch utilizes event's default overflow_handler introduced previously. perf_event_output_backward() is created as the default overflow handler for backward ring buffers. To avoid extra overhead to fast path, original perf_event_output() becomes __perf_event_output() and marked '__always_inline'. In theory, there's no extra overhead introduced to fast path. Performance testing: Calling 3000000 times of 'close(-1)', use gettimeofday() to check duration. Use 'perf record -o /dev/null -e raw_syscalls:*' to capture system calls. In ns. Testing environment: CPU : Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz Kernel : v4.5.0 MEAN STDVAR BASE 800214.950 2853.083 PRE1 2253846.700 9997.014 PRE2 2257495.540 8516.293 POST 2250896.100 8933.921 Where 'BASE' is pure performance without capturing. 'PRE1' is test result of pure 'v4.5.0' kernel. 'PRE2' is test result before this patch. 'POST' is test result after this patch. See [4] for the detailed experimental setup. Considering the stdvar, this patch doesn't introduce performance overhead to the fast path. [1] http://lkml.iu.edu/hypermail/linux/kernel/1304.1/04584.html [2] http://lkml.iu.edu/hypermail/linux/kernel/1307.1/00535.html [3] http://lkml.iu.edu/hypermail/linux/kernel/1512.0/01265.html [4] http://lkml.kernel.org/g/56F89DCD.1040202@huawei.com Signed-off-by: Wang Nan <wangnan0@huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Cc: <acme@kernel.org> Cc: <pi3orama@163.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Cc: He Kuang <hekuang@huawei.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: Zefan Li <lizefan@huawei.com> Link: http://lkml.kernel.org/r/1459865478-53413-1-git-send-email-wangnan0@huawei.com [ Fixed the changelog some more. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22Merge tag 'v4.6-rc3' into drm-nextDave Airlie2-1/+3
Backmerge 4.6-rc3 for i915. Linux 4.6-rc3