1. 15 Aug, 2018 1 commit
  2. 29 Aug, 2017 3 commits
  3. 20 Apr, 2017 2 commits
  4. 05 Jan, 2017 1 commit
    • Daniel Bristot de Oliveira's avatar
      x86/irq, trace: Add __irq_entry annotation to x86's platform IRQ handlers · c4158ff5
      Daniel Bristot de Oliveira authored
      
      
      This patch adds the __irq_entry annotation to the default x86
      platform IRQ handlers. ftrace's function_graph tracer uses the
      __irq_entry annotation to notify the entry and return of IRQ
      handlers.
      
      For example, before the patch:
        354549.667252 |   3)  d..1              |  default_idle_call() {
        354549.667252 |   3)  d..1              |    arch_cpu_idle() {
        354549.667253 |   3)  d..1              |      default_idle() {
        354549.696886 |   3)  d..1              |        smp_trace_reschedule_interrupt() {
        354549.696886 |   3)  d..1              |          irq_enter() {
        354549.696886 |   3)  d..1              |            rcu_irq_enter() {
      
      After the patch:
        366416.254476 |   3)  d..1              |    arch_cpu_idle() {
        366416.254476 |   3)  d..1              |      default_idle() {
        366416.261566 |   3)  d..1  ==========> |
        366416.261566 |   3)  d..1              |        smp_trace_reschedule_interrupt() {
        366416.261566 |   3)  d..1              |          irq_enter() {
        366416.261566 |   3)  d..1              |            rcu_irq_enter() {
      
      KASAN also uses this annotation. The smp_apic_timer_interrupt()
      was already annotated.
      Signed-off-by: default avatarDaniel Bristot de Oliveira <bristot@redhat.com>
      Acked-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
      Cc: Aaron Lu <aaron.lu@intel.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Baoquan He <bhe@redhat.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Claudio Fontana <claudio.fontana@huawei.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Dou Liyang <douly.fnst@cn.fujitsu.com>
      Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
      Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Nicolai Stange <nicstange@gmail.com>
      Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Wanpeng Li <wanpeng.li@hotmail.com>
      Cc: linux-edac@vger.kernel.org
      Link: http://lkml.kernel.org/r/059fdf437c2f0c09b13c18c8fe4e69999d3ffe69.1483528431.git.bristot@redhat.com
      
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      c4158ff5
  5. 09 Nov, 2016 1 commit
    • Wanpeng Li's avatar
      x86/apic: Prevent tracing on apic_msr_write_eoi() · 8ca22552
      Wanpeng Li authored
      
      
      The following RCU lockdep warning led to adding irq_enter()/irq_exit() into
      smp_reschedule_interrupt():
      
       RCU used illegally from idle CPU!
       rcu_scheduler_active = 1, debug_locks = 0
       RCU used illegally from extended quiescent state!
       no locks held by swapper/1/0.
       
        do_trace_write_msr
        native_write_msr
        native_apic_msr_eoi_write
        smp_reschedule_interrupt
        reschedule_interrupt
      
      As Peterz pointed out:
      
      | So now we're making a very frequent interrupt slower because of debug 
      | code.
      |
      | The thing is, many many smp_reschedule_interrupt() invocations don't
      | actually execute anything much at all and are only sent to tickle the
      | return to user path (which does the actual preemption).
      | 
      | Having to do the whole irq_enter/irq_exit dance just for this unlikely
      | debug case totally blows.
      
      Use the wrmsr_notrace() variant in native_apic_msr_write_eoi, annotate the
      kvm variant with notrace and add a native_apic_eoi callback to the apic
      structure so KVM guests are covered as well.
      
      This allows to revert the irq_enter/irq_exit dance in
      smp_reschedule_interrupt().
      Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
      Suggested-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: default avatarWanpeng Li <wanpeng.li@hotmail.com>
      Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      Cc: kvm@vger.kernel.org
      Cc: Mike Galbraith <efault@gmx.de>
      Cc: Borislav Petkov <bp@alien8.de>
      Link: http://lkml.kernel.org/r/1478488420-5982-3-git-send-email-wanpeng.li@hotmail.com
      
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      8ca22552
  6. 14 Oct, 2016 1 commit
    • Wanpeng Li's avatar
      x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() · 1ec6ec14
      Wanpeng Li authored
      
      
       ===============================
       [ INFO: suspicious RCU usage. ]
       4.8.0+ #24 Not tainted
       -------------------------------
       ./arch/x86/include/asm/msr-trace.h:47 suspicious rcu_dereference_check() usage!
       
       other info that might help us debug this:
       
       RCU used illegally from idle CPU!
       rcu_scheduler_active = 1, debug_locks = 0
       RCU used illegally from extended quiescent state!
       no locks held by swapper/1/0.
       
        [<ffffffff9d492b95>] do_trace_write_msr+0x135/0x140
        [<ffffffff9d06f860>] native_write_msr+0x20/0x30
        [<ffffffff9d065fad>] native_apic_msr_eoi_write+0x1d/0x30
        [<ffffffff9d05bd1d>] smp_reschedule_interrupt+0x1d/0x30
        [<ffffffff9d8daec6>] reschedule_interrupt+0x96/0xa0
      
      Reschedule interrupt may be called in cpu idle state. This causes lockdep 
      check warning above. 
      
      Add irq_enter/exit() in smp_reschedule_interrupt(), irq_enter() tells the RCU 
      subsystems to end the extended quiescent state, so the following trace call in 
      ack_APIC_irq() works correctly.
      Signed-off-by: default avatarWanpeng Li <wanpeng.li@hotmail.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Mike Galbraith <efault@gmx.de>
      Link: http://lkml.kernel.org/r/1476409733-5133-1-git-send-email-wanpeng.li@hotmail.com
      
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      1ec6ec14
  7. 11 Oct, 2016 1 commit
    • Hidehiro Kawai's avatar
      x86/panic: replace smp_send_stop() with kdump friendly version in panic path · 0ee59413
      Hidehiro Kawai authored
      Daniel Walker reported problems which happens when
      crash_kexec_post_notifiers kernel option is enabled
      (https://lkml.org/lkml/2015/6/24/44).
      
      In that case, smp_send_stop() is called before entering kdump routines
      which assume other CPUs are still online.  As the result, for x86, kdump
      routines fail to save other CPUs' registers and disable virtualization
      extensions.
      
      To fix this problem, call a new kdump friendly function,
      crash_smp_send_stop(), instead of the smp_send_stop() when
      crash_kexec_post_notifiers is enabled.  crash_smp_send_stop() is a weak
      function, and it just call smp_send_stop().  Architecture codes should
      override it so that kdump can work appropriately.  This patch only
      provides x86-specific version.
      
      For Xen's PV kernel, just keep the current behavior.
      
      NOTES:
      
      - Right solution would be to place crash_smp_send_stop() before
        __crash_kexec() invocation in all cases and remove smp_send_stop(), but
        we can't do that until all architectures implement own
        crash_smp_send_stop()
      
      - crash_smp_send_stop()-like work is still needed by
        machine_crash_shutdown() because crash_kexec() can be called without
        entering panic()
      
      Fixes: f06e5153 (kernel/panic.c: add "crash_kexec_post_notifiers" option)
      Link: http://lkml.kernel.org/r/20160810080948.11028.15344.stgit@sysi4-13.yrl.intra.hitachi.co.jp
      
      Signed-off-by: default avatarHidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
      Reported-by: default avatarDaniel Walker <dwalker@fifo99.com>
      Cc: Dave Young <dyoung@redhat.com>
      Cc: Baoquan He <bhe@redhat.com>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Masami Hiramatsu <mhiramat@kernel.org>
      Cc: Daniel Walker <dwalker@fifo99.com>
      Cc: Xunlei Pang <xpang@redhat.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: David Vrabel <david.vrabel@citrix.com>
      Cc: Toshi Kani <toshi.kani@hpe.com>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: David Daney <david.daney@cavium.com>
      Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
      Cc: "Steven J. Hill" <steven.hill@cavium.com>
      Cc: Corey Minyard <cminyard@mvista.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0ee59413
  8. 05 Nov, 2015 2 commits
  9. 13 Aug, 2015 1 commit
  10. 15 May, 2015 1 commit
  11. 05 May, 2014 1 commit
  12. 06 Aug, 2013 1 commit
  13. 02 Jul, 2013 1 commit
    • Seiji Aguchi's avatar
      x86/tracing: Add irq_enter/exit() in smp_trace_reschedule_interrupt() · 4787c368
      Seiji Aguchi authored
      Reschedule vector tracepoints may be called in cpu idle state.
      This causes lockdep check warning below.
      
      The tracepoint requires rcu but for accuracy it also
      requires irq_enter() (tracepoints record the irq context), thus,
      the tracepoint interrupt handler should be calling irq_enter()
      and not rcu_irq_enter() (irq_enter() calls rcu_irq_enter()).
      
      So, add irq_enter/exit() to smp_trace_reschedule_interrupt()
      with common pre/post processing functions, smp_entering_irq()
      and exiting_irq() (exiting_irq() calls just irq_exit()
       in arch/x86/include/asm/apic.h),
      because these can be shared among reschedule, call_function,
      and call_function_single vectors.
      
      [   50.720557] Testing event reschedule_exit:
      [   50.721349]
      [   50.721502] ===============================
      [   50.721835] [ INFO: suspicious RCU usage. ]
      [   50.722169] 3.10.0-rc6-00004-gcf910e83
      
       #190 Not tainted
      [   50.722582] -------------------------------
      [   50.722915] /c/kernel-tests/src/linux/arch/x86/include/asm/trace/irq_vectors.h:50 suspicious rcu_dereference_check() usage!
      [   50.723770]
      [   50.723770] other info that might help us debug this:
      [   50.723770]
      [   50.724385]
      [   50.724385] RCU used illegally from idle CPU!
      [   50.724385] rcu_scheduler_active = 1, debug_locks = 0
      [   50.725232] RCU used illegally from extended quiescent state!
      [   50.725690] no locks held by swapper/0/0.
      [   50.726010]
      [   50.726010] stack backtrace:
      [...]
      Signed-off-by: default avatarSeiji Aguchi <seiji.aguchi@hds.com>
      Reviewed-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Link: http://lkml.kernel.org/r/51CDCFA3.9080101@hds.com
      
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      4787c368
  14. 21 Jun, 2013 2 commits
    • Seiji Aguchi's avatar
      x86, trace: Add irq vector tracepoints · cf910e83
      Seiji Aguchi authored
      [Purpose of this patch]
      
      As Vaibhav explained in the thread below, tracepoints for irq vectors
      are useful.
      
      http://www.spinics.net/lists/mm-commits/msg85707.html
      
      
      
      <snip>
      The current interrupt traces from irq_handler_entry and irq_handler_exit
      provide when an interrupt is handled.  They provide good data about when
      the system has switched to kernel space and how it affects the currently
      running processes.
      
      There are some IRQ vectors which trigger the system into kernel space,
      which are not handled in generic IRQ handlers.  Tracing such events gives
      us the information about IRQ interaction with other system events.
      
      The trace also tells where the system is spending its time.  We want to
      know which cores are handling interrupts and how they are affecting other
      processes in the system.  Also, the trace provides information about when
      the cores are idle and which interrupts are changing that state.
      <snip>
      
      On the other hand, my usecase is tracing just local timer event and
      getting a value of instruction pointer.
      
      I suggested to add an argument local timer event to get instruction pointer before.
      But there is another way to get it with external module like systemtap.
      So, I don't need to add any argument to irq vector tracepoints now.
      
      [Patch Description]
      
      Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events.
      But there is an above use case to trace specific irq_vector rather than tracing all events.
      In this case, we are concerned about overhead due to unwanted events.
      
      So, add following tracepoints instead of introducing irq_vector_entry/exit.
      so that we can enable them independently.
         - local_timer_vector
         - reschedule_vector
         - call_function_vector
         - call_function_single_vector
         - irq_work_entry_vector
         - error_apic_vector
         - thermal_apic_vector
         - threshold_apic_vector
         - spurious_apic_vector
         - x86_platform_ipi_vector
      
      Also, introduce a logic switching IDT at enabling/disabling time so that a time penalty
      makes a zero when tracepoints are disabled. Detailed explanations are as follows.
       - Create trace irq handlers with entering_irq()/exiting_irq().
       - Create a new IDT, trace_idt_table, at boot time by adding a logic to
         _set_gate(). It is just a copy of original idt table.
       - Register the new handlers for tracpoints to the new IDT by introducing
         macros to alloc_intr_gate() called at registering time of irq_vector handlers.
       - Add checking, whether irq vector tracing is on/off, into load_current_idt().
         This has to be done below debug checking for these reasons.
         - Switching to debug IDT may be kicked while tracing is enabled.
         - On the other hands, switching to trace IDT is kicked only when debugging
           is disabled.
      
      In addition, the new IDT is created only when CONFIG_TRACING is enabled to avoid being
      used for other purposes.
      Signed-off-by: default avatarSeiji Aguchi <seiji.aguchi@hds.com>
      Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.com
      
      Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      cf910e83
    • Seiji Aguchi's avatar
      x86, trace: Introduce entering/exiting_irq() · eddc0e92
      Seiji Aguchi authored
      
      
      When implementing tracepoints in interrupt handers, if the tracepoints are
      simply added in the performance sensitive path of interrupt handers,
      it may cause potential performance problem due to the time penalty.
      
      To solve the problem, an idea is to prepare non-trace/trace irq handers and
      switch their IDTs at the enabling/disabling time.
      
      So, let's introduce entering_irq()/exiting_irq() for pre/post-
      processing of each irq handler.
      
      A way to use them is as follows.
      
      Non-trace irq handler:
      smp_irq_handler()
      {
      	entering_irq();		/* pre-processing of this handler */
      	__smp_irq_handler();	/*
      				 * common logic between non-trace and trace handlers
      				 * in a vector.
      				 */
      	exiting_irq();		/* post-processing of this handler */
      
      }
      
      Trace irq_handler:
      smp_trace_irq_handler()
      {
      	entering_irq();		/* pre-processing of this handler */
      	trace_irq_entry();	/* tracepoint for irq entry */
      	__smp_irq_handler();	/*
      				 * common logic between non-trace and trace handlers
      				 * in a vector.
      				 */
      	trace_irq_exit();	/* tracepoint for irq exit */
      	exiting_irq();		/* post-processing of this handler */
      
      }
      
      If tracepoints can place outside entering_irq()/exiting_irq() as follows,
      it looks cleaner.
      
      smp_trace_irq_handler()
      {
      	trace_irq_entry();
      	smp_irq_handler();
      	trace_irq_exit();
      }
      
      But it doesn't work.
      The problem is with irq_enter/exit() being called. They must be called before
      trace_irq_enter/exit(),  because of the rcu_irq_enter() must be called before
      any tracepoints are used, as tracepoints use  rcu to synchronize.
      
      As a possible alternative, we may be able to call irq_enter() first as follows
      if irq_enter() can nest.
      
      smp_trace_irq_hander()
      {
      	irq_entry();
      	trace_irq_entry();
      	smp_irq_handler();
      	trace_irq_exit();
      	irq_exit();
      }
      
      But it doesn't work, either.
      If irq_enter() is nested, it may have a time penalty because it has to check if it
      was already called or not. The time penalty is not desired in performance sensitive
      paths even if it is tiny.
      Signed-off-by: default avatarSeiji Aguchi <seiji.aguchi@hds.com>
      Link: http://lkml.kernel.org/r/51C3238D.9040706@hds.com
      
      Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      eddc0e92
  15. 14 May, 2012 3 commits
    • Don Zickus's avatar
      x86/reboot: Update nonmi_ipi parameter · 3aac27ab
      Don Zickus authored
      
      
      Update the nonmi_ipi parameter to reflect the simple change
      instead of the previous complicated one.  There should be less
      of a need to use it but there may still be corner cases on older
      hardware that stumble into NMI issues.
      Signed-off-by: default avatarDon Zickus <dzickus@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Link: http://lkml.kernel.org/r/1336761675-24296-4-git-send-email-dzickus@redhat.com
      
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      3aac27ab
    • Don Zickus's avatar
      x86/reboot: Use NMI to assist in shutting down if IRQ fails · 7d007d21
      Don Zickus authored
      
      
      For v3.3, I added code to use the NMI to stop other cpus in the
      panic case.  The idea was to make sure all cpus on the system
      were definitely halted to help serialize the panic path to
      execute the rest of the code on a single cpu.
      
      The main problem it was trying to solve was how to stop a cpu
      that was spinning with its irqs disabled.  A IPI irq would be
      stuck and couldn't get in there, but an NMI could.
      
      Things were great until we had another conversation about some
      pstore changes.  Because some of the backend pstore still uses
      spinlocks to protect the device access, things could get ugly if
      a panic happened and we were stuck spinning on a lock.
      
      Now with the NMI shutting down cpus, we could assume no other
      cpus were running and just bust the spin lock and proceed.
      
      The counter argument was, well if you do that the backend could
      be in a screwed up state and you might not be able to save
      anything as a result. If we could have just given the cpu a
      little more time to finish things, we could have grabbed the
      spin lock cleanly and everything would have been fine.
      
      Well, how do give a cpu a 'little more time' in the panic case?
      For the most part you can't without spinning on the lock and
      even in that case, how long do you spin for?
      
      So instead of making it ugly in the pstore code, just mimic the
      idea that stop_machine had, which is block on an IRQ IPI until
      the remote cpu has re-enabled interrupts and left the critical
      region.  Which is what happens now using REBOOT_IRQ.
      
      Then leave the NMI case for those cpus that are truly stuck
      after a short time.  This leaves the current behaviour alone and
      just handle a corner case.  Most systems should never have to
      enter the NMI code and if they do, print out a message in case
      the NMI itself causes another issue.
      Signed-off-by: default avatarDon Zickus <dzickus@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Link: http://lkml.kernel.org/r/1336761675-24296-3-git-send-email-dzickus@redhat.com
      
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      7d007d21
    • Don Zickus's avatar
      Revert "x86, reboot: Use NMI instead of REBOOT_VECTOR to stop cpus" · 5d2b86d9
      Don Zickus authored
      This reverts commit 3603a251
      
      .
      
      Originally I wanted a better hammer to shutdown cpus during
      panic. However, this really steps on the toes of various
      spinlocks in the panic path.  Sometimes it is easier to wait for
      the IRQ to become re-enabled to indictate the cpu left the
      critical region and then shutdown the cpu.
      
      The next patch moves the NMI addition after the IRQ part.  To
      make it easier to see the logic of everything, revert this patch
      and apply the next simpler patch.
      Signed-off-by: default avatarDon Zickus <dzickus@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Link: http://lkml.kernel.org/r/1336761675-24296-2-git-send-email-dzickus@redhat.com
      
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      5d2b86d9
  16. 07 Jan, 2012 1 commit
  17. 05 Dec, 2011 2 commits
    • Don Zickus's avatar
      x86, NMI: Add knob to disable using NMI IPIs to stop cpus · bda62633
      Don Zickus authored
      
      
      Some machines may exhibit problems using the NMI to stop other
      cpus. This knob just allows one to revert back to the original
      behaviour to help diagnose the problem.
      
      V2:
        make function static
      Signed-off-by: default avatarDon Zickus <dzickus@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Robert Richter <robert.richter@amd.com>
      Cc: seiji.aguchi@hds.com
      Cc: vgoyal@redhat.com
      Cc: mjg@redhat.com
      Cc: tony.luck@intel.com
      Cc: gong.chen@intel.com
      Cc: satoru.moriya@hds.com
      Cc: avi@redhat.com
      Cc: Andi Kleen <andi@firstfloor.org>
      Link: http://lkml.kernel.org/r/1318533267-18880-4-git-send-email-dzickus@redhat.com
      
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      bda62633
    • Don Zickus's avatar
      x86, reboot: Use NMI instead of REBOOT_VECTOR to stop cpus · 3603a251
      Don Zickus authored
      
      
      A recent discussion started talking about the locking on the
      pstore fs and how it relates to the kmsg infrastructure.  We
      noticed it was possible for userspace to r/w to the pstore fs
      (grabbing the locks in the process) and block the panic path
      from r/w to the same fs.
      
      The reason was the cpu with the lock could be doing work while
      the crashing cpu is panic'ing.  Busting those spinlocks might
      cause those cpus to step on each other's data.  Fine, fair
      enough.
      
      It was suggested it would be nice to serialize the panic path
      (ie stop the other cpus) and have only one cpu running.  This
      would allow us to bust the spinlocks and not worry about another
      cpu stepping on the data.
      
      Of course, smp_send_stop() does this in the panic case.
      kmsg_dump() would have to be moved to be called after it.  Easy
      enough.
      
      The only problem is on x86 the smp_send_stop() function calls
      the REBOOT_VECTOR.  Any cpu with irqs disabled (which pstore and
      its backend ERST would do), block this IPI and thus do not stop.
       This makes it difficult to reliably log data to the pstore fs.
      
      The patch below switches from the REBOOT_VECTOR to NMI (and
      mimics what kdump does).  Switching to NMI allows us to deliver
      the IPI when irqs are disabled, increasing the reliability of
      this function.
      
      However, Andi carefully noted that on some machines this
      approach does not work because of broken BIOSes or whatever.
      
      To help accomodate this, the next couple of patches will run a
      selftest and provide a knob to disable.
      
      V2:
        uses atomic ops to serialize the cpu that shuts everyone down
      V3:
        comment cleanup
      Signed-off-by: default avatarDon Zickus <dzickus@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Robert Richter <robert.richter@amd.com>
      Cc: seiji.aguchi@hds.com
      Cc: vgoyal@redhat.com
      Cc: mjg@redhat.com
      Cc: tony.luck@intel.com
      Cc: gong.chen@intel.com
      Cc: satoru.moriya@hds.com
      Cc: avi@redhat.com
      Cc: Andi Kleen <andi@firstfloor.org>
      Link: http://lkml.kernel.org/r/1318533267-18880-2-git-send-email-dzickus@redhat.com
      
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      3603a251
  18. 31 Oct, 2011 1 commit
    • Paul Gortmaker's avatar
      x86: Fix files explicitly requiring export.h for EXPORT_SYMBOL/THIS_MODULE · 69c60c88
      Paul Gortmaker authored
      
      
      These files were implicitly getting EXPORT_SYMBOL via device.h
      which was including module.h, but that will be fixed up shortly.
      
      By fixing these now, we can avoid seeing things like:
      
      arch/x86/kernel/rtc.c:29: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’
      arch/x86/kernel/pci-dma.c:20: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’
      arch/x86/kernel/e820.c:69: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL_GPL’
      
      [ with input from Randy Dunlap <rdunlap@xenotime.net> and also
        from Stephen Rothwell <sfr@canb.auug.org.au> ]
      Signed-off-by: default avatarPaul Gortmaker <paul.gortmaker@windriver.com>
      69c60c88
  19. 14 Apr, 2011 1 commit
  20. 21 Oct, 2010 1 commit
    • Alok Kataria's avatar
      x86, kexec: Make sure to stop all CPUs before exiting the kernel · 76fac077
      Alok Kataria authored
      x86 smp_ops now has a new op, stop_other_cpus which takes a parameter
      "wait" this allows the caller to specify if it wants to stop until all
      the cpus have processed the stop IPI.  This is required specifically
      for the kexec case where we should wait for all the cpus to be stopped
      before starting the new kernel.  We now wait for the cpus to stop in
      all cases except for panic/kdump where we expect things to be broken
      and we are doing our best to make things work anyway.
      
      This patch fixes a legitimate regression, which was introduced during
      2.6.30, by commit id 4ef702c1
      
      .
      Signed-off-by: default avatarAlok N Kataria <akataria@vmware.com>
      LKML-Reference: <1286833028.1372.20.camel@ank32.eng.vmware.com>
      Cc: Eric W. Biederman <ebiederm@xmission.com>
      Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
      Cc: <stable@kernel.org> v2.6.30-36
      Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
      76fac077
  21. 30 Mar, 2010 1 commit
    • Tejun Heo's avatar
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
      Tejun Heo authored
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
      
      percpu.h is included by sched.h and module.h and thus ends up being
      included when building most .c files.  percpu.h includes slab.h which
      in turn includes gfp.h making everything defined by the two files
      universally available and complicating inclusion dependencies.
      
      percpu.h -> slab.h dependency is about to be removed.  Prepare for
      this change by updating users of gfp and slab facilities include those
      headers directly instead of assuming availability.  As this conversion
      needs to touch large number of source files, the following script is
      used as the basis of conversion.
      
        http://userweb.kernel.org/~tj/misc/slabh-sweep.py
      
      
      
      The script does the followings.
      
      * Scan files for gfp and slab usages and update includes such that
        only the necessary includes are there.  ie. if only gfp is used,
        gfp.h, if slab is used, slab.h.
      
      * When the script inserts a new include, it looks at the include
        blocks and try to put the new include such that its order conforms
        to its surrounding.  It's put in the include block which contains
        core kernel includes, in the same order that the rest are ordered -
        alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
        doesn't seem to be any matching order.
      
      * If the script can't find a place to put a new include (mostly
        because the file doesn't have fitting include block), it prints out
        an error message indicating which .h file needs to be added to the
        file.
      
      The conversion was done in the following steps.
      
      1. The initial automatic conversion of all .c files updated slightly
         over 4000 files, deleting around 700 includes and adding ~480 gfp.h
         and ~3000 slab.h inclusions.  The script emitted errors for ~400
         files.
      
      2. Each error was manually checked.  Some didn't need the inclusion,
         some needed manual addition while adding it to implementation .h or
         embedding .c file was more appropriate for others.  This step added
         inclusions to around 150 files.
      
      3. The script was run again and the output was compared to the edits
         from #2 to make sure no file was left behind.
      
      4. Several build tests were done and a couple of problems were fixed.
         e.g. lib/decompress_*.c used malloc/free() wrappers around slab
         APIs requiring slab.h to be added manually.
      
      5. The script was run on all .h files but without automatically
         editing them as sprinkling gfp.h and slab.h inclusions around .h
         files could easily lead to inclusion dependency hell.  Most gfp.h
         inclusion directives were ignored as stuff from gfp.h was usually
         wildly available and often used in preprocessor macros.  Each
         slab.h inclusion directive was examined and added manually as
         necessary.
      
      6. percpu.h was updated not to include slab.h.
      
      7. Build test were done on the following configurations and failures
         were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
         distributed build env didn't work with gcov compiles) and a few
         more options had to be turned off depending on archs to make things
         build (like ipr on powerpc/64 which failed due to missing writeq).
      
         * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
         * powerpc and powerpc64 SMP allmodconfig
         * sparc and sparc64 SMP allmodconfig
         * ia64 SMP allmodconfig
         * s390 SMP allmodconfig
         * alpha SMP allmodconfig
         * um on x86_64 SMP allmodconfig
      
      8. percpu.h modifications were reverted so that it could be applied as
         a separate patch and serve as bisection point.
      
      Given the fact that I had only a couple of failures from tests on step
      6, I'm fairly confident about the coverage of this conversion patch.
      If there is a breakage, it's likely to be something in one of the arch
      headers which should be easily discoverable easily on most builds of
      the specific arch.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Guess-its-ok-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      5a0e3ad6
  22. 09 Oct, 2009 1 commit
    • Ingo Molnar's avatar
      Revert "x86, timers: Check for pending timers after (device) interrupts" · e7ab0f7b
      Ingo Molnar authored
      This reverts commit 9bcbdd9c.
      
      The real bug producing LatencyTop latencies has been fixed in:
      
        f5dc3753
      
      : sched: Update the clock of runqueue select_task_rq() selected
      
      And the commit being reverted here triggers local timer processing
      from every device IRQ. If device IRQs come in at a high frequency,
      this could cause a performance regression.
      
      The commit being reverted here purely 'fixed' the reported latency
      as a side effect, because CPUs were being moved out of idle more
      often.
      Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
      Cc: Arjan van de Ven <arjan@linux.intel.com>
      Cc: Frans Pop <elendil@planet.nl>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Mike Galbraith <efault@gmx.de>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      LKML-Reference: <20091008064041.67219b13@infradead.org>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      e7ab0f7b
  23. 08 Oct, 2009 1 commit
    • Arjan van de Ven's avatar
      x86, timers: Check for pending timers after (device) interrupts · 9bcbdd9c
      Arjan van de Ven authored
      
      
      Now that range timers and deferred timers are common, I found a
      problem with these using the "perf timechart" tool. Frans Pop also
      reported high scheduler latencies via LatencyTop, when using
      iwlagn.
      
      It turns out that on x86, these two 'opportunistic' timers only get
      checked when another "real" timer happens. These opportunistic
      timers have the objective to save power by hitchhiking on other
      wakeups, as to avoid CPU wakeups by themselves as much as possible.
      
      The change in this patch runs this check not only at timer
      interrupts, but at all (device) interrupts. The effect is that:
      
       1) the deferred timers/range timers get delayed less
      
       2) the range timers cause less wakeups by themselves because
          the percentage of hitchhiking on existing wakeup events goes up.
      
      I've verified the working of the patch using "perf timechart", the
      original exposed bug is gone with this patch. Frans also reported
      success - the latencies are now down in the expected ~10 msec
      range.
      Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
      Tested-by: default avatarFrans Pop <elendil@planet.nl>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Mike Galbraith <efault@gmx.de>
      LKML-Reference: <20091008064041.67219b13@infradead.org>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      9bcbdd9c
  24. 10 Jun, 2009 1 commit
    • Marcelo Tosatti's avatar
      KVM: use smp_send_reschedule in kvm_vcpu_kick · 32f88400
      Marcelo Tosatti authored
      
      
      KVM uses a function call IPI to cause the exit of a guest running on a
      physical cpu. For virtual interrupt notification there is no need to
      wait on IPI receival, or to execute any function.
      
      This is exactly what the reschedule IPI does, without the overhead
      of function IPI. So use it instead of smp_call_function_single in
      kvm_vcpu_kick.
      
      Also change the "guest_mode" variable to a bit in vcpu->requests, and
      use that to collapse multiple IPI's that would be issued between the
      first one and zeroing of guest mode.
      
      This allows kvm_vcpu_kick to called with interrupts disabled.
      Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
      Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
      32f88400
  25. 03 Jun, 2009 1 commit
    • Andi Kleen's avatar
      x86: fix panic with interrupts off (needed for MCE) · 4ef702c1
      Andi Kleen authored
      
      
      For some time each panic() called with interrupts disabled
      triggered the !irqs_disabled() WARN_ON in smp_call_function(),
      producing ugly backtraces and confusing users.
      
      This is a common situation with machine checks for example which
      tend to call panic with interrupts disabled, but will also hit
      in other situations e.g. panic during early boot.  In fact it
      means that panic cannot be called in many circumstances, which
      would be bad.
      
      This all started with the new fancy queued smp_call_function,
      which is then used by the shutdown path to shut down the other
      CPUs.
      
      On closer examination it turned out that the fancy RCU
      smp_call_function() does lots of things not suitable in a panic
      situation anyways, like allocating memory and relying on complex
      system state.
      
      I originally tried to patch this over by checking for panic
      there, but it was quite complicated and the original patch
      was also not very popular.  This also didn't fix some of the
      underlying complexity problems.
      
      The new code in post 2.6.29 tries to patch around this by
      checking for oops_in_progress, but that is not enough to make
      this fully safe and I don't think that's a real solution
      because panic has to be reliable.
      
      So instead use an own vector to reboot.  This makes the reboot
      code extremly straight forward, which is definitely a big plus
      in a panic situation where it is important to avoid relying on
      too much kernel state.  The new simple code is also safe to be
      called from interupts off region because it is very very simple.
      
      There can be situations where it is important that panic
      is reliable.  For example on a fatal machine check the panic
      is needed to get the system up again and running as quickly
      as possible.  So it's important that panic is reliable and
      all function it calls simple.
      
      This is why I came up with this simple vector scheme.
      It's very hard to beat in simplicity.  Vectors are not
      particularly precious anymore since all big systems are
      using per CPU vectors.
      
      Another possibility would have been to use an NMI similar
      to kdump, but there is still the problem that NMIs don't
      work reliably on some systems due to BIOS issues.  NMIs
      would have been able to stop CPUs running with interrupts
      off too.  In the sake of universal reliability I opted for
      using a non NMI vector for now.
      
      I put the reboot vector into the highest priority bucket of
      the APIC vectors and moved the 64bit UV_BAU message down
      instead into the next lower priority.
      
      [ Impact: bug fix, fixes an old regression ]
      Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
      Signed-off-by: default avatarHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
      Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
      4ef702c1
  26. 12 Apr, 2009 1 commit
  27. 17 Feb, 2009 1 commit
  28. 31 Jan, 2009 1 commit
  29. 29 Jan, 2009 2 commits
  30. 28 Jan, 2009 1 commit
    • Ingo Molnar's avatar
      x86, apic: untangle the send_IPI_*() jungle · dac5f412
      Ingo Molnar authored
      
      
      Our send_IPI_*() methods and definitions are a twisted mess: the same
      symbol is defined to different things depending on .config details,
      in a non-transparent way.
      
       - spread out the quirks into separately named per apic driver methods
      
       - prefix the standard PC methods with default_
      
       - get rid of wrapper macro obfuscation
      
       - clean up various details
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      dac5f412
  31. 05 Jan, 2009 1 commit