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2015-10-07ARM: shmobile: porter: add SDHI0/2 DT supportSergei Shtylyov
Define the Porter board dependent part of the SDHI0/2 device nodes along with the necessary voltage regulators (note that the Vcc regulators are dummy -- they are required but don't actually exist on the board). Also, GPIOs have to be used for the CD and WP signals due to the SDHI driver constraints... This patch is analogous to the commit 1299df03d719 ("ARM: shmobile: henninger: add SDHI0/2 DT support") as there are no differences between those boards in this respect. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-10-06ARM: shmobile: porter: add Ether DT supportSergei Shtylyov
Define the Porter board dependent part of the Ether device node. Enable DHCP and NFS root for the kernel booting. This patch is analogous to the commit 26b0d2cf73cb ("ARM: shmobile: henninger: add Ether DT support") as there are no differences between those boards in this respect. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-10-05ARM: shmobile: r8a7794: add HS-USB DT supportSergei Shtylyov
Define the R8A7794 generic part of the HS-USB device node. It is up to the board file to enable the device. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-10-02ARM: shmobile: dts: Add common file for AA121TD01 panelKuninori Morimoto
The Mitsubishi AA121TD01 panel is commonly used with the Marzen, Lager and Koelsch boards. Create a .dtsi file that describe the panel and its connection to the board. Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-10-02ARM: shmobile: r8a7794: link PCI USB devices to USB PHYSergei Shtylyov
Describe the PCI USB devices that are behind the PCI bridges, adding necessary links to the USB PHY device. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-10-02ARM: shmobile: silk: enable USB PHYSergei Shtylyov
Enable USB PHY device for the SILK board. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-10-02ARM: shmobile: r8a7794: add USB PHY DT supportSergei Shtylyov
Define the R8A7794 generic part of the USB PHY device node. It is up to the board file to enable the device. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-10-02ARM: shmobile: porter: initial device treeSergei Shtylyov
Add the initial device tree for the R8A7791 SoC based Porter low cost board (which is a slightly modified version of the Henninger board). SCIF0 serial port support is included, so that the serial console can work. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-30ARM: shmobile: silk: enable internal PCISergei Shtylyov
Enable internal AHB-PCI bridges for the USB EHCI/OHCI controllers attached to them. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-30ARM: shmobile: r8a7794: add internal PCI bridge nodesSergei Shtylyov
Add device nodes for the R8A7794 internal PCI bridge devices. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: r8a7790: lager: add pinmux for iic0Wolfram Sang
It seems we used to rely on the default pinmux setting of this HW, but currently we need to explicitly set the pinmux to access this bus. It is better style, too. Signed-off-by: Wolfram Sang <wsa@sang-engineering.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: r8a7778: tidyup SSI resource regionKuninori Morimoto
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: r8a7791: tidyup SSI resource regionKuninori Morimoto
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: r8a7790: tidyup SSI resource regionKuninori Morimoto
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: lager: use CCF for audio clockKuninori Morimoto
Because of historical reason, audio clock didn't use CCF. Let's use it now. Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: koelsch: use CCF for audio clockKuninori Morimoto
Because of historical reason, audio clock didn't use CCF. Let's use it now. Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: silk: add VIN0/ADV7180 DT supportSergei Shtylyov
Define the SILK board dependent part of the VIN0 device node. Add the device node for Analog Devices ADV7180 video decoder to I2C1 bus. Add the necessary subnodes to interconnect VIN0 and ADV7180 devices. Based on the Henninger VIN0/ADV8170 device tree patch by myself. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: r8a7794: add VIN DT supportSergei Shtylyov
Define the generic R8A7794 part of the VIN[01] device nodes. Add aliases for the VIN[01] device nodes. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: silk: add I2C1 DT supportSergei Shtylyov
Define the SILK board dependent part of the I2C1 device node. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: r8a7794: add I2C DT supportSergei Shtylyov
Define the generic R8A7794 parts of the I2C[0-5] device nodes. Based on the original patch by Koji Matsuoka <koji.matsuoka.xm@renesas.com>. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: kzm9g dts: Use adxl345-specific compatible propertyGeert Uytterhoeven
Replace the deprecated generic "adi,adxl34x" compatible value by the adxl345-specific "adi,adxl345" value, cfr. commit e465bf6fc55d5ce2 ("DT: i2c: Deprecate adi,adxl34x compatible string"). Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Acked-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: marzen: Board specific serial port orderMagnus Damm
Convert Marzen to use board-specific serial0 and serial1 instead of the older shared SoC-specific SCIF index. Signed-off-by: Magnus Damm <damm+renesas@opensource.se> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Acked-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: silk: add QSPI DT supportSergei Shtylyov
Define the SILK board dependent part of the QSPI device node. Add device nodes for Spansion S25FL512S SPI flash and MTD partitions on it. Based on the original patch by Vladimir Barinov <vladimir.barinov@cogentembedded.com>. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: r8a7794: add QSPI DT supportSergei Shtylyov
Define the generic R8A7794 part of the QSPI device node. Based on original patch by Hisashi Nakamura <hisashi.nakamura.ak@renesas.com>. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: r8a7794: add GPIO DT supportSergei Shtylyov
Describe GPIO[0-6] controllers in the R8A7794 device tree. Based on original patch by Hisashi Nakamura <hisashi.nakamura.ak@renesas.com>. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: r8a7794: add GPIO clocksSergei Shtylyov
Describe the GPIO clocks in the R8A7794 device tree. Based on the original patch by Koji Matsuoka <koji.matsuoka.xm@renesas.com>. Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: Remove legacy clock support leftoversLaurent Pinchart
The shmobile_clk_init() function has been removed and the linux/sh_clk.h header doesn't need to be included anymore. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: remove Makefile.bootSimon Horman
Now that the only multiplatform boot is supported for all shmobile platforms Makefile.boot may be removed. This seems correct to me given: * Setting MACHINE to no value in arch/arm/Makefile if CONFIG_ARCH_MULTIPLATFORM is set * Not including Makefile.boot in arch/arm/boot/Makefile if MACHINE has no value Signed-off-by: Simon Horman <horms+renesas@verge.net.au> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
2015-09-14ARM: shmobile: Kconfig: remove unused SHMOBILE_TIMER_HZ sectionUlrich Hecht
Obsoleted by removal of legacy platforms. Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: bockw: remove legacy DTB build targetUlrich Hecht
Obsoleted by removal of legacy platform. Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: bockw: remove legacy defconfigUlrich Hecht
Obsoleted by removal of legacy platform. Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com> Acked-by: by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: remove ARCH_SHMOBILE_LEGACY optionUlrich Hecht
With Bock-W, the last legacy platform has been removed. Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com> Acked-by: by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: r8a7778: remove legacy clock implementationUlrich Hecht
Bock-W was the last legacy clock platform, so this also removes the common legacy clock code. Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com> Acked-by: by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: Kconfig: remove obsolete option ARCH_R8A7778Ulrich Hecht
Obsoleted by removal of r8a7778 legacy platform. Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com> Acked-by: by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: r8a7778: remove obsolete setup codeUlrich Hecht
Removal of the legacy Bock-W platform obsoletes most setup code. Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com> Acked-by: by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: bockw: remove legacy board file and configUlrich Hecht
Replaced by multi-platform. Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com> Acked-by: by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: bockw: remove "reference" board file and configUlrich Hecht
Replaced by multi-platform. Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: bockw: remove "reference" device treeUlrich Hecht
Replaced by multi-platform. Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: Remove obsolete twd_local_timer declarationGeert Uytterhoeven
The last user of twd_local_timer was removed in commit c99cd90d98a98aa1 ("ARM: shmobile: r8a7779: Remove legacy SoC code"). Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: Remove obsolete earlytimer registrationGeert Uytterhoeven
The last caller of shmobile_earlytimer_init() was removed in commit c99cd90d98a98aa1 ("ARM: shmobile: r8a7779: Remove legacy SoC code"). Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: Remove obsolete legacy PM Domain leftoversGeert Uytterhoeven
The last users were removed in commit b587288001f05c0e ("ARM: shmobile: R-Mobile: Remove legacy PM Domain code"). Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: Remove obsolete intc.hGeert Uytterhoeven
The last user of "intc.h" was removed in commit 9a9863987bf7307f ("ARM: shmobile: Remove legacy SoC code for SH-Mobile AG5"). Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: Remove obsolete custom earlyprintk codeGeert Uytterhoeven
The last caller of shmobile_setup_console() was removed in commit 44d88c754e57a6d9 ("ARM: shmobile: Remove legacy SoC code for R-Mobile A1"). Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: Remove obsolete sh-gpio.hGeert Uytterhoeven
The last user of "sh-gpio.h" was removed in commit 1fa59bda21c7fa36 ("ARM: shmobile: Remove legacy board code for Armadillo-800 EVA"). Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-14ARM: shmobile: Remove unused declaration of r8a7778_add_standard_devices_dt()Geert Uytterhoeven
The actual implementation was removed by commit 40216263d3d0b9b4 ("ARM: shmobile: Remove unused r8a7778 auxdata and callback") in v3.12. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2015-09-12Merge tag 'cris-for-4.3' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jesper/cris Pull CRIS updates from Jesper Nilsson: "Mostly removal of old cruft of which we can use a generic version, or fixes for code not commonly run in the cris port, but also additions to enable some good debug" * tag 'cris-for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/jesper/cris: (25 commits) CRISv10: delete unused lib/dmacopy.c CRISv10: delete unused lib/old_checksum.c CRIS: fix switch_mm() lockdep splat CRISv32: enable LOCKDEP_SUPPORT CRIS: add STACKTRACE_SUPPORT CRISv32: annotate irq enable in idle loop CRISv32: add support for irqflags tracing CRIS: UAPI: use generic types.h CRIS: UAPI: use generic shmbuf.h CRIS: UAPI: use generic msgbuf.h CRIS: UAPI: use generic socket.h CRIS: UAPI: use generic sembuf.h CRIS: UAPI: use generic sockios.h CRIS: UAPI: use generic auxvec.h CRIS: UAPI: use generic headers via Kbuild CRIS: UAPI: fix elf.h export CRIS: don't make asm/elf.h depend on asm/user.h CRIS: UAPI: fix ptrace.h CRISv32: Squash compile warnings for axisflashmap CRISv32: Add GPIO driver to the default configs ...
2015-09-11Merge branch 'akpm' (patches from Andrew)Linus Torvalds
Merge fourth patch-bomb from Andrew Morton: - sys_membarier syscall - seq_file interface changes - a few misc fixups * emailed patches from Andrew Morton <akpm@linux-foundation.org>: revert "ocfs2/dlm: use list_for_each_entry instead of list_for_each" mm/early_ioremap: add explicit #include of asm/early_ioremap.h fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to void selftests: enhance membarrier syscall test selftests: add membarrier syscall test sys_membarrier(): system-wide memory barrier (generic, x86) MODSIGN: fix a compilation warning in extract-cert
2015-09-11ARCv2: [axs103_smp] Reduce clk for SMP FPGA configsVineet Gupta
Newer bitfiles needs the reduced clk even for SMP builds Cc: <stable@vger.kernel.org> #4.2 Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-11sys_membarrier(): system-wide memory barrier (generic, x86)Mathieu Desnoyers
Here is an implementation of a new system call, sys_membarrier(), which executes a memory barrier on all threads running on the system. It is implemented by calling synchronize_sched(). It can be used to distribute the cost of user-space memory barriers asymmetrically by transforming pairs of memory barriers into pairs consisting of sys_membarrier() and a compiler barrier. For synchronization primitives that distinguish between read-side and write-side (e.g. userspace RCU [1], rwlocks), the read-side can be accelerated significantly by moving the bulk of the memory barrier overhead to the write-side. The existing applications of which I am aware that would be improved by this system call are as follows: * Through Userspace RCU library (http://urcu.so) - DNS server (Knot DNS) https://www.knot-dns.cz/ - Network sniffer (http://netsniff-ng.org/) - Distributed object storage (https://sheepdog.github.io/sheepdog/) - User-space tracing (http://lttng.org) - Network storage system (https://www.gluster.org/) - Virtual routers (https://events.linuxfoundation.org/sites/events/files/slides/DPDK_RCU_0MQ.pdf) - Financial software (https://lkml.org/lkml/2015/3/23/189) Those projects use RCU in userspace to increase read-side speed and scalability compared to locking. Especially in the case of RCU used by libraries, sys_membarrier can speed up the read-side by moving the bulk of the memory barrier cost to synchronize_rcu(). * Direct users of sys_membarrier - core dotnet garbage collector (https://github.com/dotnet/coreclr/issues/198) Microsoft core dotnet GC developers are planning to use the mprotect() side-effect of issuing memory barriers through IPIs as a way to implement Windows FlushProcessWriteBuffers() on Linux. They are referring to sys_membarrier in their github thread, specifically stating that sys_membarrier() is what they are looking for. To explain the benefit of this scheme, let's introduce two example threads: Thread A (non-frequent, e.g. executing liburcu synchronize_rcu()) Thread B (frequent, e.g. executing liburcu rcu_read_lock()/rcu_read_unlock()) In a scheme where all smp_mb() in thread A are ordering memory accesses with respect to smp_mb() present in Thread B, we can change each smp_mb() within Thread A into calls to sys_membarrier() and each smp_mb() within Thread B into compiler barriers "barrier()". Before the change, we had, for each smp_mb() pairs: Thread A Thread B previous mem accesses previous mem accesses smp_mb() smp_mb() following mem accesses following mem accesses After the change, these pairs become: Thread A Thread B prev mem accesses prev mem accesses sys_membarrier() barrier() follow mem accesses follow mem accesses As we can see, there are two possible scenarios: either Thread B memory accesses do not happen concurrently with Thread A accesses (1), or they do (2). 1) Non-concurrent Thread A vs Thread B accesses: Thread A Thread B prev mem accesses sys_membarrier() follow mem accesses prev mem accesses barrier() follow mem accesses In this case, thread B accesses will be weakly ordered. This is OK, because at that point, thread A is not particularly interested in ordering them with respect to its own accesses. 2) Concurrent Thread A vs Thread B accesses Thread A Thread B prev mem accesses prev mem accesses sys_membarrier() barrier() follow mem accesses follow mem accesses In this case, thread B accesses, which are ensured to be in program order thanks to the compiler barrier, will be "upgraded" to full smp_mb() by synchronize_sched(). * Benchmarks On Intel Xeon E5405 (8 cores) (one thread is calling sys_membarrier, the other 7 threads are busy looping) 1000 non-expedited sys_membarrier calls in 33s =3D 33 milliseconds/call. * User-space user of this system call: Userspace RCU library Both the signal-based and the sys_membarrier userspace RCU schemes permit us to remove the memory barrier from the userspace RCU rcu_read_lock() and rcu_read_unlock() primitives, thus significantly accelerating them. These memory barriers are replaced by compiler barriers on the read-side, and all matching memory barriers on the write-side are turned into an invocation of a memory barrier on all active threads in the process. By letting the kernel perform this synchronization rather than dumbly sending a signal to every process threads (as we currently do), we diminish the number of unnecessary wake ups and only issue the memory barriers on active threads. Non-running threads do not need to execute such barrier anyway, because these are implied by the scheduler context switches. Results in liburcu: Operations in 10s, 6 readers, 2 writers: memory barriers in reader: 1701557485 reads, 2202847 writes signal-based scheme: 9830061167 reads, 6700 writes sys_membarrier: 9952759104 reads, 425 writes sys_membarrier (dyn. check): 7970328887 reads, 425 writes The dynamic sys_membarrier availability check adds some overhead to the read-side compared to the signal-based scheme, but besides that, sys_membarrier slightly outperforms the signal-based scheme. However, this non-expedited sys_membarrier implementation has a much slower grace period than signal and memory barrier schemes. Besides diminishing the number of wake-ups, one major advantage of the membarrier system call over the signal-based scheme is that it does not need to reserve a signal. This plays much more nicely with libraries, and with processes injected into for tracing purposes, for which we cannot expect that signals will be unused by the application. An expedited version of this system call can be added later on to speed up the grace period. Its implementation will likely depend on reading the cpu_curr()->mm without holding each CPU's rq lock. This patch adds the system call to x86 and to asm-generic. [1] http://urcu.so membarrier(2) man page: MEMBARRIER(2) Linux Programmer's Manual MEMBARRIER(2) NAME membarrier - issue memory barriers on a set of threads SYNOPSIS #include <linux/membarrier.h> int membarrier(int cmd, int flags); DESCRIPTION The cmd argument is one of the following: MEMBARRIER_CMD_QUERY Query the set of supported commands. It returns a bitmask of supported commands. MEMBARRIER_CMD_SHARED Execute a memory barrier on all threads running on the system. Upon return from system call, the caller thread is ensured that all running threads have passed through a state where all memory accesses to user-space addresses match program order between entry to and return from the system call (non-running threads are de facto in such a state). This covers threads from all pro=E2=80=90 cesses running on the system. This command returns 0. The flags argument needs to be 0. For future extensions. All memory accesses performed in program order from each targeted thread is guaranteed to be ordered with respect to sys_membarrier(). If we use the semantic "barrier()" to represent a compiler barrier forcing memory accesses to be performed in program order across the barrier, and smp_mb() to represent explicit memory barriers forcing full memory ordering across the barrier, we have the following ordering table for each pair of barrier(), sys_membarrier() and smp_mb(): The pair ordering is detailed as (O: ordered, X: not ordered): barrier() smp_mb() sys_membarrier() barrier() X X O smp_mb() X O O sys_membarrier() O O O RETURN VALUE On success, these system calls return zero. On error, -1 is returned, and errno is set appropriately. For a given command, with flags argument set to 0, this system call is guaranteed to always return the same value until reboot. ERRORS ENOSYS System call is not implemented. EINVAL Invalid arguments. Linux 2015-04-15 MEMBARRIER(2) Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Nicholas Miell <nmiell@comcast.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Stephen Hemminger <stephen@networkplumber.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: David Howells <dhowells@redhat.com> Cc: Pranith Kumar <bobby.prani@gmail.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Shuah Khan <shuahkh@osg.samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-10Merge branch 'akpm' (patches from Andrew)Linus Torvalds
Merge third patch-bomb from Andrew Morton: - even more of the rest of MM - lib/ updates - checkpatch updates - small changes to a few scruffy filesystems - kmod fixes/cleanups - kexec updates - a dma-mapping cleanup series from hch * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (81 commits) dma-mapping: consolidate dma_set_mask dma-mapping: consolidate dma_supported dma-mapping: cosolidate dma_mapping_error dma-mapping: consolidate dma_{alloc,free}_noncoherent dma-mapping: consolidate dma_{alloc,free}_{attrs,coherent} mm: use vma_is_anonymous() in create_huge_pmd() and wp_huge_pmd() mm: make sure all file VMAs have ->vm_ops set mm, mpx: add "vm_flags_t vm_flags" arg to do_mmap_pgoff() mm: mark most vm_operations_struct const namei: fix warning while make xmldocs caused by namei.c ipc: convert invalid scenarios to use WARN_ON zlib_deflate/deftree: remove bi_reverse() lib/decompress_unlzma: Do a NULL check for pointer lib/decompressors: use real out buf size for gunzip with kernel fs/affs: make root lookup from blkdev logical size sysctl: fix int -> unsigned long assignments in INT_MIN case kexec: export KERNEL_IMAGE_SIZE to vmcoreinfo kexec: align crash_notes allocation to make it be inside one physical page kexec: remove unnecessary test in kimage_alloc_crash_control_pages() kexec: split kexec_load syscall from kexec core code ...