So I've noticed a number of instances where it was not obvious from the
code whether ->task_list was for a wait-queue head or a wait-queue entry.
Furthermore, there's a number of wait-queue users where the lists are
not for 'tasks' but other entities (poll tables, etc.), in which case
the 'task_list' name is actively confusing.
To clear this all up, name the wait-queue head and entry list structure
fields unambiguously:
struct wait_queue_head::task_list => ::head
struct wait_queue_entry::task_list => ::entry
For example, this code:
rqw->wait.task_list.next != &wait->task_list
... is was pretty unclear (to me) what it's doing, while now it's written this way:
rqw->wait.head.next != &wait->entry
... which makes it pretty clear that we are iterating a list until we see the head.
Other examples are:
list_for_each_entry_safe(pos, next, &x->task_list, task_list) {
list_for_each_entry(wq, &fence->wait.task_list, task_list) {
... where it's unclear (to me) what we are iterating, and during review it's
hard to tell whether it's trying to walk a wait-queue entry (which would be
a bug), while now it's written as:
list_for_each_entry_safe(pos, next, &x->head, entry) {
list_for_each_entry(wq, &fence->wait.head, entry) {
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The wait_bit*() types and APIs are mixed into wait.h, but they
are a pretty orthogonal extension of wait-queues.
Furthermore, only about 50 kernel files use these APIs, while
over 1000 use the regular wait-queue functionality.
So clean up the main wait.h by moving the wait-bit functionality
out of it, into a separate .h and .c file:
include/linux/wait_bit.h for types and APIs
kernel/sched/wait_bit.c for the implementation
Update all header dependencies.
This reduces the size of wait.h rather significantly, by about 30%.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So there's over 300 CPP macro line-continuation backslashes in
include/linux/wait.h (!!), which are aligned vertically to make
the macro maze a bit more navigable.
The recent renames and reorganization broke some of them, and
instead of re-aligning them in every patch (which would add
a lot of stylistic noise to the patches and make them less
readable), I just ignored them - and fixed them up in a single
go in this patch.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Contrary to kernel tradition, most of the bit-wait function prototypes
in <linux/wait.h> don't fully define the parameter names, they only
list the types:
int out_of_line_wait_on_bit_timeout(void *, int, wait_bit_action_f *, unsigned, unsigned long);
... which is pretty passive-aggressive in terms of informing the reader
about what these functions are doing.
Fill in the parameter names, such as:
int out_of_line_wait_on_bit_timeout(void *word, int, wait_bit_action_f *action, unsigned int mode, unsigned long timeout);
Also turn spurious (and inconsistently utilized) cases of 'unsigned' into 'unsigned int'.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So wait-bit-queue head variables are often named:
struct wait_bit_queue *q
... which is a bit ambiguous and super confusing, because
they clearly suggest wait-queue head semantics and behavior
(they rhyme with the old wait_queue_t *q naming), while they
are extended wait-queue _entries_, not heads!
They are misnomers in two ways:
- the 'wait_bit_queue' leaves open the question of whether
it's an entry or a head
- the 'q' parameter and local variable naming falsely implies
that it's a 'queue' - while it's an entry.
This resulted in sometimes confusing cases such as:
finish_wait(wq, &q->wait);
where the 'q' is not a wait-queue head, but a wait-bit-queue entry.
So improve this all by standardizing wait-bit-queue nomenclature
similar to wait-queue head naming:
struct wait_bit_queue => struct wait_bit_queue_entry
q => wbq_entry
Which makes it all a much clearer:
struct wait_bit_queue_entry *wbq_entry
... and turns the former confusing piece of code into:
finish_wait(wq_head, &wbq_entry->wq_entry;
which IMHO makes it apparently clear what we are doing,
without having to analyze the context of the code: we are
adding a wait-queue entry to a regular wait-queue head,
which entry is embedded in a wait-bit-queue entry.
I'm not a big fan of acronyms, but repeating wait_bit_queue_entry
in field and local variable names is too long, so Hopefully it's
clear enough that 'wq_' prefixes stand for wait-queues, while
'wbq_' prefixes stand for wait-bit-queues.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The wait-queue head parameters and variables are named in a
couple of ways, we have the following variants currently:
wait_queue_head_t *q
wait_queue_head_t *wq
wait_queue_head_t *head
In particular the 'wq' naming is ambiguous in the sense whether it's
a wait-queue head or entry name - as entries were often named 'wait'.
( Not to mention the confusion of any readers coming over from
workqueue-land. )
Standardize all this around a single, unambiguous parameter and
variable name:
struct wait_queue_head *wq_head
which is easy to grep for and also rhymes nicely with the wait-queue
entry naming:
struct wait_queue_entry *wq_entry
Also rename:
struct __wait_queue_head => struct wait_queue_head
... and use this struct type to migrate from typedefs usage to 'struct'
usage, which is more in line with existing kernel practices.
Don't touch any external users and preserve the main wait_queue_head_t
typedef.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So the various wait-queue entry variables in include/linux/wait.h
and kernel/sched/wait.c are named in a colorfully inconsistent
way:
wait_queue_entry_t *wait
wait_queue_entry_t *__wait (even in plain C code!)
wait_queue_entry_t *q (!)
wait_queue_entry_t *new (making anyone who knows C++ cringe)
wait_queue_entry_t *old
I think part of the reason for the inconsistency is the constant
apparent confusion about what a wait queue 'head' versus 'entry' is.
( Some of the documentation talks about a 'wait descriptor', which is
the wait-queue entry itself - further adding to the confusion. )
The most common name is 'wait', but that in itself is somewhat
ambiguous as well, as it does not really make it clear whether
it's a wait-queue entry or head.
To improve all this name the wait-queue entry structure parameters
and variables consistently and push through this naming into all
the wait.h and wait.c code:
struct wait_queue_entry *wq_entry
The 'wq_' prefix makes it easy to grep for, and we also use the
opportunity to move away from the typedef to a plain 'struct' naming:
in the kernel we typically reserve typedefs for cases where a
C structure is really small and somewhat opaque - such as pte_t.
wait-queue entries are neither small nor opaque, so use the more
standard 'struct xxx_entry' list management code nomenclature instead.
( We don't touch external users, and we preserve the typedef as well
for actual wait-queue users, to reduce unnecessary churn. )
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Rename:
wait_queue_t => wait_queue_entry_t
'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue",
but in reality it's a queue *entry*. The 'real' queue is the wait queue head,
which had to carry the name.
Start sorting this out by renaming it to 'wait_queue_entry_t'.
This also allows the real structure name 'struct __wait_queue' to
lose its double underscore and become 'struct wait_queue_entry',
which is the more canonical nomenclature for such data types.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The scheduler header file split and cleanups ended up exposing a few
nasty header file dependencies, and in particular it showed how we in
<linux/wait.h> ended up depending on "signal_pending()", which now comes
from <linux/sched/signal.h>.
That's a very subtle and annoying dependency, which already caused a
semantic merge conflict (see commit e58bc92783 "Pull overlayfs updates
from Miklos Szeredi", which added that fixup in the merge commit).
It turns out that we can avoid this dependency _and_ improve code
generation by moving the guts of the fairly nasty helper #define
__wait_event_interruptible_locked() to out-of-line code. The code that
includes the signal_pending() check is all in the slow-path where we
actually go to sleep waiting for the event anyway, so using a helper
function is the right thing to do.
Using a helper function is also what we already did for the non-locked
versions, see the "__wait_event*()" macros and the "prepare_to_wait*()"
set of helper functions.
We might want to try to unify all these macro games, we have a _lot_ of
subtly different wait-event loops. But this is the minimal patch to fix
the annoying header dependency.
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add #include <linux/cred.h> dependencies to all .c files rely on sched.h
doing that for them.
Note that even if the count where we need to add extra headers seems high,
it's still a net win, because <linux/sched.h> is included in over
2,200 files ...
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
ktime is a union because the initial implementation stored the time in
scalar nanoseconds on 64 bit machine and in a endianess optimized timespec
variant for 32bit machines. The Y2038 cleanup removed the timespec variant
and switched everything to scalar nanoseconds. The union remained, but
become completely pointless.
Get rid of the union and just keep ktime_t as simple typedef of type s64.
The conversion was done with coccinelle and some manual mopping up.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Otherwise this logic only works if mode is "compatible" with another
exclusive waiter.
If some wq has both TASK_INTERRUPTIBLE and TASK_UNINTERRUPTIBLE waiters,
abort_exclusive_wait() won't wait an uninterruptible waiter.
The main user is __wait_on_bit_lock() and currently it is fine but only
because TASK_KILLABLE includes TASK_UNINTERRUPTIBLE and we do not have
lock_page_interruptible() yet.
Just use TASK_NORMAL and remove the "mode" arg from abort_exclusive_wait().
Yes, this means that (say) wake_up_interruptible() can wake up the non-
interruptible waiter(s), but I think this is fine. And in fact I think
that abort_exclusive_wait() must die, see the next change.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160906140047.GA6157@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull networking updates from Davic Miller:
1) Support busy polling generically, for all NAPI drivers. From Eric
Dumazet.
2) Add byte/packet counter support to nft_ct, from Floriani Westphal.
3) Add RSS/XPS support to mvneta driver, from Gregory Clement.
4) Implement IPV6_HDRINCL socket option for raw sockets, from Hannes
Frederic Sowa.
5) Add support for T6 adapter to cxgb4 driver, from Hariprasad Shenai.
6) Add support for VLAN device bridging to mlxsw switch driver, from
Ido Schimmel.
7) Add driver for Netronome NFP4000/NFP6000, from Jakub Kicinski.
8) Provide hwmon interface to mlxsw switch driver, from Jiri Pirko.
9) Reorganize wireless drivers into per-vendor directories just like we
do for ethernet drivers. From Kalle Valo.
10) Provide a way for administrators "destroy" connected sockets via the
SOCK_DESTROY socket netlink diag operation. From Lorenzo Colitti.
11) Add support to add/remove multicast routes via netlink, from Nikolay
Aleksandrov.
12) Make TCP keepalive settings per-namespace, from Nikolay Borisov.
13) Add forwarding and packet duplication facilities to nf_tables, from
Pablo Neira Ayuso.
14) Dead route support in MPLS, from Roopa Prabhu.
15) TSO support for thunderx chips, from Sunil Goutham.
16) Add driver for IBM's System i/p VNIC protocol, from Thomas Falcon.
17) Rationalize, consolidate, and more completely document the checksum
offloading facilities in the networking stack. From Tom Herbert.
18) Support aborting an ongoing scan in mac80211/cfg80211, from
Vidyullatha Kanchanapally.
19) Use per-bucket spinlock for bpf hash facility, from Tom Leiming.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1375 commits)
net: bnxt: always return values from _bnxt_get_max_rings
net: bpf: reject invalid shifts
phonet: properly unshare skbs in phonet_rcv()
dwc_eth_qos: Fix dma address for multi-fragment skbs
phy: remove an unneeded condition
mdio: remove an unneed condition
mdio_bus: NULL dereference on allocation error
net: Fix typo in netdev_intersect_features
net: freescale: mac-fec: Fix build error from phy_device API change
net: freescale: ucc_geth: Fix build error from phy_device API change
bonding: Prevent IPv6 link local address on enslaved devices
IB/mlx5: Add flow steering support
net/mlx5_core: Export flow steering API
net/mlx5_core: Make ipv4/ipv6 location more clear
net/mlx5_core: Enable flow steering support for the IB driver
net/mlx5_core: Initialize namespaces only when supported by device
net/mlx5_core: Set priority attributes
net/mlx5_core: Connect flow tables
net/mlx5_core: Introduce modify flow table command
net/mlx5_core: Managing root flow table
...
Conflicts:
drivers/net/geneve.c
Here we had an overlapping change, where in 'net' the extraneous stats
bump was being removed whilst in 'net-next' the final argument to
udp_tunnel6_xmit_skb() was being changed.
Signed-off-by: David S. Miller <davem@davemloft.net>
Jan Stancek reported that I wrecked things for him by fixing things for
Vladimir :/
His report was due to an UNINTERRUPTIBLE wait getting -EINTR, which
should not be possible, however my previous patch made this possible by
unconditionally checking signal_pending().
We cannot use current->state as was done previously, because the
instruction after the store to that variable it can be changed. We must
instead pass the initial state along and use that.
Fixes: 68985633bc ("sched/wait: Fix signal handling in bit wait helpers")
Reported-by: Jan Stancek <jstancek@redhat.com>
Reported-by: Chris Mason <clm@fb.com>
Tested-by: Jan Stancek <jstancek@redhat.com>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Chris Mason <clm@fb.com>
Reviewed-by: Paul Turner <pjt@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: tglx@linutronix.de
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: hpa@zytor.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The memory barrier in the helper wq_has_sleeper is needed by just
about every user of waitqueue_active. This patch generalises it
by making it take a wait_queue_head_t directly. The existing
helper is renamed to skwq_has_sleeper.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This reverts commit 51360155ec and adapts
fs/userfaultfd.c to use the old version of that function.
It didn't look robust to call __wake_up_common with "nr == 1" when we
absolutely require wakeall semantics, but we've full control of what we
insert in the two waitqueue heads of the blocked userfaults. No
exclusive waitqueue risks to be inserted into those two waitqueue heads
so we can as well stick to "nr == 1" of the old code and we can rely
purely on the fact no waitqueue inserted in one of the two waitqueue
heads we must enforce as wakeall, has wait->flags WQ_FLAG_EXCLUSIVE set.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
