Removing explicit calls to mmiowb() from driver code means that we must
now call into the generic mmiowb_spin_{lock,unlock}() functions from the
core spinlock code. In order to elide barriers following critical
sections without any I/O writes, we also hook into the asm-generic I/O
routines.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Previously, alloc_ila_locks() and bucket_table_alloc() call
spin_lock_init() separately, therefore they have two different
lock names and lock class keys. However, after commit b893281715
("ila: Call library function alloc_bucket_locks") they both call
helper alloc_bucket_spinlocks() which now only has one lock
name and lock class key. This causes a few bogus lockdep warnings
as reported by syzbot.
Fix this by making alloc_bucket_locks() a macro and pass declaration
name as lock name and a static lock class key inside the macro.
Fixes: b893281715 ("ila: Call library function alloc_bucket_locks")
Reported-by: <syzbot+b66a5a554991a8ed027c@syzkaller.appspotmail.com>
Cc: Tom Herbert <tom@quantonium.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
There are in-tree users of atomic_dec_and_lock() which must acquire the
spin lock with interrupts disabled. To workaround the lack of an irqsave
variant of atomic_dec_and_lock() they use local_irq_save() at the call
site. This causes extra code and creates in some places unneeded long
interrupt disabled times. These places need also extra treatment for
PREEMPT_RT due to the disconnect of the irq disabling and the lock
function.
Implement the missing irqsave variant of the function.
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r20180612161621.22645-3-bigeasy@linutronix.de
Three sets of overlapping changes, two in the packet scheduler
and one in the meson-gxl PHY driver.
Signed-off-by: David S. Miller <davem@davemloft.net>
When CONFIG_GENERIC_LOCKBEAK=y, locking structures grow an extra int ->break_lock
field which is used to implement raw_spin_is_contended() by setting the field
to 1 when waiting on a lock and clearing it to zero when holding a lock.
However, there are a few problems with this approach:
- There is a write-write race between a CPU successfully taking the lock
(and subsequently writing break_lock = 0) and a waiter waiting on
the lock (and subsequently writing break_lock = 1). This could result
in a contended lock being reported as uncontended and vice-versa.
- On machines with store buffers, nothing guarantees that the writes
to break_lock are visible to other CPUs at any particular time.
- READ_ONCE/WRITE_ONCE are not used, so the field is potentially
susceptible to harmful compiler optimisations,
Consequently, the usefulness of this field is unclear and we'd be better off
removing it and allowing architectures to implement raw_spin_is_contended() by
providing a definition of arch_spin_is_contended(), as they can when
CONFIG_GENERIC_LOCKBREAK=n.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1511894539-7988-3-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add two new library functions: alloc_bucket_spinlocks and
free_bucket_spinlocks. These are used to allocate and free an array
of spinlocks that are useful as locks for hash buckets. The interface
specifies the maximum number of spinlocks in the array as well
as a CPU multiplier to derive the number of spinlocks to allocate.
The number allocated is rounded up to a power of two to make the
array amenable to hash lookup.
Signed-off-by: Tom Herbert <tom@quantonium.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Outside of the locking code itself, {read,spin,write}_can_lock() have no
users in tree. Apparmor (the last remaining user of write_can_lock()) got
moved over to lockdep by the previous patch.
This patch removes the use of {read,spin,write}_can_lock() from the
BUILD_LOCK_OPS macro, deferring to the trylock operation for testing the
lock status, and subsequently removes the unused macros altogether. They
aren't guaranteed to work in a concurrent environment and can give
incorrect results in the case of qrwlock.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1507055129-12300-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull locking updates from Ingo Molnar:
- Add 'cross-release' support to lockdep, which allows APIs like
completions, where it's not the 'owner' who releases the lock, to be
tracked. It's all activated automatically under
CONFIG_PROVE_LOCKING=y.
- Clean up (restructure) the x86 atomics op implementation to be more
readable, in preparation of KASAN annotations. (Dmitry Vyukov)
- Fix static keys (Paolo Bonzini)
- Add killable versions of down_read() et al (Kirill Tkhai)
- Rework and fix jump_label locking (Marc Zyngier, Paolo Bonzini)
- Rework (and fix) tlb_flush_pending() barriers (Peter Zijlstra)
- Remove smp_mb__before_spinlock() and convert its usages, introduce
smp_mb__after_spinlock() (Peter Zijlstra)
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (56 commits)
locking/lockdep/selftests: Fix mixed read-write ABBA tests
sched/completion: Avoid unnecessary stack allocation for COMPLETION_INITIALIZER_ONSTACK()
acpi/nfit: Fix COMPLETION_INITIALIZER_ONSTACK() abuse
locking/pvqspinlock: Relax cmpxchg's to improve performance on some architectures
smp: Avoid using two cache lines for struct call_single_data
locking/lockdep: Untangle xhlock history save/restore from task independence
locking/refcounts, x86/asm: Disable CONFIG_ARCH_HAS_REFCOUNT for the time being
futex: Remove duplicated code and fix undefined behaviour
Documentation/locking/atomic: Finish the document...
locking/lockdep: Fix workqueue crossrelease annotation
workqueue/lockdep: 'Fix' flush_work() annotation
locking/lockdep/selftests: Add mixed read-write ABBA tests
mm, locking/barriers: Clarify tlb_flush_pending() barriers
locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS truly non-interactive
locking/lockdep: Explicitly initialize wq_barrier::done::map
locking/lockdep: Rename CONFIG_LOCKDEP_COMPLETE to CONFIG_LOCKDEP_COMPLETIONS
locking/lockdep: Reword title of LOCKDEP_CROSSRELEASE config
locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE part of CONFIG_PROVE_LOCKING
locking/refcounts, x86/asm: Implement fast refcount overflow protection
locking/lockdep: Fix the rollback and overwrite detection logic in crossrelease
...
Since its inception, our understanding of ACQUIRE, esp. as applied to
spinlocks, has changed somewhat. Also, I wonder if, with a simple
change, we cannot make it provide more.
The problem with the comment is that the STORE done by spin_lock isn't
itself ordered by the ACQUIRE, and therefore a later LOAD can pass over
it and cross with any prior STORE, rendering the default WMB
insufficient (pointed out by Alan).
Now, this is only really a problem on PowerPC and ARM64, both of
which already defined smp_mb__before_spinlock() as a smp_mb().
At the same time, we can get a much stronger construct if we place
that same barrier _inside_ the spin_lock(). In that case we upgrade
the RCpc spinlock to an RCsc. That would make all schedule() calls
fully transitive against one another.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is still considerable confusion as to the semantics of
spin_unlock_wait(), but there seems to be universal agreement that
it is not that of a lock/unlock pair. This commit therefore removes
the comment added by 6016ffc387 ("atomics: Add header comment so
spin_unlock_wait()") in order to prevent at least that flavor of
confusion.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
There is material describing the ordering guarantees provided by
spin_unlock_wait(), but it is not necessarily easy to find. This commit
therefore adds a docbook header comment to this function informally
describing its semantics.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Pull x86 asm changes from Ingo Molnar:
"The biggest changes in this cycle were:
- Revamp, simplify (and in some cases fix) Time Stamp Counter (TSC)
primitives. (Andy Lutomirski)
- Add new, comprehensible entry and exit handlers written in C.
(Andy Lutomirski)
- vm86 mode cleanups and fixes. (Brian Gerst)
- 32-bit compat code cleanups. (Brian Gerst)
The amount of simplification in low level assembly code is already
palpable:
arch/x86/entry/entry_32.S | 130 +----
arch/x86/entry/entry_64.S | 197 ++-----
but more simplifications are planned.
There's also the usual laudry mix of low level changes - see the
changelog for details"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (83 commits)
x86/asm: Drop repeated macro of X86_EFLAGS_AC definition
x86/asm/msr: Make wrmsrl() a function
x86/asm/delay: Introduce an MWAITX-based delay with a configurable timer
x86/asm: Add MONITORX/MWAITX instruction support
x86/traps: Weaken context tracking entry assertions
x86/asm/tsc: Add rdtscll() merge helper
selftests/x86: Add syscall_nt selftest
selftests/x86: Disable sigreturn_64
x86/vdso: Emit a GNU hash
x86/entry: Remove do_notify_resume(), syscall_trace_leave(), and their TIF masks
x86/entry/32: Migrate to C exit path
x86/entry/32: Remove 32-bit syscall audit optimizations
x86/vm86: Rename vm86->v86flags and v86mask
x86/vm86: Rename vm86->vm86_info to user_vm86
x86/vm86: Clean up vm86.h includes
x86/vm86: Move the vm86 IRQ definitions to vm86.h
x86/vm86: Use the normal pt_regs area for vm86
x86/vm86: Eliminate 'struct kernel_vm86_struct'
x86/vm86: Move fields from 'struct kernel_vm86_struct' to 'struct vm86'
x86/vm86: Move vm86 fields out of 'thread_struct'
...
With both gcc 4.7.2 and 4.9.2, sometimes GCC mysteriously
doesn't inline very small functions we expect to be inlined.
See:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122
In particular, with this config:
http://busybox.net/~vda/kernel_config
there are more than a thousand copies of tiny spinlock-related
functions:
$ nm --size-sort vmlinux | grep -iF ' t ' | uniq -c | grep -v '^ *1 ' | sort -rn | grep ' spin'
473 000000000000000b t spin_unlock_irqrestore
292 000000000000000b t spin_unlock
215 000000000000000b t spin_lock
134 000000000000000b t spin_unlock_irq
130 000000000000000b t spin_unlock_bh
120 000000000000000b t spin_lock_irq
106 000000000000000b t spin_lock_bh
Disassembly:
ffffffff81004720 <spin_lock>:
ffffffff81004720: 55 push %rbp
ffffffff81004721: 48 89 e5 mov %rsp,%rbp
ffffffff81004724: e8 f8 4e e2 02 callq <_raw_spin_lock>
ffffffff81004729: 5d pop %rbp
ffffffff8100472a: c3 retq
This patch fixes this via s/inline/__always_inline/ in
spinlock.h. This decreases vmlinux by about 40k:
text data bss dec hex filename
82375570 22255544 20627456 125258570 7774b4a vmlinux.before
82335059 22255416 20627456 125217931 776ac8b vmlinux
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Graf <tgraf@suug.ch>
Link: http://lkml.kernel.org/r/1436812263-15243-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Our current documentation claims that, when followed by an ACQUIRE,
smp_mb__before_spinlock() orders prior loads against subsequent loads
and stores, which isn't the intent. This commit therefore fixes the
documentation to state that this sequence orders only prior stores
against subsequent loads and stores.
In addition, the original intent of smp_mb__before_spinlock() was to only
order prior loads against subsequent stores, however, people have started
using it as if it ordered prior loads against subsequent loads and stores.
This commit therefore also updates smp_mb__before_spinlock()'s header
comment to reflect this new reality.
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
