With the addition of uAPSD and driver buffering
the powersave handling has gotten quite complex.
Add a section to the documentation to explain it
for anyone wanting to implement it.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
iwlwifi has a separate EOSP notification from
the device, and to make use of that properly
it needs to be passed to mac80211. To be able
to mix with tx_status_irqsafe and rx_irqsafe
it also needs to be an "_irqsafe" version in
the sense that it goes through the tasklet,
the actual flag clearing would be IRQ-safe
but doing it directly would cause reordering
issues.
This is needed in the case of a P2P GO going
into an absence period without transmitting
any frames that should be driver-released as
in this case there's no other way to inform
mac80211 that the service period ended. Note
that for drivers that don't use the _irqsafe
functions another version of this function
will be required.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
iwlwifi needs to know the number of frames that are
going to be sent to a station while it is asleep so
it can properly handle the uCode blocking of that
station.
Before uAPSD, we got by by telling the device that
a single frame was going to be released whenever we
encountered IEEE80211_TX_CTL_POLL_RESPONSE. With
uAPSD, however, that is no longer possible since
there could be more than a single frame.
To support this model, add a new callback to notify
drivers when frames are going to be released.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
If a PS-poll frame is retried (but was received)
there is no way to detect that since it has no
sequence number. As a consequence, the standard
asks us to not react to PS-poll frames until the
response to one made it out (was ACKed or lost).
Implement this by using the WLAN_STA_SP flags to
also indicate a PS-Poll "service period" and the
IEEE80211_TX_STATUS_EOSP flag for the response
packet to indicate the end of the "SP" as usual.
We could use separate flags, but that will most
likely completely confuse drivers, and while the
standard doesn't exclude simultaneously polling
using uAPSD and PS-Poll, doing that seems quite
problematic.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Add uAPSD support to mac80211. This is probably not
possible with all devices, so advertising it with
the cfg80211 flag will be left up to drivers that
want it.
Due to my previous patches it is now a fairly
straight-forward extension. Drivers need to have
accurate TX status reporting for the EOSP frame.
For drivers that buffer themselves, the provided
APIs allow releasing the right number of frames,
but then drivers need to set EOSP and more-data
themselves. This is documented in more detail in
the new code itself.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
If there are frames for a station buffered in
the driver, mac80211 announces those in the TIM
IE but there's no way to release them. Add new
API to release such frames and use it when the
station polls for a frame.
Since the API will soon also be used for uAPSD
it is easily extensible.
Note that before this change drivers announcing
driver-buffered frames in the TIM bit actually
will respond to a PS-Poll with a potentially
lower priority frame (if there are any frames
buffered in mac80211), after this patch a driver
that hasn't been changed will no longer respond
at all. This only affects ath9k, which will need
to be fixed to implement the new API.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
For uAPSD support we'll need to have per-AC PS
buffers. As this is a major undertaking, split
the buffers before really adding support for
uAPSD. This already makes some reference to the
uapsd_queues variable, but for now that will
never be non-zero.
Since book-keeping is complicated, also change
the logic for keeping a maximum of frames only
and allow 64 frames per AC (up from 128 for a
station).
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
For uAPSD implementation, it is necessary to know on
which ACs frames are buffered. mac80211 obviously
knows about the frames it has buffered itself, but
with aggregation many drivers buffer frames. Thus,
mac80211 needs to be informed about this.
For now, since we don't have APSD in any form, this
will unconditionally set the TIM bit for the station
but later with uAPSD only some ACs might cause the
TIM bit to be set.
ath9k is the only driver using this API and I only
modify it in the most basic way, it won't be able
to implement uAPSD with this yet. But it can't do
that anyway since there's no way to selectively
release frames to the peer yet.
Since drivers will buffer frames per TID, let them
inform mac80211 on a per TID basis, mac80211 will
then sort out the AC mapping itself.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
When adding a TDLS peer STA, mark it with a new flag in both nl80211 and
mac80211. Before adding a peer, make sure the wiphy supports TDLS and
our operating mode is appropriate (managed).
In addition, make sure all peers are removed on disassociation.
A TDLS peer is first added just before link setup is initiated. In later
setup stages we have more info about peer supported rates, capabilities,
etc. This info is reported via nl80211_set_station().
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Cc: Kalyan C Gaddam <chakkal@iit.edu>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Register and implement the TDLS cfg80211 callback functions.
Internally prepare and send TDLS management frames. We incorporate
local STA capabilities and supported rates with extra IEs given by
usermode. The resulting packet is either encapsulated in a data frame,
or assembled as an action frame. It is transmitted either directly or
through the AP, as mandated by the TDLS specification.
Declare support for the TDLS external setup wiphy capability. This
tells usermode to handle link setup and discovery on its own, and use the
kernel driver for sending TDLS mgmt packets.
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Cc: Kalyan C Gaddam <chakkal@iit.edu>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Relocate the mesh implementation of adding the (extended) supported
rates IE to util.c, anticipating its use by other parts of mac80211.
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Cc: Kalyan C Gaddam <chakkal@iit.edu>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Add support for sending high-level TDLS commands and TDLS frames via
NL80211_CMD_TDLS_OPER and NL80211_CMD_TDLS_MGMT, respectively. Add
appropriate cfg80211 callbacks for lower level drivers.
Add wiphy capability flags for TDLS support and advertise them via
nl80211.
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Cc: Kalyan C Gaddam <chakkal@iit.edu>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Currently, when hostapd sets the station as authorized
we also overwrite its uAPSD parameter. This obviously
leads to buggy behaviour (later, with my patches that
actually add uAPSD support). To fix this, only apply
those parameters if they were actually set in nl80211,
and to achieve that add a bitmap of things to apply.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Make report_iommu_fault() return -ENOSYS whenever an iommu fault
handler isn't installed, so IOMMU drivers can then do their own
platform-specific default behavior if they wanted.
Fault handlers can still return -ENOSYS in case they want to elicit the
default behavior of the IOMMU drivers.
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
overlay_info struct, used to configure overlays, currently includes both
physical and virtual addresses for the pixels. The vaddr was added to
support more exotic configurations where CPU would be used to update a
display, but it is not currently used and there has been no interest in
the feature. Using CPU to update a screen is also less interesting now
that OMAP4 has two LCD outputs.
This patch removes the vaddr field, and modifies the users of omapdss
accordingly. This makes the use of omapdss a bit simpler, as the user
doesn't need to think if it needs to give the vaddr.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
This is a driver for N800's display, ported from the old omapfb. This is
a slightly lighter version of the driver as not all features of the old
driver can be ported without big changes to DSS2, and also because some
of the HW features used in the old driver are unclear (e.g. the power
management part).
That said, the new driver works fine for basic use.
Architecturally the driver is not as neat as it could be. N800's display
HW consists of a display buffer chip and a panel, and ideally they would
be represented by separate, independent drivers. This is not currently
possible, and this driver contains both buffer chip and panel driver.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Taal panel driver supports two kinds of backlight control: 1) using DSI
commands sent to the panel to control the backlight, 2) calling function
pointers going to the board file to control the backlight.
The second option is a bit hacky, and will no longer be needed when the
PWM driver supports the backlight features. After that we can use the
standard PWM backlight driver.
This patch removes the second backlight control mechanism, and adds a
boolean field, use_dsi_backlight, to nokia_dsi_panel_data which the
board file can use to inform whether the panel driver should use DSI
commands to control the backlight.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
We have currently panel-generic-dpi driver, which is a combined driver
for dummy panels and also for DVI output.
The aim is to split the panel-generic-dpi into two, one for fixed size
dummy panels connected via DPI, and the other (this) for variable
resolution output which supports DDC channel (in practice a DVI framer
chip connected to DPI output).
Original i2c code by: Ricardo Salveti de Araujo
<ricardo.salveti@canonical.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
regn divider is currently programmed to the registers without change,
but when calculating clock frequencies it is used as regn+1.
To make this similar to how DSI handles the dividers this patch changes
the regn value to be used as such for calculations, but the value
programmed to registers is regn-1.
This simplifies the clock frequency calculations, makes it similar to
DSI, and also allows us to use regn value 0 as undefined.
Cc: Mythri P K <mythripk@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Add initial support for DSI video mode panels:
- Add a new structure omap_dss_dsi_videomode_data in the member "panel" in
omap_dss_device struct. This allows panel driver to configure dsi video_mode
specific parameters.
- Configure basic DSI video mode timing parameters: HBP, HFP, HSA, VBP, VFP, VSA,
TL and VACT.
- Configure DSI protocol engine registers for video_mode support.
- Introduce functions dsi_video_mode_enable() and dsi_video_mode_disable() which
enable/disable video mode for a given virtual channel and a given pixel format
type.
Things left for later
- Add functions to check for errors in video mode timings provided by panel.
- Configure timing registers required for command mode interleaving.
Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Currently, DSI pixel info is only represented by the pixel size in bits using
the pixel_size parameter in omap_dss_device struct's ctrl member.
This is not sufficient information for DSI video mode usage, as two of the
supported formats(RGB666 loosely packed, and RGB888) have the same pixel
container size, but different data_type values for the video mode packet header.
Create enum "omap_dss_dsi_pixel_format" which describes the pixel data format
the panel is configured for. Create helper function dsi_get_pixel_size() which
returns the pixel size of the given pixel format.
Modify functions omapdss_default_get_recommended_bpp() and dss_use_replication()
to use dsi_get_pixel_size().
Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Introduce read functions which use generic Processor-to-Peripheral
transaction types. These are needed by some devices which may not support
corresponding DCS commands.
Add function dsi_vc_generic_send_read_request() which can send
a short packet with 0, 1 or 2 bytes of request data and the corresponding
generic data type.
Rename function dsi_vc_dcs_read_rx_fifo() to dsi_vc_read_rx_fifo() and modify
it to take the enum "dss_dsi_content_type" as an argument to use either DCS
or GENERIC Peripheral-to-Processor transaction types while parsing data read
from the device.
Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Remove functions dsi_vc_dcs_read_1() and dsi_vc_dcs_read_2(), these are used
when the panel is expected to return 1 and 2 bytes respecitvely. This was manily
used for debugging purposes. These functions should be implemented in the panel
driver if needed.
Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Intoduce enum "dss_dsi_content_type" to differentiate between DCS and generic
content types.
Introduce short and long packet write functions which use generic
Processor-to-Peripheral transaction types. These are needed by some devices
which may not support corresponding DCS commands. Create common write functions
which allow code reuse between DCS and generic write functions.
Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Create an enum for DSI operation modes, use this to set the capabilities of the
device in dsi_init_display().
Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Add OMAP_DSS_OVL_CAP_GLOBAL_ALPHA and OMAP_DSS_OVL_CAP_PRE_MULT_ALPHA to
overlay capabilities. Use these instead of FEAT_GLOBAL_ALPHA,
FEAT_GLOBAL_ALPHA_VID1 and FEAT_PRE_MULT_ALPHA in code.
Remove FEAT_GLOBAL_ALPHA_VID1 and FEAT_PRE_MULT_ALPHA which are no
longer used. FEAT_GLOBAL_ALPHA is still used to decide if the HW has
global alpha register.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Archit Taneja <archit@ti.com>
Remove support for non-DISPC overlays and overlay managers.
The support to possibly have non-DISPC overlays and managers was made to
make it possible to use CPU and/or sDMA to update RFBI or DSI command
mode displays. It is ok to remove the support, because:
- No one has used the feature.
- Display update without DISPC is very slow, so it is debatable if the
update would even be usable.
- Removal cleans up code.
- If such a feature is needed later, it is better implemented outside
omapdss driver.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Archit Taneja <archit@ti.com>
Currently when changing the manager of an overlay, set_manager() directly
calls dispc to set the overlay's destination.
Change this to be more in line with other overlay configurations, and
this will also remove the need to have dispc clocks enabled when calling
set_manager().
A new field is added to overlay struct, "manager_changed". This is
similar to "display_changed" field in manager struct, and is used to
inform apply that the manager has changed and thus write to the
registers is needed.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
dsi_mux_pads() needs to know about the DSI HW module and the DSI lanes
used. Split the function into two, enable and disable, which take
necessary arguments, and add empty implementations for both.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
David reported:
Attached below is a watered-down version of rt/tst-cpuclock2.c from
GLIBC. Just build it with "gcc -o test test.c -lpthread -lrt" or
similar.
Run it several times, and you will see cases where the main thread
will measure a process clock difference before and after the nanosleep
which is smaller than the cpu-burner thread's individual thread clock
difference. This doesn't make any sense since the cpu-burner thread
is part of the top-level process's thread group.
I've reproduced this on both x86-64 and sparc64 (using both 32-bit and
64-bit binaries).
For example:
[davem@boricha build-x86_64-linux]$ ./test
process: before(0.001221967) after(0.498624371) diff(497402404)
thread: before(0.000081692) after(0.498316431) diff(498234739)
self: before(0.001223521) after(0.001240219) diff(16698)
[davem@boricha build-x86_64-linux]$
The diff of 'process' should always be >= the diff of 'thread'.
I make sure to wrap the 'thread' clock measurements the most tightly
around the nanosleep() call, and that the 'process' clock measurements
are the outer-most ones.
---
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <pthread.h>
static pthread_barrier_t barrier;
static void *chew_cpu(void *arg)
{
pthread_barrier_wait(&barrier);
while (1)
__asm__ __volatile__("" : : : "memory");
return NULL;
}
int main(void)
{
clockid_t process_clock, my_thread_clock, th_clock;
struct timespec process_before, process_after;
struct timespec me_before, me_after;
struct timespec th_before, th_after;
struct timespec sleeptime;
unsigned long diff;
pthread_t th;
int err;
err = clock_getcpuclockid(0, &process_clock);
if (err)
return 1;
err = pthread_getcpuclockid(pthread_self(), &my_thread_clock);
if (err)
return 1;
pthread_barrier_init(&barrier, NULL, 2);
err = pthread_create(&th, NULL, chew_cpu, NULL);
if (err)
return 1;
err = pthread_getcpuclockid(th, &th_clock);
if (err)
return 1;
pthread_barrier_wait(&barrier);
err = clock_gettime(process_clock, &process_before);
if (err)
return 1;
err = clock_gettime(my_thread_clock, &me_before);
if (err)
return 1;
err = clock_gettime(th_clock, &th_before);
if (err)
return 1;
sleeptime.tv_sec = 0;
sleeptime.tv_nsec = 500000000;
nanosleep(&sleeptime, NULL);
err = clock_gettime(th_clock, &th_after);
if (err)
return 1;
err = clock_gettime(my_thread_clock, &me_after);
if (err)
return 1;
err = clock_gettime(process_clock, &process_after);
if (err)
return 1;
diff = process_after.tv_nsec - process_before.tv_nsec;
printf("process: before(%lu.%.9lu) after(%lu.%.9lu) diff(%lu)\n",
process_before.tv_sec, process_before.tv_nsec,
process_after.tv_sec, process_after.tv_nsec, diff);
diff = th_after.tv_nsec - th_before.tv_nsec;
printf("thread: before(%lu.%.9lu) after(%lu.%.9lu) diff(%lu)\n",
th_before.tv_sec, th_before.tv_nsec,
th_after.tv_sec, th_after.tv_nsec, diff);
diff = me_after.tv_nsec - me_before.tv_nsec;
printf("self: before(%lu.%.9lu) after(%lu.%.9lu) diff(%lu)\n",
me_before.tv_sec, me_before.tv_nsec,
me_after.tv_sec, me_after.tv_nsec, diff);
return 0;
}
This is due to us using p->se.sum_exec_runtime in
thread_group_cputime() where we iterate the thread group and sum all
data. This does not take time since the last schedule operation (tick
or otherwise) into account. We can cure this by using
task_sched_runtime() at the cost of having to take locks.
This also means we can (and must) do away with
thread_group_sched_runtime() since the modified thread_group_cputime()
is now more accurate and would deadlock when called from
thread_group_sched_runtime().
Aside of that it makes the function safe on 32 bit systems. The old
code added t->se.sum_exec_runtime unprotected. sum_exec_runtime is a
64bit value and could be changed on another cpu at the same time.
Reported-by: David Miller <davem@davemloft.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/1314874459.7945.22.camel@twins
Tested-by: David Miller <davem@davemloft.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add a macro of_match_ptr() that allows the .of_match_table
entry in the driver structures to be assigned without having
an #ifdef xxx NULL for the case that OF is not enabled
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Add to the dev_state and alloc_async structures the user namespace
corresponding to the uid and euid. Pass these to kill_pid_info_as_uid(),
which can then implement a proper, user-namespace-aware uid check.
Changelog:
Sep 20: Per Oleg's suggestion: Instead of caching and passing user namespace,
uid, and euid each separately, pass a struct cred.
Sep 26: Address Alan Stern's comments: don't define a struct cred at
usbdev_open(), and take and put a cred at async_completed() to
ensure it lasts for the duration of kill_pid_info_as_cred().
Signed-off-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Replace calls to the Xen-specific xen_alloc_vm_area() and
xen_free_vm_area() functions with the generic equivalent
(alloc_vm_area() and free_vm_area()).
On x86, these were identical already.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Allow the xen balloon driver to populate its list of extra pages from
more than one region of memory. This will allow platforms to provide
(for example) a region of low memory and a region of high memory.
The maximum possible number of extra regions is 128 (== E820MAX) which
is quite large so xen_extra_mem is placed in __initdata. This is safe
as both xen_memory_setup() and balloon_init() are in __init.
The balloon regions themselves are not altered (i.e., there is still
only the one region).
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
In xen_memory_setup() pages that occur in gaps in the memory map are
released back to Xen. This reduces the domain's current page count in
the hypervisor. The Xen balloon driver does not correctly decrease
its initial current_pages count to reflect this. If 'delta' pages are
released and the target is adjusted the resulting reservation is
always 'delta' less than the requested target.
This affects dom0 if the initial allocation of pages overlaps the PCI
memory region but won't affect most domU guests that have been setup
with pseudo-physical memory maps that don't have gaps.
Fix this by accouting for the released pages when starting the balloon
driver.
If the domain's targets are managed by xapi, the domain may eventually
run out of memory and die because xapi currently gets its target
calculations wrong and whenever it is restarted it always reduces the
target by 'delta'.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
If we want to use granted pages for AIO, changing the mappings of a user
vma and the corresponding p2m is not enough, we also need to update the
kernel mappings accordingly.
Currently this is only needed for pages that are created for user usages
through /dev/xen/gntdev. As in, pages that have been in use by the
kernel and use the P2M will not need this special mapping.
However there are no guarantees that in the future the kernel won't
start accessing pages through the 1:1 even for internal usage.
In order to avoid the complexity of dealing with highmem, we allocated
the pages lowmem.
We issue a HYPERVISOR_grant_table_op right away in
m2p_add_override and we remove the mappings using another
HYPERVISOR_grant_table_op in m2p_remove_override.
Considering that m2p_add_override and m2p_remove_override are called
once per page we use multicalls and hypercall batching.
Use the kmap_op pointer directly as argument to do the mapping as it is
guaranteed to be present up until the unmapping is done.
Before issuing any unmapping multicalls, we need to make sure that the
mapping has already being done, because we need the kmap->handle to be
set correctly.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
[v1: Removed GRANT_FRAME_BIT usage]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Add an highmem parameter to alloc_xenballooned_pages, to allow callers to
request lowmem or highmem pages.
Fix the code style of free_xenballooned_pages' prototype.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Commit 7765be (Fix RCU_BOOST race handling current->rcu_read_unlock_special)
introduced a new ->rcu_boosted field in the task structure. This is
redundant because the existing ->rcu_boost_mutex will be non-NULL at
any time that ->rcu_boosted is nonzero. Therefore, this commit removes
->rcu_boosted and tests ->rcu_boost_mutex instead.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
We only need to constrain the compiler if we are actually exiting
the top-level RCU read-side critical section. This commit therefore
moves the first barrier() cal in __rcu_read_unlock() to inside the
"if" statement, thus avoiding needless register flushes for inner
rcu_read_unlock() calls.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The differences between rcu_assign_pointer() and RCU_INIT_POINTER() are
subtle, and it is easy to use the the cheaper RCU_INIT_POINTER() when
the more-expensive rcu_assign_pointer() should have been used instead.
The consequences of this mistake are quite severe.
This commit therefore carefully lays out the situations in which it it
permissible to use RCU_INIT_POINTER().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Recent changes to gcc give warning messages on rcu_assign_pointers()'s
checks that allow it to determine when it is OK to omit the memory
barrier. Stephen Hemminger tried a number of gcc tricks to silence
this warning, but #pragmas and CPP macros do not work together in the
way that would be required to make this work.
However, we now have RCU_INIT_POINTER(), which already omits this
memory barrier, and which therefore may be used when assigning NULL to
an RCU-protected pointer that is accessible to readers. This commit
therefore makes rcu_assign_pointer() unconditionally emit the memory
barrier.
Reported-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
RCU no longer uses this global variable, nor does anyone else. This
commit therefore removes this variable. This reduces memory footprint
and also removes some atomic instructions and memory barriers from
the dyntick-idle path.
Signed-off-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The rcu_dereference_bh_protected() and rcu_dereference_sched_protected()
macros are synonyms for rcu_dereference_protected() and are not used
anywhere in mainline. This commit therefore removes them.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Add trace events to record grace-period start and end, quiescent states,
CPUs noticing grace-period start and end, grace-period initialization,
call_rcu() invocation, tasks blocking in RCU read-side critical sections,
tasks exiting those same critical sections, force_quiescent_state()
detection of dyntick-idle and offline CPUs, CPUs entering and leaving
dyntick-idle mode (except from NMIs), CPUs coming online and going
offline, and CPUs being kicked for staying in dyntick-idle mode for too
long (as in many weeks, even on 32-bit systems).
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
rcu: Add the rcu flavor to callback trace events
The earlier trace events for registering RCU callbacks and for invoking
them did not include the RCU flavor (rcu_bh, rcu_preempt, or rcu_sched).
This commit adds the RCU flavor to those trace events.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
