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It's racy, creating mmap offsets is a slowpath, so better to remove it
to avoid drivers doing broken things.
The only user is i915, and it's ok there because everything (well
almost) is protected by dev->struct_mutex in i915-gem.
While at it add a note in the create_mmap_offset kerneldoc that
drivers must release it again. And then I also noticed that
drm_gem_object_release entirely lacks kerneldoc.
Cc: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-14-git-send-email-daniel.vetter@ffwll.ch
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When extracting the value at full precision (16 bits), no need to
round the value.
This was spotted by Jani when running sparse. Unfortunately this fix
doesn't get rid of the warning.
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reported-by: Jani Nikula <jani.nikula@intel.com>
Cc: Daniel Stone <daniels@collabora.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: dri-devel@lists.freedesktop.org
Fixes: 5488dc16fde7 ("drm: introduce pipe color correction properties")
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1458655833-19547-1-git-send-email-lionel.g.landwerlin@intel.com
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The CCP has the ability to provide DMA services to the
kernel using pass-through mode of the device. Register
these services as general purpose DMA channels.
Changes since v2:
- Add a Signed-off-by
Changes since v1:
- Allocate memory for a string in ccp_dmaengine_register
- Ensure register/unregister calls are properly ordered
- Verified all changed files are listed in the diffstat
- Undo some superfluous changes
- Added a cc:
Signed-off-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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The R-Car SYSC PM Domain driver has to power manage devices in power
areas using clocks. To reuse code and to share knowledge of clocks
suitable for power management, this is ideally done through the existing
cpg_mssr_attach_dev() and cpg_mssr_detach_dev() callbacks.
Hence these callbacks can no longer rely on their "domain" parameter
pointing to the CPG/MSSR Clock Domain. To handle this, keep a pointer to
the clock domain in a static variable. cpg_mssr_attach_dev() has to
support probe deferral, as the R-Car SYSC PM Domain may be initialized,
and devices may be added to it, before the CPG/MSSR Clock Domain is
initialized.
Dummy callbacks are provided for the case where CPG/MSTP support is not
included, so the rcar-sysc driver won't have to care about this.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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Provide dummy cpg_mstp_{at,de}tach_dev() PM Domain callbacks if CPG/MSTP
support is not included, so the rcar-sysc driver won't have to care
about this.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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By passing the smd channel reference to the callback, rather than the
smd device, we can open additional smd channels from sub-devices of smd
devices.
Also updates the two smd clients today found in mainline.
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
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When using LVS-NAT and SIP persistence-egine over UDP, the following
limitations are present with current implementation:
1) To actually have load-balancing based on Call-ID header, you need to
use one-packet-scheduling mode. But with one-packet-scheduling the
connection is deleted just after packet is forwarded, so SIP responses
coming from real-servers do not match any connection and SNAT is
not applied.
2) If you do not use "-o" option, IPVS behaves as normal UDP load
balancer, so different SIP calls (each one identified by a different
Call-ID) coming from the same ip-address/port go to the same
real-server. So basically you don’t have load-balancing based on
Call-ID as intended.
3) Call-ID is not learned when a new SIP call is started by a real-server
(inside-to-outside direction), but only in the outside-to-inside
direction. This would be a general problem for all SIP servers acting
as Back2BackUserAgent.
This patch aims to solve problems 1) and 3) while keeping OPS mode
mandatory for SIP-UDP, so that 2) is not a problem anymore.
The basic mechanism implemented is to make packets, that do not match any
existent connection but come from real-servers, create new connections
instead of let them pass without any effect.
When such packets pass through ip_vs_out(), if their source ip address and
source port match a configured real-server, a new connection is
automatically created in the same way as it would have happened if the
packet had come from outside-to-inside direction. A new connection template
is created too if the virtual-service is persistent and there is no
matching connection template found. The new connection automatically
created, if the service had "-o" option, is an OPS connection that lasts
only the time to forward the packet, just like it happens on the
ingress side.
The main part of this mechanism is implemented inside a persistent-engine
specific callback (at the moment only SIP persistent engine exists) and
is triggered only for UDP packets, since connection oriented protocols, by
using different set of ports (typically ephemeral ports) to open new
outgoing connections, should not need this feature.
The following requisites are needed for automatic connection creation; if
any is missing the packet simply goes the same way as before.
a) virtual-service is not fwmark based (this is because fwmark services
do not store address and port of the virtual-service, required to
build the connection data).
b) virtual-service and real-servers must not have been configured with
omitted port (this is again to have all data to create the connection).
Signed-off-by: Marco Angaroni <marcoangaroni@gmail.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
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This patch adds a new helper for cls/act programs that can push events
to user space applications. For networking, this can be f.e. for sampling,
debugging, logging purposes or pushing of arbitrary wake-up events. The
idea is similar to a43eec304259 ("bpf: introduce bpf_perf_event_output()
helper") and 39111695b1b8 ("samples: bpf: add bpf_perf_event_output example").
The eBPF program utilizes a perf event array map that user space populates
with fds from perf_event_open(), the eBPF program calls into the helper
f.e. as skb_event_output(skb, &my_map, BPF_F_CURRENT_CPU, raw, sizeof(raw))
so that the raw data is pushed into the fd f.e. at the map index of the
current CPU.
User space can poll/mmap/etc on this and has a data channel for receiving
events that can be post-processed. The nice thing is that since the eBPF
program and user space application making use of it are tightly coupled,
they can define their own arbitrary raw data format and what/when they
want to push.
While f.e. packet headers could be one part of the meta data that is being
pushed, this is not a substitute for things like packet sockets as whole
packet is not being pushed and push is only done in a single direction.
Intention is more of a generically usable, efficient event pipe to applications.
Workflow is that tc can pin the map and applications can attach themselves
e.g. after cls/act setup to one or multiple map slots, demuxing is done by
the eBPF program.
Adding this facility is with minimal effort, it reuses the helper
introduced in a43eec304259 ("bpf: introduce bpf_perf_event_output() helper")
and we get its functionality for free by overloading its BPF_FUNC_ identifier
for cls/act programs, ctx is currently unused, but will be made use of in
future. Example will be added to iproute2's BPF example files.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add a BPF_F_CURRENT_CPU flag to optimize the use-case where user space has
per-CPU ring buffers and the eBPF program pushes the data into the current
CPU's ring buffer which saves us an extra helper function call in eBPF.
Also, make sure to properly reserve the remaining flags which are not used.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Struct ctl_table_header holds pointer to sysctl table which could be used
for freeing it after unregistration. IPv4 sysctls already use that.
Remove redundant NULL assignment: ndev allocated using kzalloc.
This also saves some bytes: sysctl table could be shorter than
DEVCONF_MAX+1 if some options are disable in config.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
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skb->sk could point to timewait or request socket which has no sk_classid.
Detected as "BUG: KASAN: slab-out-of-bounds in cls_cgroup_classify".
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add registration APIs in the clk fixed-rate code to return struct
clk_hw pointers instead of struct clk pointers. This way we hide
the struct clk pointer from providers unless they need to use
consumer facing APIs.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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Add registration APIs in the clk gpio code to return struct
clk_hw pointers instead of struct clk pointers. This way we hide
the struct clk pointer from providers unless they need to use
consumer facing APIs.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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Add registration APIs in the clk composite code to return struct
clk_hw pointers instead of struct clk pointers. This way we hide
the struct clk pointer from providers unless they need to use
consumer facing APIs.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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Add registration APIs in the clk fractional divider code to
return struct clk_hw pointers instead of struct clk pointers.
This way we hide the struct clk pointer from providers unless
they need to use consumer facing APIs.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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Add registration APIs in the clk fixed-factor code to return
struct clk_hw pointers instead of struct clk pointers. This way
we hide the struct clk pointer from providers unless they need to
use consumer facing APIs.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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Add registration APIs in the clk mux code to return struct clk_hw
pointers instead of struct clk pointers. This way we hide the
struct clk pointer from providers unless they need to use
consumer facing APIs.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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Add registration APIs in the clk gate code to return struct
clk_hw pointers instead of struct clk pointers. This way we hide
the struct clk pointer from providers unless they need to use
consumer facing APIs.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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Add registration APIs in the clk divider code to return struct
clk_hw pointers instead of struct clk pointers. This way we hide
the struct clk pointer from providers unless they need to use
consumer facing APIs.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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Now that we have a clk registration API that doesn't return
struct clks, we need to have some way to hand out struct clks via
the clk_get() APIs that doesn't involve associating struct clk
pointers with a struct clk_lookup. Luckily, clkdev already
operates on struct clk_hw pointers, except for the registration
facing APIs where it converts struct clk pointers into struct
clk_hw pointers almost immediately.
Let's add clk_hw based registration APIs so that we can skip the
conversion step and provide a way for clk provider drivers to
operate exclusively on clk_hw structs. This way we clearly
split the API between consumers and providers.
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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Now that we have a clk registration API that doesn't return
struct clks, we need to have some way to hand out struct clks via
the clk_get() APIs that doesn't involve associating struct clk
pointers with an OF node. Currently we ask the OF provider to
give us a struct clk pointer for some clkspec, turn that struct
clk into a struct clk_hw and then allocate a new struct clk to
return to the caller.
Let's add a clk_hw based OF provider hook that returns a struct
clk_hw directly, so that we skip the intermediate step of
converting from struct clk to struct clk_hw. Eventually when
we've converted all OF clk providers to struct clk_hw based APIs
we can remove the struct clk based ones.
It should also be noted that we change the onecell provider to
have a flex array instead of a pointer for the array of clk_hw
pointers. This allows providers to allocate one structure of the
correct length in one step instead of two.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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We've largely split the clk consumer and provider APIs along
struct clk and struct clk_hw, but clk_register() still returns a
struct clk pointer for each struct clk_hw that's registered.
Eventually we'd like to only allocate struct clks when there's a
user, because struct clk is per-user now, so clk_register() needs
to change.
Let's add new APIs to register struct clk_hws, but this time
we'll hide the struct clk from the caller by returning an int
error code. Also add an unregistration API that takes the clk_hw
structure that was passed to the registration API. This way
provider drivers never have to deal with a struct clk pointer
unless they're using the clk consumer APIs.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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Now that we've converted the only caller over to another clkdev
API, remove this one.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Suggested-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Merge the ptmx internal interface cleanup branch.
This doesn't change semantics, but it should be a sane basis for
eventually getting the multi-instance devpts code into some sane shape
where we can get rid of the kernel config option. Which we can
hopefully get done next merge window..
* ptmx-cleanup:
devpts: clean up interface to pty drivers
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The original thought was that if a device implemented ACS, then surely
we want to use that... well, it turns out that devices can make an ACS
capability so broken that we still need to fall back to quirks.
Reverse the order of ACS enabling to give quirks first shot at it.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
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Add IIC clocks to r8a7794 device tree.
Based on similar work for the r8a7790 by Wolfram Sang.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
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Add CAN nodes to r8a7794 device tree.
Based on work by Sergei Shtylyov for the r8a7791 SoC.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
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Based on Rev. 2.00 of the R-Car Gen2 datasheet.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
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Similar to enable_event/disable_event triggers, these triggers enable
and disable the aggregation of events into maps rather than enabling
and disabling their writing into the trace buffer.
They can be used to automatically start and stop hist triggers based
on a matching filter condition.
If there's a paused hist trigger on system:event, the following would
start it when the filter condition was hit:
# echo enable_hist:system:event [ if filter] > event/trigger
And the following would disable a running system:event hist trigger:
# echo disable_hist:system:event [ if filter] > event/trigger
See Documentation/trace/events.txt for real examples.
Link: http://lkml.kernel.org/r/f812f086e52c8b7c8ad5443487375e03c96a601f.1457029949.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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This helper function can be used to copy the arguments of a
phandle to an array.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Rob Herring <robh@kernel.org>
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With this macro any user can easily iterate over a list of
phandles. The patch also converts __of_parse_phandle_with_args()
to make use of the macro.
The of_count_phandle_with_args() function is not converted,
because the macro hides the return value of of_phandle_iterator_init(),
which is needed in there.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Rob Herring <robh@kernel.org>
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Move the code to walk over the phandles out of the loop in
__of_parse_phandle_with_args() to a separate function that
just works with the iterator handle: of_phandle_iterator_next().
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Rob Herring <robh@kernel.org>
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This struct carrys all necessary information to iterate over
a list of phandles and extract the arguments. Add an
init-function for the iterator and make use of it in
__of_parse_phandle_with_args().
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Rob Herring <robh@kernel.org>
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Replace the default nand_ecclayout definitions for large and small page
devices with the equivalent mtd_ooblayout_ops.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
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ECC layout definitions are currently exposed using the nand_ecclayout
struct which embeds oobfree and eccpos arrays with predefined size.
This approach was acceptable when NAND chips were providing relatively
small OOB regions, but MLC and TLC now provide OOB regions of several
hundreds of bytes, which implies a non negligible overhead for everybody
even those who only need to support legacy NANDs.
Create an mtd_ooblayout_ops interface providing the same functionality
(expose the ECC and oobfree layout) without the need for this huge
structure.
The mtd->ecclayout is now deprecated and should be replaced by the
equivalent mtd_ooblayout_ops. In the meantime we provide a wrapper around
the ->ecclayout field to ease migration to this new model.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
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Add an mtd_set_ecclayout() helper function to avoid direct accesses to the
mtd->ecclayout field. This will ease future reworks of ECC layout
definition.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
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In order to make the ecclayout definition completely dynamic we need to
rework the way the OOB layout are defined and iterated.
Create a few mtd_ooblayout_xxx() helpers to ease OOB bytes manipulation
and hide ecclayout internals to their users.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
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Export the default read/write oob functions (for the standard and syndrome
scheme), so that drivers can use them for their raw implementation and
implement their own functions for the normal oob operation.
This is required if your ECC engine is capable of fixing some of the OOB
data. In this case you have to overload the ->read_oob() and ->write_oob(),
but if you don't specify the ->read/write_oob_raw() functions they are
assigned to the ->read/write_oob() implementation, which is not what you
want.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
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The new IFC controller version 2.0 has a different memory map page.
Upto IFC 1.4 PAGE size is 4 KB and from IFC2.0 PAGE size is 64KB.
This patch segregates the IFC global and runtime registers to appropriate
PAGE sizes.
Signed-off-by: Jaiprakash Singh <b44839@freescale.com>
Signed-off-by: Raghav Dogra <raghav@freescale.com>
Acked-by: Li Yang <leoyang.li@nxp.com>
Signed-off-by: Raghav Dogra <raghav.dogra@nxp.com>
Acked-by: Scott Wood <oss@buserror.net>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
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NAND subsystem is being slightly reworked to store ECC details in
separated fields. In future we'll want to add support for more DT
properties as specifying every possible setup with a single
"nand-ecc-mode" is a pretty bad idea.
To allow this let's add a helper that will support something like
"nand-ecc-algo" in future. Right now we use it for keeping backward
compatibility.
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
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Our nand_ecc_modes_t is already a bit abused by value NAND_ECC_SOFT_BCH.
This enum should store ECC mode only and putting algorithm details there
is a bad idea. It would result in too many values impossible to support
in a sane way.
To solve this problem let's add a new enum. We'll have to modify all
drivers to set it properly but once it's done it'll be possible to drop
NAND_ECC_SOFT_BCH. That will result in a cleaner design and more
possibilities like setting ECC algorithm for hardware ECC mode.
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds into nand/next
Pull leds-trigger changes from Jacek Anaszewski.
Create a generic mtd led-trigger to replace the exisitng nand led-trigger
implementation.
* 'mtd-nand-trigger' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds:
mtd: Hook I/O activity to the MTD LED trigger
mtd: nand: Remove the "nand-disk" LED trigger
leds: trigger: Introduce a MTD (NAND/NOR) trigger
mtd: Uninline mtd_write_oob and move it to mtdcore.c
leds: trigger: Introduce a kernel panic LED trigger
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Some of kernel driver uses the IIO framework to get the sensor
value via ADC or IIO HW driver. The client driver get iio channel
by iio_channel_get_all() and release it by calling
iio_channel_release_all().
Add resource managed version (devm_*) of these APIs so that if client
calls the devm_iio_channel_get_all() then it need not to release it
explicitly, it can be done by managed device framework when driver
get un-binded.
This reduces the code in error path and also need of .remove callback in
some cases.
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
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Some of kernel driver uses the IIO framework to get the sensor
value via ADC or IIO HW driver. The client driver get iio channel
by iio_channel_get() and release it by calling iio_channel_release().
Add resource managed version (devm_*) of these APIs so that if client
calls the devm_iio_channel_get() then it need not to release it explicitly,
it can be done by managed device framework when driver get un-binded.
This reduces the code in error path and also need of .remove callback in
some cases.
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
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Some types of ST Sensors can be connected to the same IRQ line
as other peripherals using open drain. Add a device tree binding
and a sensor data property to flip the right bit in the interrupt
control register to enable open drain mode on the INT line.
If the line is set to be open drain, also tag on IRQF_SHARED
to the IRQ flags when requesting the interrupt, as the whole
point of using open drain interrupt lines is to share them with
more than one peripheral (wire-or).
Cc: devicetree@vger.kernel.org
Cc: Giuseppe Barba <giuseppe.barba@st.com>
Cc: Denis Ciocca <denis.ciocca@st.com>
Acked-by: Rob Herring <rob@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
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This makes all ST sensor drivers check that they actually have
new data available for the requested channel(s) before claiming
an IRQ, by reading the status register (which is conveniently
the same for all ST sensors) and check that the channel has new
data before proceeding to read it and fill the buffer.
This way sensors can share an interrupt line: it can be flaged
as shared and then the sensor that did not fire will return
NO_IRQ, and the sensor that fired will handle the IRQ and
return IRQ_HANDLED.
Cc: Giuseppe Barba <giuseppe.barba@st.com>
Cc: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
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Since the nlattr header is 4 bytes in size, it can cause the netlink
attribute payload to not be 8-byte aligned.
This is particularly troublesome for IFLA_STATS64 which contains 64-bit
statistic values.
Solve this by creating a dummy IFLA_PAD attribute which has a payload
which is zero bytes in size. When HAVE_EFFICIENT_UNALIGNED_ACCESS is
false, we insert an IFLA_PAD attribute into the netlink response when
necessary such that the IFLA_STATS64 payload will be properly aligned.
With help and suggestions from Eric Dumazet.
Signed-off-by: David S. Miller <davem@davemloft.net>
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'hist' triggers allow users to continually aggregate trace events,
which can then be viewed afterwards by simply reading a 'hist' file
containing the aggregation in a human-readable format.
The basic idea is very simple and boils down to a mechanism whereby
trace events, rather than being exhaustively dumped in raw form and
viewed directly, are automatically 'compressed' into meaningful tables
completely defined by the user.
This is done strictly via single-line command-line commands and
without the aid of any kind of programming language or interpreter.
A surprising number of typical use cases can be accomplished by users
via this simple mechanism. In fact, a large number of the tasks that
users typically do using the more complicated script-based tracing
tools, at least during the initial stages of an investigation, can be
accomplished by simply specifying a set of keys and values to be used
in the creation of a hash table.
The Linux kernel trace event subsystem happens to provide an extensive
list of keys and values ready-made for such a purpose in the form of
the event format files associated with each trace event. By simply
consulting the format file for field names of interest and by plugging
them into the hist trigger command, users can create an endless number
of useful aggregations to help with investigating various properties
of the system. See Documentation/trace/events.txt for examples.
hist triggers are implemented on top of the existing event trigger
infrastructure, and as such are consistent with the existing triggers
from a user's perspective as well.
The basic syntax follows the existing trigger syntax. Users start an
aggregation by writing a 'hist' trigger to the event of interest's
trigger file:
# echo hist:keys=xxx [ if filter] > event/trigger
Once a hist trigger has been set up, by default it continually
aggregates every matching event into a hash table using the event key
and a value field named 'hitcount'.
To view the aggregation at any point in time, simply read the 'hist'
file in the same directory as the 'trigger' file:
# cat event/hist
The detailed syntax provides additional options for user control, and
is described exhaustively in Documentation/trace/events.txt and in the
virtual tracing/README file in the tracing subsystem.
Link: http://lkml.kernel.org/r/72d263b5e1853fe9c314953b65833c3aa75479f2.1457029949.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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