A number of situations currently require the heavyweight smp_mb(),
even though there is no need to order prior stores against later
loads. Many architectures have much cheaper ways to handle these
situations, but the Linux kernel currently has no portable way
to make use of them.
This commit therefore supplies smp_load_acquire() and
smp_store_release() to remedy this situation. The new
smp_load_acquire() primitive orders the specified load against
any subsequent reads or writes, while the new smp_store_release()
primitive orders the specifed store against any prior reads or
writes. These primitives allow array-based circular FIFOs to be
implemented without an smp_mb(), and also allow a theoretical
hole in rcu_assign_pointer() to be closed at no additional
expense on most architectures.
In addition, the RCU experience transitioning from explicit
smp_read_barrier_depends() and smp_wmb() to rcu_dereference()
and rcu_assign_pointer(), respectively resulted in substantial
improvements in readability. It therefore seems likely that
replacing other explicit barriers with smp_load_acquire() and
smp_store_release() will provide similar benefits. It appears
that roughly half of the explicit barriers in core kernel code
might be so replaced.
[Changelog by PaulMck]
(cherry picked from commit 47933ad41a)
Reviewed-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Victor Kaplansky <VICTORK@il.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/20131213150640.908486364@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull MIPS fixes from Ralf Baechle:
"Resurrect Alchemy platforms by invoking the WAIT instructions with
interrupts enabled. This still leaves the race condition between
testing TIF_NEED_RESCHED and the WAIT instruction for Alchemy
platforms which need a different fix than other MIPS platforms. But
at least it gets MIPS platforms flying again.
There are also fixes for two build errors (CONFIG_FTRACE=y with
CONFIG_DYNAMIC_FTRACE=n) and CONFIG_VIRTUALIZATION without CONFIG_KVM"
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
MIPS: ftrace: Add missing CONFIG_DYNAMIC_FTRACE
MIPS: include: mmu_context.h: Replace VIRTUALIZATION with KVM
MIPS: Alchemy: fix wait function
Pull kvm bugfixes from Gleb Natapov:
"There is one more fix for MIPS KVM ABI here, MIPS and PPC build
breakage fixes and a couple of PPC bug fixes"
* 'fixes' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
kvm/ppc/booke64: Fix lazy ee handling in kvmppc_handle_exit()
kvm/ppc/booke: Hold srcu lock when calling gfn functions
kvm/ppc/booke64: Disable e6500 support
kvm/ppc/booke64: Fix AltiVec interrupt numbers and build breakage
mips/kvm: Use KVM_REG_MIPS and proper size indicators for *_ONE_REG
kvm: Add definition of KVM_REG_MIPS
KVM: add kvm_para_available to asm-generic/kvm_para.h
The API requires that the GET_ONE_REG and SET_ONE_REG ioctls have this
extra information encoded in the register identifiers.
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
arch_ftrace_update_code and ftrace_modify_all_code are only
available if CONFIG_DYNAMIC_FTRACE is selected.
Fixes the following build problem on MIPS randconfig:
arch/mips/kernel/ftrace.c: In function 'arch_ftrace_update_code':
arch/mips/kernel/ftrace.c:31:2: error: implicit declaration of function
'ftrace_modify_all_code' [-Werror=implicit-function-declaration]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Acked-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5435/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The kvm_* symbols are only available if KVM is selected.
Fixes the following linking problem on a randconfig:
arch/mips/built-in.o: In function `local_flush_tlb_mm':
(.text+0x18a94): undefined reference to `kvm_local_flush_tlb_all'
arch/mips/built-in.o: In function `local_flush_tlb_range':
(.text+0x18d0c): undefined reference to `kvm_local_flush_tlb_all'
kernel/built-in.o: In function `__schedule':
core.c:(.sched.text+0x2a00): undefined reference to `kvm_local_flush_tlb_all'
mm/built-in.o: In function `use_mm':
(.text+0x30214): undefined reference to `kvm_local_flush_tlb_all'
fs/built-in.o: In function `flush_old_exec':
(.text+0xf0a0): undefined reference to `kvm_local_flush_tlb_all'
make: *** [vmlinux] Error 1
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Acked-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5437/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Only an interrupt can wake the core from 'wait', enable interrupts
locally before executing 'wait'.
[ralf@linux-mips.org: This leave the race between an interrupt that's
setting TIF_NEED_RESCHEd and entering the WAIT status. but at least it's
going to bring Alchemy back from the dead, so I'm going to apply this
patch.]
Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/5408/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Pull MIPS fixes from Ralf Baechle:
"MIPS fixes across the field. The only area that's standing out is the
exception handling which received it's dose of breakage as part of the
microMIPS patchset"
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
MIPS: ralink: add missing SZ_1M multiplier
MIPS: Compat: Fix cputime_to_timeval() arguments in compat binfmt_elf.
MIPS: OCTEON: Improve _machine_halt implementation.
MIPS: rtlx: Fix implicit declaration of function set_vi_handler()
MIPS: Trap exception handling fixes
MIPS: Quit exposing Kconfig symbols in uapi headers.
MIPS: Remove duplicate definition of check_for_high_segbits.
cputime_to_timeval() takes a struct timeval *as its second argument but
a struct compat_timeval * will be passed resulting in:
CC arch/mips/kernel/binfmt_elfn32.o
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c: In function ‘fill_prstatus’:
arch/mips/kernel/../../../fs/binfmt_elf.c:1330:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1331:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1336:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1337:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1339:2: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1340:2: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
AS arch/mips/kernel/scall64-n32.o
CC arch/mips/kernel/signal_n32.o
CC arch/mips/kernel/binfmt_elfo32.o
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c: In function ‘fill_prstatus’:
arch/mips/kernel/../../../fs/binfmt_elf.c:1330:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1331:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1336:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1337:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1339:2: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1340:2: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
from include/linux/sched.h:28,
from include/linux/ptrace.h:5,
from include/uapi/linux/elfcore.h:7,
from include/linux/elfcore.h:7,
from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
As noted by Wladislav Wiebe:
$ halt
..
Sent SIGKILL to all processes
Requesting system halt
[66.729373] System halted.
[66.733244]
[66.734761] =====================================
[66.739473] [ BUG: lock held at task exit time! ]
[66.744188] 3.8.7-0-sampleversion-fct #49 Tainted: G O
[66.750202] -------------------------------------
[66.754913] init/21479 is exiting with locks still held!
[66.760234] 1 lock held by init/21479:
[66.763990] #0: (reboot_mutex){+.+...}, at: [<ffffffff801776c8>] SyS_reboot+0xe0/0x218
[66.772165]
[66.772165] stack backtrace:
[66.776532] Call Trace:
[66.778992] [<ffffffff805780a8>] dump_stack+0x8/0x34
[66.783972] [<ffffffff801618b0>] do_exit+0x610/0xa70
[66.788948] [<ffffffff801777a8>] SyS_reboot+0x1c0/0x218
[66.794186] [<ffffffff8013d6a4>] handle_sys64+0x44/0x64
This is an alternative fix to the one sent by Wladislav. We kill the
watchdog for each CPU and then spin in WAIT with interrupts disabled.
This is the lowest power mode for the OCTEON. If we were to spin with
interrupts enabled, we would get a continual stream of warning messages
and backtraces from the lockup detector, so I chose to disable
interrupts.
Signed-off-by: David Daney <david.daney@cavium.com>
Cc: Maxim Uvarov <muvarov@gmail.com>
Cc: Wladislav Wiebe <wladislav.kw@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: David Daney <david.daney@cavium.com>
Patchwork: https://patchwork.linux-mips.org/patch/5324/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The Linux Way is to return -ENOIOCTLCMD to the vfs when an
unimplemented ioctl is requested. Do this in kvm_mips instead of a
random mixture of -ENOTSUPP and -EINVAL.
Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: Sanjay Lal <sanjayl@kymasys.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Because not all 256 CP0 registers are ever implemented, we need a
different method of manipulating them. Use the
KVM_SET_ONE_REG/KVM_GET_ONE_REG mechanism.
Now unused code and definitions are removed.
Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: Sanjay Lal <sanjayl@kymasys.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
All registers are 64-bits wide, 32-bit guests use the least
significant portion of the register storage fields.
Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: Sanjay Lal <sanjayl@kymasys.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull USB fixes from Greg Kroah-Hartman:
"Here are a number of tiny USB bugfixes / new device ids for 3.10-rc2
The majority of these are USB gadget fixes, but they are all small.
Other than that, some USB host controller fixes, and USB serial driver
fixes for problems reported with them.
Also hopefully a fixed up USB_OTG Kconfig dependancy, that one seems
to be almost impossible to get right for all of the different
platforms these days."
* tag 'usb-3.10-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (56 commits)
USB: cxacru: potential underflow in cxacru_cm_get_array()
USB: ftdi_sio: Add support for Newport CONEX motor drivers
USB: option: add device IDs for Dell 5804 (Novatel E371) WWAN card
usb: ohci: fix goto wrong tag in err case
usb: isp1760-if: fix memleak when platform_get_resource fail
usb: ehci-s5p: fix memleak when fallback to pdata
USB: serial: clean up chars_in_buffer
USB: ti_usb_3410_5052: fix chars_in_buffer overhead
USB: io_ti: fix chars_in_buffer overhead
USB: ftdi_sio: fix chars_in_buffer overhead
USB: ftdi_sio: clean up get_modem_status
USB: serial: add generic wait_until_sent implementation
USB: serial: add wait_until_sent operation
USB: set device dma_mask without reference to global data
USB: Blacklisted Cinterion's PLxx WWAN Interface
usb: option: Add Telewell TW-LTE 4G
USB: EHCI: remove bogus #error
USB: reset resume quirk needed by a hub
USB: usb-stor: realtek_cr: Fix compile error
usb, chipidea: fix link error when USB_EHCI_HCD is a module
...
Pull kvm bugfixes from Gleb Natapov.
* git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM/MIPS32: Wrap calls to gfn_to_pfn() with srcu_read_lock/unlock()
KVM/MIPS32: Move include/asm/kvm.h => include/uapi/asm/kvm.h since it is a user visible API.
KVM: take over co-maintainership from Marcelo, fix MAINTAINERS entry
The kernel's struct pt_regs has many fields conditional on various
Kconfig variables, we cannot be exporting this garbage to user-space.
Move the kernel's definition to asm/ptrace.h, and put a uapi only
version in uapi/asm/ptrace.h gated by #ifndef __KERNEL__
Signed-off-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5305/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
