1. 21 Sep, 2015 9 commits
  2. 14 Sep, 2015 8 commits
  3. 12 Sep, 2015 13 commits
    • Linus Torvalds's avatar
      Linux 4.3-rc1 · 6ff33f39
      Linus Torvalds authored
      6ff33f39
    • Linus Torvalds's avatar
      Merge tag 'cris-for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/jesper/cris · 6917b51d
      Linus Torvalds authored
      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
        ...
      6917b51d
    • Linus Torvalds's avatar
      blk: rq_data_dir() should not return a boolean · 10fbd36e
      Linus Torvalds authored
      rq_data_dir() returns either READ or WRITE (0 == READ, 1 == WRITE), not
      a boolean value.
      
      Now, admittedly the "!= 0" doesn't really change the value (0 stays as
      zero, 1 stays as one), but it's not only redundant, it confuses gcc, and
      causes gcc to warn about the construct
      
          switch (rq_data_dir(req)) {
              case READ:
                  ...
              case WRITE:
                  ...
      
      that we have in a few drivers.
      
      Now, the gcc warning is silly and stupid (it seems to warn not about the
      switch value having a different type from the case statements, but about
      _any_ boolean switch value), but in this case the code itself is silly
      and stupid too, so let's just change it, and get rid of warnings like
      this:
      
        drivers/block/hd.c: In function ‘hd_request’:
        drivers/block/hd.c:630:11: warning: switch condition has boolean value [-Wswitch-bool]
           switch (rq_data_dir(req)) {
      
      The odd '!= 0' came in when "cmd_flags" got turned into a "u64" in
      commit 5953316d ("block: make rq->cmd_flags be 64-bit") and is
      presumably because the old code (that just did a logical 'and' with 1)
      would then end up making the type of rq_data_dir() be u64 too.
      
      But if we want to retain the old regular integer type, let's just cast
      the result to 'int' rather than use that rather odd '!= 0'.
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      10fbd36e
    • Linus Torvalds's avatar
      Merge branch 'writeback-plugging' · e1df8b0a
      Linus Torvalds authored
      Fix up the writeback plugging introduced in commit d353d758
      ("writeback: plug writeback at a high level") that then caused problems
      due to the unplug happening with a spinlock held.
      
      * writeback-plugging:
        writeback: plug writeback in wb_writeback() and writeback_inodes_wb()
        Revert "writeback: plug writeback at a high level"
      e1df8b0a
    • Linus Torvalds's avatar
      writeback: plug writeback in wb_writeback() and writeback_inodes_wb() · 505a666e
      Linus Torvalds authored
      We had to revert the pluggin in writeback_sb_inodes() because the
      wb->list_lock is held, but we could easily plug at a higher level before
      taking that lock, and unplug after releasing it.  This does that.
      
      Chris will run performance numbers, just to verify that this approach is
      comparable to the alternative (we could just drop and re-take the lock
      around the blk_finish_plug() rather than these two commits.
      
      I'd have preferred waiting for actual performance numbers before picking
      one approach over the other, but I don't want to release rc1 with the
      known "sleeping function called from invalid context" issue, so I'll
      pick this cleanup version for now.  But if the numbers show that we
      really want to plug just at the writeback_sb_inodes() level, and we
      should just play ugly games with the spinlock, we'll switch to that.
      
      Cc: Chris Mason <clm@fb.com>
      Cc: Josef Bacik <jbacik@fb.com>
      Cc: Dave Chinner <david@fromorbit.com>
      Cc: Neil Brown <neilb@suse.de>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Christoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      505a666e
    • Linus Torvalds's avatar
      thermal: fix intel PCH thermal driver mismerge · dfb22fc5
      Linus Torvalds authored
      I didn't notice this when merging the thermal code from Zhang, but his
      merge (commit 5a924a07: "Merge branches 'thermal-core' and
      'thermal-intel' of .git into next") of the thermal-core and
      thermal-intel branches was wrong.
      
      In thermal-core, commit 17e8351a ("thermal: consistently use int for
      temperatures") converted the thermal layer to use "int" for
      temperatures.
      
      But in parallel, in the thermal-intel branch commit d0a12625
      ("thermal: Add Intel PCH thermal driver") added support for the intel
      PCH thermal sensor using the old interfaces that used "unsigned long"
      pointers.
      
      This resulted in warnings like this:
      
        drivers/thermal/intel_pch_thermal.c:184:14: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
          .get_temp = pch_thermal_get_temp,
                      ^
        drivers/thermal/intel_pch_thermal.c:184:14: note: (near initialization for ‘tzd_ops.get_temp’)
        drivers/thermal/intel_pch_thermal.c:186:19: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
          .get_trip_temp = pch_get_trip_temp,
                           ^
        drivers/thermal/intel_pch_thermal.c:186:19: note: (near initialization for ‘tzd_ops.get_trip_temp’)
      
      This fixes it.
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      dfb22fc5
    • Linus Torvalds's avatar
      Merge branch 'akpm' (patches from Andrew) · 01b0c014
      Linus Torvalds authored
      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
      01b0c014
    • Vineet Gupta's avatar
      ARCv2: [axs103_smp] Reduce clk for SMP FPGA configs · 3ebb0540
      Vineet Gupta authored
      Newer bitfiles needs the reduced clk even for SMP builds
      
      Cc: <stable@vger.kernel.org>  #4.2
      Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3ebb0540
    • Linus Torvalds's avatar
      Merge tag 'ntb-4.3' of git://github.com/jonmason/ntb · ded0e250
      Linus Torvalds authored
      Pull NTB fixes from Jon Mason:
       "NTB bug and documentation fixes, new device IDs, performance
        improvements, and adding a mailing list to MAINTAINERS for NTB"
      
      * tag 'ntb-4.3' of git://github.com/jonmason/ntb:
        NTB: Fix range check on memory window index
        NTB: Improve index handling in B2B MW workaround
        NTB: Fix documentation for ntb_peer_db_clear.
        NTB: Fix documentation for ntb_link_is_up
        NTB: Use unique DMA channels for TX and RX
        NTB: Remove dma_sync_wait from ntb_async_rx
        NTB: Clean up QP stats info
        NTB: Make the transport list in order of discovery
        NTB: Add PCI Device IDs for Broadwell Xeon
        NTB: Add flow control to the ntb_netdev
        NTB: Add list to MAINTAINERS
      ded0e250
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input · f0c032d8
      Linus Torvalds authored
      Pull more input updates from Dmitry Torokhov:
       "Second round of updates for the input subsystem.
      
        This introduces two brand new touchscreen drivers (Colibri and
        imx6ul_tsc), some small driver fixes, and we are no longer report
        errors from evdev_flush() as users do not really have a way of
        handling errors, error codes that we were returning were not on the
        list of errors supposed to be returned by close(), and errors were
        causing issues with one of older versions of systemd"
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
        Input: imx_keypad - remove obsolete comment
        Input: touchscreen - add imx6ul_tsc driver support
        Input: Add touchscreen support for Colibri VF50
        Input: i8042 - lower log level for "no controller" message
        Input: evdev - do not report errors form flush()
        Input: elants_i2c - extend the calibration timeout to 12 seconds
        Input: sparcspkr - fix module autoload for OF platform drivers
        Input: regulator-haptic - fix module autoload for OF platform driver
        Input: pwm-beeper - fix module autoload for OF platform driver
        Input: ab8500-ponkey - Fix module autoload for OF platform driver
        Input: cyttsp - remove unnecessary MODULE_ALIAS()
        Input: elan_i2c - add ACPI ID "ELAN1000"
      f0c032d8
    • Linus Torvalds's avatar
      Merge tag 'pm+acpi-4.3-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm · fa9a67ef
      Linus Torvalds authored
      Pull more power management and ACPI updates from Rafael Wysocki:
       "These are mostly fixes and cleanups on top of the previous PM+ACPI
        pull request (cpufreq core and drivers, cpuidle, generic power domains
        framework).  Some of them didn't make to that pull request and some
        fix issues introduced by it.
      
        The only really new thing is the support for suspend frequency in the
        cpufreq-dt driver, but it is needed to fix an issue with Exynos
        platforms.
      
        Specifics:
      
         - build fix for the new Mediatek MT8173 cpufreq driver (Guenter
           Roeck).
      
         - generic power domains framework fixes (power on error code path,
           subdomain removal) and cleanup of a deprecated API user (Geert
           Uytterhoeven, Jon Hunter, Ulf Hansson).
      
         - cpufreq-dt driver fixes including two fixes for bugs related to the
           new Operating Performance Points Device Tree bindings introduced
           recently (Viresh Kumar).
      
         - suspend frequency support for the cpufreq-dt driver (Bartlomiej
           Zolnierkiewicz, Viresh Kumar).
      
         - cpufreq core cleanups (Viresh Kumar).
      
         - intel_pstate driver fixes (Chen Yu, Kristen Carlson Accardi).
      
         - additional sanity check in the cpuidle core (Xunlei Pang).
      
         - fix for a comment related to CPU power management (Lina Iyer)"
      
      * tag 'pm+acpi-4.3-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
        intel_pstate: fix PCT_TO_HWP macro
        intel_pstate: Fix user input of min/max to legal policy region
        PM / OPP: Return suspend_opp only if it is enabled
        cpufreq-dt: add suspend frequency support
        cpufreq: allow cpufreq_generic_suspend() to work without suspend frequency
        PM / OPP: add dev_pm_opp_get_suspend_opp() helper
        staging: board: Migrate away from __pm_genpd_name_add_device()
        cpufreq: Use __func__ to print function's name
        cpufreq: staticize cpufreq_cpu_get_raw()
        PM / Domains: Ensure subdomain is not in use before removing
        cpufreq: Add ARM_MT8173_CPUFREQ dependency on THERMAL
        cpuidle/coupled: Add sanity check for safe_state_index
        PM / Domains: Try power off masters in error path of __pm_genpd_poweron()
        cpufreq: dt: Tolerance applies on both sides of target voltage
        cpufreq: dt: Print error on failing to mark OPPs as shared
        cpufreq: dt: Check OPP count before marking them shared
        kernel/cpu_pm: fix cpu_cluster_pm_exit comment
      fa9a67ef
    • Linus Torvalds's avatar
      Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending · 05c78081
      Linus Torvalds authored
      Pull SCSI target updates from Nicholas Bellinger:
       "Here are the outstanding target-pending updates for v4.3-rc1.
      
        Mostly bug-fixes and minor changes this round.  The fallout from the
        big v4.2-rc1 RCU conversion have (thus far) been minimal.
      
        The highlights this round include:
      
         - Move sense handling routines into scsi_common code (Sagi)
      
         - Return ABORTED_COMMAND sense key for PI errors (Sagi)
      
         - Add tpg_enabled_sendtargets attribute for disabled iscsi-target
           discovery (David)
      
         - Shrink target struct se_cmd by rearranging fields (Roland)
      
         - Drop iSCSI use of mutex around max_cmd_sn increment (Roland)
      
         - Replace iSCSI __kernel_sockaddr_storage with sockaddr_storage (Andy +
           Chris)
      
         - Honor fabric max_data_sg_nents I/O transfer limit (Arun + Himanshu +
           nab)
      
         - Fix EXTENDED_COPY >= v4.1 regression OOPsen (Alex + nab)"
      
      * 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (37 commits)
        target: use stringify.h instead of own definition
        target/user: Fix UFLAG_UNKNOWN_OP handling
        target: Remove no-op conditional
        target/user: Remove unused variable
        target: Fix max_cmd_sn increment w/o cmdsn mutex regressions
        target: Attach EXTENDED_COPY local I/O descriptors to xcopy_pt_sess
        target/qla2xxx: Honor max_data_sg_nents I/O transfer limit
        target/iscsi: Replace __kernel_sockaddr_storage with sockaddr_storage
        target/iscsi: Replace conn->login_ip with login_sockaddr
        target/iscsi: Keep local_ip as the actual sockaddr
        target/iscsi: Fix np_ip bracket issue by removing np_ip
        target: Drop iSCSI use of mutex around max_cmd_sn increment
        qla2xxx: Update tcm_qla2xxx module description to 24xx+
        iscsi-target: Add tpg_enabled_sendtargets for disabled discovery
        drivers: target: Drop unlikely before IS_ERR(_OR_NULL)
        target: check DPO/FUA usage for COMPARE AND WRITE
        target: Shrink struct se_cmd by rearranging fields
        target: Remove cmd->se_ordered_id (unused except debug log lines)
        target: add support for START_STOP_UNIT SCSI opcode
        target: improve unsupported opcode message
        ...
      05c78081
    • Linus Torvalds's avatar
      Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi · 8e78b7dc
      Linus Torvalds authored
      Pull second round of SCSI updates from James Bottomley:
       "There's one late arriving patch here (added today), fixing a build
        issue which the scsi_dh patch set in here uncovered.  Other than that,
        everything has been incubated in -next and the checkers for a week.
      
        The major pieces of this patch are a set patches facilitating better
        integration between scsi and scsi_dh (the device handling layer used
        by multi-path; all the dm parts are acked by Mike Snitzer).
      
        This also includes driver updates for mp3sas, scsi_debug and an
        assortment of bug fixes"
      
      * tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (50 commits)
        scsi_dh: fix randconfig build error
        scsi: fix scsi_error_handler vs. scsi_host_dev_release race
        fcoe: Convert use of __constant_htons to htons
        mpt2sas: setpci reset kernel oops fix
        pm80xx: Don't override ts->stat on IO_OPEN_CNX_ERROR_HW_RESOURCE_BUSY
        lpfc: Fix possible use-after-free and double free in lpfc_mbx_cmpl_rdp_page_a2()
        bfa: Fix incorrect de-reference of pointer
        bfa: Fix indentation
        scsi_transport_sas: Remove check for SAS expander when querying bay/enclosure IDs.
        scsi_debug: resp_request: remove unused variable
        scsi_debug: fix REPORT LUNS Well Known LU
        scsi_debug: schedule_resp fix input variable check
        scsi_debug: make dump_sector static
        scsi_debug: vfree is null safe so drop the check
        scsi_debug: use SCSI_W_LUN_REPORT_LUNS instead of SAM2_WLUN_REPORT_LUNS;
        scsi_debug: define pr_fmt() for consistent logging
        mpt2sas: Refcount fw_events and fix unsafe list usage
        mpt2sas: Refcount sas_device objects and fix unsafe list usage
        scsi_dh: return SCSI_DH_NOTCONN in scsi_dh_activate()
        scsi_dh: don't allow to detach device handlers at runtime
        ...
      8e78b7dc
  4. 11 Sep, 2015 10 commits
    • Linus Torvalds's avatar
      Merge tag 'media/v4.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media · 06a660ad
      Linus Torvalds authored
      Pull media updates from Mauro Carvalho Chehab:
       "A series of patches that move part of the code used to allocate memory
        from the media subsystem to the mm subsystem"
      
      [ The mm parts have been acked by VM people, and the series was
        apparently in -mm for a while   - Linus ]
      
      * tag 'media/v4.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
        [media] drm/exynos: Convert g2d_userptr_get_dma_addr() to use get_vaddr_frames()
        [media] media: vb2: Remove unused functions
        [media] media: vb2: Convert vb2_dc_get_userptr() to use frame vector
        [media] media: vb2: Convert vb2_vmalloc_get_userptr() to use frame vector
        [media] media: vb2: Convert vb2_dma_sg_get_userptr() to use frame vector
        [media] vb2: Provide helpers for mapping virtual addresses
        [media] media: omap_vout: Convert omap_vout_uservirt_to_phys() to use get_vaddr_pfns()
        [media] mm: Provide new get_vaddr_frames() helper
        [media] vb2: Push mmap_sem down to memops
      06a660ad
    • Linus Torvalds's avatar
      Merge tag 'edac/v4.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-edac · d9b44fe3
      Linus Torvalds authored
      Pull edac updates from Mauro Carvalho Chehab:
       "Two EDAC fixes for Intel systems (Haswell and Ivy Bridge)"
      
      * tag 'edac/v4.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-edac:
        sb_edac: correctly fetch DIMM width on Ivy Bridge and Haswell
        sb_edac: look harder for DDRIO on Haswell systems
      d9b44fe3
    • Linus Torvalds's avatar
      Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux · 9ebd051a
      Linus Torvalds authored
      Pull thermal updates from Zhang Rui:
      
       - use int instead of unsigned long to represent temperature to avoid
         bogus overheat detection when negative temperature reported.  From
         Sascha Hauer.
      
       - export available thermal governors information to user space via
         sysfs.  From Wei Ni.
      
       - introduce new thermal driver for Wildcat Point platform controller
         hub, which uses PCH thermal sensor and associated critical and hot
         trip points.  From Tushar Dave.
      
       - add suuport for Intel Skylake and Denlow platforms in powerclamp
         driver.
      
       - some small cleanups in thermal core.
      
      * 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux:
        thermal: Add Intel PCH thermal driver
        thermal: Add comment explaining test for critical temperature
        thermal: Use IS_ENABLED instead of #ifdef
        thermal: remove unnecessary call to thermal_zone_device_set_polling
        thermal: trivial: fix typo in comment
        thermal: consistently use int for temperatures
        thermal: add available policies sysfs attribute
        thermal/powerclamp: add cpu id for denlow platform
        thermal/powerclamp: add cpu id for Skylake u/y
        thermal/powerclamp: add cpu id for skylake h/s
      9ebd051a
    • Andrew Morton's avatar
      revert "ocfs2/dlm: use list_for_each_entry instead of list_for_each" · e527b22c
      Andrew Morton authored
      Revert commit f83c7b5e ("ocfs2/dlm: use list_for_each_entry instead
      of list_for_each").
      
      list_for_each_entry() will dereference its `pos' argument, which can be
      NULL in dlm_process_recovery_data().
      Reported-by: default avatarJulia Lawall <julia.lawall@lip6.fr>
      Reported-by: default avatarFengguang Wu <fengguang.wu@gmail.com>
      Cc: Joseph Qi <joseph.qi@huawei.com>
      Cc: Mark Fasheh <mfasheh@suse.de>
      Cc: Joel Becker <jlbec@evilplan.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e527b22c
    • Ard Biesheuvel's avatar
      mm/early_ioremap: add explicit #include of asm/early_ioremap.h · 4f1af60b
      Ard Biesheuvel authored
      Commit 6b0f68e3 ("mm: add utility for early copy from unmapped ram")
      introduces a function copy_from_early_mem() into mm/early_ioremap.c
      which itself calls early_memremap()/early_memunmap().  However, since
      early_memunmap() has not been declared yet at this point in the .c file,
      nor by any explicitly included header files, we are depending on a
      transitive include of asm/early_ioremap.h to declare it, which is
      fragile.
      
      So instead, include this header explicitly.
      Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
      Acked-by: default avatarMark Salter <msalter@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      4f1af60b
    • Joe Perches's avatar
      fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to void · 6798a8ca
      Joe Perches authored
      The seq_<foo> function return values were frequently misused.
      
      See: commit 1f33c41c ("seq_file: Rename seq_overflow() to
           seq_has_overflowed() and make public")
      
      All uses of these return values have been removed, so convert the
      return types to void.
      
      Miscellanea:
      
      o Move seq_put_decimal_<type> and seq_escape prototypes closer the
        other seq_vprintf prototypes
      o Reorder seq_putc and seq_puts to return early on overflow
      o Add argument names to seq_vprintf and seq_printf
      o Update the seq_escape kernel-doc
      o Convert a couple of leading spaces to tabs in seq_escape
      Signed-off-by: default avatarJoe Perches <joe@perches.com>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Mark Brown <broonie@kernel.org>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: Joerg Roedel <jroedel@suse.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6798a8ca
    • Mathieu Desnoyers's avatar
      selftests: enhance membarrier syscall test · c9946c42
      Mathieu Desnoyers authored
      Update the membarrier syscall self-test to match the membarrier
      interface.  Extend coverage of the interface.  Consider ENOSYS as a
      "SKIP" test, since it is a valid configuration, but does not allow
      testing the system call.
      Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Cc: Pranith Kumar <bobby.prani@gmail.com>
      Cc: Shuah Khan <shuahkh@osg.samsung.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c9946c42
    • Pranith Kumar's avatar
      selftests: add membarrier syscall test · b6d97344
      Pranith Kumar authored
      Add a self test for the membarrier system call.
      Signed-off-by: default avatarPranith Kumar <bobby.prani@gmail.com>
      Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Cc: Shuah Khan <shuahkh@osg.samsung.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b6d97344
    • Mathieu Desnoyers's avatar
      sys_membarrier(): system-wide memory barrier (generic, x86) · 5b25b13a
      Mathieu Desnoyers authored
      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: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Reviewed-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Reviewed-by: default avatarJosh 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: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5b25b13a
    • David Howells's avatar
      MODSIGN: fix a compilation warning in extract-cert · 7c0d35a3
      David Howells authored
      Fix the following warning when compiling extract-cert:
      
        scripts/extract-cert.c: In function `write_cert':
        scripts/extract-cert.c:89:2: warning: format not a string literal and no format arguments [-Wformat-security]
          ERR(!i2d_X509_bio(wb, x509), cert_dst);
          ^
      
      whereby the ERR() macro is taking cert_dst as the format string.  "%s"
      should be used as the format string as the path could contain special
      characters.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Reported-by: default avatarJim Davis <jim.epost@gmail.com>
      Acked-by : David Woodhouse <david.woodhouse@intel.com>
      Cc: James Morris <jmorris@namei.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7c0d35a3