Make cputime_t and cputime64_t nocast to enable sparse checking to
detect incorrect use of cputime. Drop the cputime macros for simple
scalar operations. The conversion macros are still needed.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The parent and real_parent pointers should be considered __rcu,
since they should be held under either tasklist_lock or
rcu_read_lock.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Link: http://lkml.kernel.org/r/20111214223925.GA27578@www.outflux.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Use DCB notifiers to set the skb priority to allow packets
to be steered and tagged correctly over DCB enabled drivers
that setup traffic classes.
This allows queue_mapping() routines to be removed in these
drivers that were previously inspecting the ethertype of
every skb to mark FCoE/FIP frames.
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This patch is an initial implementation for the NFC Logical Link Control
protocol. It's also known as NFC peer to peer mode.
This is a basic implementation as it lacks SDP (services Discovery
Protocol), frames aggregation support, and frame rejecion parsing.
Follow up patches will implement those missing features.
This code has been tested against a Nexus S phone implementing LLCP 1.0.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Without an API for setting and getting the local and remote general bytes,
drivers won't be able to properly establish a DEP link.
This API also allows them to propagate the remote general bytes they get
from the DEP link establishment up to the LLCP layer.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
NFC-DEP (Data Exchange Protocol) is an NFC MAC layer.
This command allows to enable and disable the DEP link on to which e.g.
LLCP can run.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This is a factorization of the current rawsock tx skb allocation routine,
as it will be used by the LLCP code.
We also rename nfc_alloc_skb to nfc_alloc_recv_skb for consistency sake.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
commit b099ce2602 (net: Batch inet_twsk_purge) added rcu protection
on tw_net for no obvious reason.
struct net are refcounted anyway since timewait sockets escape from rcu
protected sections. tw_net stay valid for the whole timwait lifetime.
This also removes a lot of sparse errors.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
It's simpler to just keep these things out until there is a real user
of them, so we can see what the needs actually are, rather than keep
these things around as useless overhead.
Signed-off-by: David S. Miller <davem@davemloft.net>
Just scratching an itch here, but it makes more sense to use the
static keyword if you think about how the compiler treats inline
functions.
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Alwin Beukers <alwin@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
The BCMA header only had definitions for 32-bit register access. Used
those as a template for the 16-bit flavour. Also changed them to inline
functions to be on the safe side. As offset parameter is used twice there
would be a problem when used like this: bcma_set32(core, offset++, val);
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Alwin Beukers <alwin@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
It is quite possible to run into a race in bss timeout where
the drivers see the bss entry just before notifying cfg80211
of a roaming event but it got timed out by the time rdev->event_work
got scehduled from cfg80211_wq. This would result in the following
WARN-ON() along with the failure to notify the user space of
the roaming. The other situation which is happening with ath6kl
that runs into issue is when the driver reports roam to same AP
event where the AP bss entry already got expired. To fix this,
move cfg80211_get_bss() from __cfg80211_roamed() to cfg80211_roamed().
[158645.538384] WARNING: at net/wireless/sme.c:586
__cfg80211_roamed+0xc2/0x1b1()
[158645.538810] Call Trace:
[158645.538838] [<c1033527>] warn_slowpath_common+0x65/0x7a
[158645.538917] [<c14cfacf>] ? __cfg80211_roamed+0xc2/0x1b1
[158645.538946] [<c103354b>] warn_slowpath_null+0xf/0x13
[158645.539055] [<c14cfacf>] __cfg80211_roamed+0xc2/0x1b1
[158645.539086] [<c14beb5b>] cfg80211_process_rdev_events+0x153/0x1cc
[158645.539166] [<c14bd57b>] cfg80211_event_work+0x26/0x36
[158645.539195] [<c10482ae>] process_one_work+0x219/0x38b
[158645.539273] [<c14bd555>] ? wiphy_new+0x419/0x419
[158645.539301] [<c10486cb>] worker_thread+0xf6/0x1bf
[158645.539379] [<c10485d5>] ? rescuer_thread+0x1b5/0x1b5
[158645.539407] [<c104b3e2>] kthread+0x62/0x67
[158645.539484] [<c104b380>] ? __init_kthread_worker+0x42/0x42
[158645.539514] [<c151309a>] kernel_thread_helper+0x6/0xd
Reported-by: Kalle Valo <kvalo@qca.qualcomm.com>
Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
1. Added module parameters sr_iov and probe_vf for controlling enablement of
SRIOV mode.
2. Increased default max num-qps, num-mpts and log_num_macs to accomodate
SRIOV mode
3. Added port_type_array as a module parameter to allow driver startup with
ports configured as desired.
In SRIOV mode, only ETH is supported, and this array is ignored; otherwise,
for the case where the FW supports both port types (ETH and IB), the
port_type_array parameter is used.
By default, the port_type_array is set to configure both ports as IB.
4. When running in sriov mode, the master needs to initialize the ICM eq table
to hold the eq's for itself and also for all the slaves.
5. mlx4_set_port_mask() now invoked from mlx4_init_hca, instead of in mlx4_dev_cap.
6. Introduced sriov VF (slave) device startup/teardown logic (mainly procedures
mlx4_init_slave, mlx4_slave_exit, mlx4_slave_cap, mlx4_slave_exit and flow
modifications in __mlx4_init_one, mlx4_init_hca, and mlx4_setup_hca).
VFs obtain their startup information from the PF (master) device via the
comm channel.
7. In SRIOV mode (both PF and VF), MSI_X must be enabled, or the driver
aborts loading the device.
8. Do not allow setting port type via sysfs when running in SRIOV mode.
9. mlx4_get_ownership: Currently, only one PF is supported by the driver.
If the HCA is burned with FW which enables more than one PF, only one
of the PFs is allowed to run. The first one up grabs a FW ownership
semaphone -- all other PFs will find that semaphore taken, and the
driver will not allow them to run.
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: Liran Liss <liranl@mellanox.co.il>
Signed-off-by: Marcel Apfelbaum <marcela@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the previous implementation mtts are managed by:
1. order - log(mtt segments), 'mtt segment' groups several mtts together.
2. first_seg - segment location relative to mtt table.
In the current implementation:
1. order - log(mtts) rather than segments
2. offset - mtt index in mtt table
Note: The actual mtt allocation is made in segments but it is
transparent to callers.
Rational: The mtt resource holders are not interested on how the allocation
of mtt is done, but rather on how they will use it.
Signed-off-by: Marcel Apfelbaum <marcela@dev.mellanox.co.il>
Reviewed-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
The physical port is now common to the PF and VFs.
The port resources and configuration is managed by the PF, VFs can
only influence the MTU of the port, it is set as max among all functions,
Each function allocates RX buffers of required size to meet it's MTU enforcement.
Port management code was moved to mlx4_core, as the mlx4_en module is
virtualization unaware
Move handling qp functionality to mlx4_get_eth_qp/mlx4_put_eth_qp
including reserve/release range and add/release unicast steering.
Let mlx4_register/unregister_mac deal only with MAC (un)registration.
Signed-off-by: Eugenia Emantayev <eugenia@mellanox.co.il>
Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
When SRIOV is enabled on the chip (at FW burning time),
the HCA uses only 17 bits for the PD. The remaining 7 high-order bits
are ignored.
Change the allocator to return only 17 bits for the PD. The MSB 7
bits will be used to encode the slave number for consistency
checking later on in the resource tracker.
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
For SRIOV, some Hypervisor commands can be executed directly (native = 1).
Others should go through the command wrapper flow (for tracking resource
usage, for example, or for changing some HCA configurations that slaves
need to be notified of).
This patch sets the groundwork for this capability -- adding the correct
value of "native" in each case.
Note that if SRIOV is not activated, this parameter has no effect.
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
Port mask now has additional state.
Port can be set as "none". In this case neither the mlx4_en or mlx4_ib
drivers take ownership of the port.
In multifunction mode there is an option to set the vfs as single ported devices.
(in single function mode, both physical ports belong to same function)
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
These changes will not affect module operation as yet. They
are only to get some structs and enums in place for use by
subsequent patches (making those smaller).
Added here:
* sriov state structs and inlines (mlx4_is_master/slave/mfunc)
* comm-channel and vhcr support structures
* enum values for new FW and comm-channel virtual commands
(i.e., commands, passed via the comm channel to the PF-driver).
* prototypes for many command wrapper functions (used by the
PF context for processing FW commands passed to it by the VFs).
* struct mlx4_eqe is moved from eq.c to mlx4.h (it will be used
by other mlx4_core source files).
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reported-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Exactly like roundup_pow_of_two(1), the rounddown version was buggy for
the case of a compile-time constant '1' argument. Probably because it
originated from the same code, sharing history with the roundup version
from before the bugfix (for that one, see commit 1a06a52ee1: "Fix
roundup_pow_of_two(1)").
However, unlike the roundup version, the fix for rounddown is to just
remove the broken special case entirely. It's simply not needed - the
generic code
1UL << ilog2(n)
does the right thing for the constant '1' argment too. The only reason
roundup needed that special case was because rounding up does so by
subtracting one from the argument (and then adding one to the result)
causing the obvious problems with "ilog2(0)".
But rounddown doesn't do any of that, since ilog2() naturally truncates
(ie "rounds down") to the right rounded down value. And without the
ilog2(0) case, there's no reason for the special case that had the wrong
value.
tl;dr: rounddown_pow_of_two(1) should be 1, not 0.
Acked-by: Dmitry Torokhov <dtor@vmware.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/cjb/mmc:
mmc: core: Fix deadlock when the CONFIG_MMC_UNSAFE_RESUME is not defined
mmc: sdhci-s3c: Remove old and misprototyped suspend operations
mmc: tmio: fix clock gating on platforms with a .set_pwr() method
mmc: sh_mmcif: fix clock gating on platforms with a .down_pwr() method
mmc: core: Fix typo at mmc_card_sleep
mmc: core: Fix power_off_notify during suspend
mmc: core: Fix setting power notify state variable for non-eMMC
mmc: core: Add quirk for long data read time
mmc: Add module.h include to sdhci-cns3xxx.c
mmc: mxcmmc: fix falling back to PIO
mmc: omap_hsmmc: DMA unmap only once in case of MMC error
This extension can be used to simulate special link layer
characteristics. Simulate because packet data is not modified, only the
calculation base is changed to delay a packet based on the original
packet size and artificial cell information.
packet_overhead can be used to simulate a link layer header compression
scheme (e.g. set packet_overhead to -20) or with a positive
packet_overhead value an additional MAC header can be simulated. It is
also possible to "replace" the 14 byte Ethernet header with something
else.
cell_size and cell_overhead can be used to simulate link layer schemes,
based on cells, like some TDMA schemes. Another application area are MAC
schemes using a link layer fragmentation with a (small) header each.
Cell size is the maximum amount of data bytes within one cell. Cell
overhead is an additional variable to change the per-cell-overhead
(e.g. 5 byte header per fragment).
Example (5 kbit/s, 20 byte per packet overhead, cell-size 100 byte, per
cell overhead 5 byte):
tc qdisc add dev eth0 root netem rate 5kbit 20 100 5
Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch uses the "tcp.limit_in_bytes" field of the kmem_cgroup to
effectively control the amount of kernel memory pinned by a cgroup.
This value is ignored in the root cgroup, and in all others,
caps the value specified by the admin in the net namespaces'
view of tcp_sysctl_mem.
If namespaces are being used, the admin is allowed to set a
value bigger than cgroup's maximum, the same way it is allowed
to set pretty much unlimited values in a real box.
Signed-off-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Hiroyouki Kamezawa <kamezawa.hiroyu@jp.fujitsu.com>
CC: David S. Miller <davem@davemloft.net>
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch allows each namespace to independently set up
its levels for tcp memory pressure thresholds. This patch
alone does not buy much: we need to make this values
per group of process somehow. This is achieved in the
patches that follows in this patchset.
Signed-off-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: David S. Miller <davem@davemloft.net>
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch introduces memory pressure controls for the tcp
protocol. It uses the generic socket memory pressure code
introduced in earlier patches, and fills in the
necessary data in cg_proto struct.
Signed-off-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com>
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The goal of this work is to move the memory pressure tcp
controls to a cgroup, instead of just relying on global
conditions.
To avoid excessive overhead in the network fast paths,
the code that accounts allocated memory to a cgroup is
hidden inside a static_branch(). This branch is patched out
until the first non-root cgroup is created. So when nobody
is using cgroups, even if it is mounted, no significant performance
penalty should be seen.
This patch handles the generic part of the code, and has nothing
tcp-specific.
Signed-off-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtsu.com>
CC: Kirill A. Shutemov <kirill@shutemov.name>
CC: David S. Miller <davem@davemloft.net>
CC: Eric W. Biederman <ebiederm@xmission.com>
CC: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch replaces all uses of struct sock fields' memory_pressure,
memory_allocated, sockets_allocated, and sysctl_mem to acessor
macros. Those macros can either receive a socket argument, or a mem_cgroup
argument, depending on the context they live in.
Since we're only doing a macro wrapping here, no performance impact at all is
expected in the case where we don't have cgroups disabled.
Signed-off-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Hiroyouki Kamezawa <kamezawa.hiroyu@jp.fujitsu.com>
CC: David S. Miller <davem@davemloft.net>
CC: Eric W. Biederman <ebiederm@xmission.com>
CC: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Instead of testing defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The current rcu_batch_end event trace records only the name of the RCU
flavor and the total number of callbacks that remain queued on the
current CPU. This is insufficient for testing and tuning the new
dyntick-idle RCU_FAST_NO_HZ code, so this commit adds idle state along
with whether or not any of the callbacks that were ready to invoke
at the beginning of rcu_do_batch() are still queued.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
When architectures register CPUs, they indicate whether the CPU allows
hotplugging; notably, x86 and ARM don't allow hotplugging CPU 0.
Userspace can easily query the hotpluggability of a CPU via sysfs;
however, the kernel has no convenient way of accessing that property in
an architecture-independent way. While the kernel can simply try it and
see, some code needs to distinguish between "hotplug failed" and
"hotplug has no hope of working on this CPU"; for example, rcutorture's
CPU hotplug tests want to avoid drowning out real hotplug failures with
expected failures.
Expose this property via a new cpu_is_hotpluggable function, so that the
rest of the kernel can access it in an architecture-independent way.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The current implementation of RCU_FAST_NO_HZ prevents CPUs from entering
dyntick-idle state if they have RCU callbacks pending. Unfortunately,
this has the side-effect of often preventing them from entering this
state, especially if at least one other CPU is not in dyntick-idle state.
However, the resulting per-tick wakeup is wasteful in many cases: if the
CPU has already fully responded to the current RCU grace period, there
will be nothing for it to do until this grace period ends, which will
frequently take several jiffies.
This commit therefore permits a CPU that has done everything that the
current grace period has asked of it (rcu_pending() == 0) even if it
still as RCU callbacks pending. However, such a CPU posts a timer to
wake it up several jiffies later (6 jiffies, based on experience with
grace-period lengths). This wakeup is required to handle situations
that can result in all CPUs being in dyntick-idle mode, thus failing
to ever complete the current grace period. If a CPU wakes up before
the timer goes off, then it cancels that timer, thus avoiding spurious
wakeups.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The intent is that a given RCU read-side critical section be confined
to a single context. For example, it is illegal to invoke rcu_read_lock()
in an exception handler and then invoke rcu_read_unlock() from the
context of the task that received the exception.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
With the new implementation of RCU_FAST_NO_HZ, it was possible to hang
RCU grace periods as follows:
o CPU 0 attempts to go idle, cycles several times through the
rcu_prepare_for_idle() loop, then goes dyntick-idle when
RCU needs nothing more from it, while still having at least
on RCU callback pending.
o CPU 1 goes idle with no callbacks.
Both CPUs can then stay in dyntick-idle mode indefinitely, preventing
the RCU grace period from ever completing, possibly hanging the system.
This commit therefore prevents CPUs that have RCU callbacks from entering
dyntick-idle mode. This approach also eliminates the need for the
end-of-grace-period IPIs used previously.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit adds trace_rcu_prep_idle(), which is invoked from
rcu_prepare_for_idle() and rcu_wake_cpu() to trace attempts on
the part of RCU to force CPUs into dyntick-idle mode.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit updates the trace_rcu_dyntick() header comment to reflect
events added by commit 4b4f421.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Those two APIs were provided to optimize the calls of
tick_nohz_idle_enter() and rcu_idle_enter() into a single
irq disabled section. This way no interrupt happening in-between would
needlessly process any RCU job.
Now we are talking about an optimization for which benefits
have yet to be measured. Let's start simple and completely decouple
idle rcu and dyntick idle logics to simplify.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Commit 908a3283 (Fix idle_cpu()) invalidated some uses of idle_cpu(),
which used to say whether or not the CPU was running the idle task,
but now instead says whether or not the CPU is running the idle task
in the absence of pending wakeups. Although this new implementation
gives a better answer to the question "is this CPU idle?", it also
invalidates other uses that were made of idle_cpu().
This commit therefore introduces a new is_idle_task() API member
that determines whether or not the specified task is one of the
idle tasks, allowing open-coded "->pid == 0" sequences to be replaced
by something more meaningful.
Suggested-by: Josh Triplett <josh@joshtriplett.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The trace_rcu_dyntick() trace event did not print both the old and
the new value of the nesting level, and furthermore printed only
the low-order 32 bits of it. This could result in some confusion
when interpreting trace-event dumps, so this commit prints both
the old and the new value, prints the full 64 bits, and also selects
the process-entry/exit increment to print nicely in hexadecimal.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
The RCU implementations, including SRCU, are designed to be used in a
lock-like fashion, so that the read-side lock and unlock primitives must
execute in the same context for any given read-side critical section.
This constraint is enforced by lockdep-RCU. However, there is a need
to enter an SRCU read-side critical section within the context of an
exception and then exit in the context of the task that encountered the
exception. The cost of this capability is that the read-side operations
incur the overhead of disabling interrupts.
Note that although the current implementation allows a given read-side
critical section to be entered by one task and then exited by another, all
known possible implementations that allow this have scalability problems.
Therefore, a given read-side critical section must be exited by the same
task that entered it, though perhaps from an interrupt or exception
handler running within that task's context. But if you are thinking
in terms of interrupt handlers, make sure that you have considered the
possibility of threaded interrupt handlers.
Credit goes to Peter Zijlstra for suggesting use of the existing _raw
suffix to indicate disabling lockdep over the earlier "bulkref" names.
Requested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
It is assumed that rcu won't be used once we switch to tickless
mode and until we restart the tick. However this is not always
true, as in x86-64 where we dereference the idle notifiers after
the tick is stopped.
To prepare for fixing this, add two new APIs:
tick_nohz_idle_enter_norcu() and tick_nohz_idle_exit_norcu().
If no use of RCU is made in the idle loop between
tick_nohz_enter_idle() and tick_nohz_exit_idle() calls, the arch
must instead call the new *_norcu() version such that the arch doesn't
need to call rcu_idle_enter() and rcu_idle_exit().
Otherwise the arch must call tick_nohz_enter_idle() and
tick_nohz_exit_idle() and also call explicitly:
- rcu_idle_enter() after its last use of RCU before the CPU is put
to sleep.
- rcu_idle_exit() before the first use of RCU after the CPU is woken
up.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: David Miller <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The tick_nohz_stop_sched_tick() function, which tries to delay
the next timer tick as long as possible, can be called from two
places:
- From the idle loop to start the dytick idle mode
- From interrupt exit if we have interrupted the dyntick
idle mode, so that we reprogram the next tick event in
case the irq changed some internal state that requires this
action.
There are only few minor differences between both that
are handled by that function, driven by the ts->inidle
cpu variable and the inidle parameter. The whole guarantees
that we only update the dyntick mode on irq exit if we actually
interrupted the dyntick idle mode, and that we enter in RCU extended
quiescent state from idle loop entry only.
Split this function into:
- tick_nohz_idle_enter(), which sets ts->inidle to 1, enters
dynticks idle mode unconditionally if it can, and enters into RCU
extended quiescent state.
- tick_nohz_irq_exit() which only updates the dynticks idle mode
when ts->inidle is set (ie: if tick_nohz_idle_enter() has been called).
To maintain symmetry, tick_nohz_restart_sched_tick() has been renamed
into tick_nohz_idle_exit().
This simplifies the code and micro-optimize the irq exit path (no need
for local_irq_save there). This also prepares for the split between
dynticks and rcu extended quiescent state logics. We'll need this split to
further fix illegal uses of RCU in extended quiescent states in the idle
loop.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: David Miller <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
A common debug_lockdep_rcu_enabled() function is used to check whether
RCU lockdep splats should be reported, but srcu_read_lock() does not
use it. This commit therefore brings srcu_read_lock_held() up to date.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
