linux-toradex.git/arch/ia64/kernel/crash.c, branch v4.2.7

ia64: convert use of typedef ctl_table to struct ctl_table

2014-06-06T23:08:15+00:00

This typedef is unnecessary and should just be removed.

Signed-off-by: Joe Perches 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sysctl: Drop & in front of every proc_handler.

2009-11-18T16:37:40+00:00

For consistency drop & in front of every proc_handler.  Explicity
taking the address is unnecessary and it prevents optimizations
like stubbing the proc_handlers to NULL.

Cc: Alexey Dobriyan 
Cc: Ingo Molnar 
Cc: Joe Perches 
Signed-off-by: Eric W. Biederman

sysctl ia64: Remove dead binary sysctl support

2009-11-12T10:05:01+00:00

Now that sys_sysctl is a generic wrapper around /proc/sys  .ctl_name
and .strategy members of sysctl tables are dead code.  Remove them.

Cc: Tony Luck 
Cc: Fenghua Yu 
Signed-off-by: Eric W. Biederman

[IA64] kdump: Short path to freeze CPUs

2009-09-14T23:19:24+00:00

Setting monarch_cpu = -1 to let slaves frozen might not work, because
there might be slaves being late, not entered the rendezvous yet.
Such slaves might be caught in while (monarch_cpu == -1) loop.

Use kdump_in_progress instead of monarch_cpus to break INIT rendezvous
and let all slaves enter DIE_INIT_SLAVE_LEAVE smoothly.

And monarch no longer need to manage rendezvous if once kdump_in_progress
is set, catch the monarch in DIE_INIT_MONARCH_ENTER then.

Signed-off-by: Hidetoshi Seto 
Cc: Vivek Goyal 
Cc: Haren Myneni 
Cc: kexec@lists.infradead.org
Acked-by: Fenghua Yu 
Signed-off-by: Tony Luck

[IA64] kdump: Try INIT regardless of

2009-09-14T23:19:10+00:00

kdump_on_init

CPUs should be frozen if possible, otherwise it might hinder kdump.
So if there are CPUs not respond to IPI, try INIT to stop them.

Signed-off-by: Hidetoshi Seto 
Cc: Vivek Goyal 
Cc: Haren Myneni 
Cc: kexec@lists.infradead.org
Acked-by: Fenghua Yu 
Signed-off-by: Tony Luck

[IA64] kdump: Mask INIT first in panic-kdump path

2009-09-14T23:18:54+00:00

Summary:

  Asserting INIT might block kdump if the system is already going to
  start kdump via panic.

Description:

  INIT can interrupt anywhere in panic path, so it can interrupt in
  middle of kdump kicked by panic.  Therefore there is a race if kdump
  is kicked concurrently, via Panic and via INIT.

  INIT could fail to invoke kdump if the system is already going to
  start kdump via panic.  It could not restart kdump from INIT handler
  if some of cpus are already playing dead with INIT masked.  It also
  means that INIT could block kdump's progress if no monarch is entered
  in the INIT rendezvous.

  Panic+INIT is a rare, but possible situation since it can be assumed
  that the kernel or an internal agent decides to panic the unstable
  system while another external agent decides to send an INIT to the
  system at same time.

How to reproduce:

  Assert INIT just after panic, before all other cpus have frozen

Expected results:

  continue kdump invoked by panic, or restart kdump from INIT

Actual results:

  might be hang, crashdump not retrieved

Proposed Fix:

  This patch masks INIT first in panic path to take the initiative on
  kdump, and reuse atomic value kdump_in_progress to make sure there is
  only one initiator of kdump.  All INITs asserted later should be used
  only for freezing all other cpus.

  This mask will be removed soon by rfi in relocate_kernel.S, before jump
  into kdump kernel, after all cpus are frozen and no-op INIT handler is
  registered.  So if INIT was in the interval while it is masked, it will
  pend on the system and will received just after the rfi, and handled by
  the no-op handler.

  If there was a MCA event while psr.mc is 1, in theory the event will
  pend on the system and will received just after the rfi same as above.
  MCA handler is unregistered here at the time, so received MCA will not
  reach to OS_MCA and will result in warmboot by SAL.

  Note that codes in this masked interval are relatively simpler than
  that in MCA/INIT handler which also executed with the mask.  So it can
  be said that probability of error in this interval is supposed not so
  higher than that in MCA/INIT handler.

Signed-off-by: Hidetoshi Seto 
Cc: Vivek Goyal 
Cc: Haren Myneni 
Cc: kexec@lists.infradead.org
Acked-by: Fenghua Yu 
Signed-off-by: Tony Luck

[IA64] kdump: Don't return APs to SAL from kdump

2009-09-14T23:18:37+00:00

Summary:

  Asserting INIT on cpu going to be offline will result in unexpected
  behavior.  It will be a real problem in kdump cases where INIT might
  be asserted to unstable APs going to be offline by returning to SAL.

Description:

  Since psr.mc is cleared when bits in psr are set to SAL_PSR_BITS_TO_SET
  in ia64_jump_to_sal(), there is a small window (~few msecs) that the
  cpu can receive INIT even if the cpu enter there via INIT handler.
  In this window we do restore of registers for SAL, so INIT asserted
  here will not work properly.

  It is hard to remove this window by masking INIT (i.e. setting psr.mc)
  because we have to unmask it later in OS, because we have to use branch
  instruction (br.ret, not rfi) to return SAL, due to OS_BOOT_RENDEZ to
  SAL return convention.

  I suppose this window will not be a real problem on cpu offline if we
  can educate people not to push INIT button during hotplug operation.
  However, only exception is a race in kdump and INIT.  Now kdump returns
  APs to SAL before processing dump, but the kernel might receive INIT at
  that point in time.  Such INIT might be asserted by kdump itself if an
  AP doesn't react IPI soon and kdump decided to use INIT to stop the AP.
  Or it might be asserted by operator or an external agent to start dump
  on the unstable system.

  Such panic+INIT or INIT+INIT cases should be rare, but it will be happy
  if we can retrieve crashdump even in such cases.

How to reproduce:

  panic+INIT or INIT+INIT, with kdump configured

Expected results:

  crashdump is retrieved anyway

Actual results:

  panic, hang etc. (unexpected)

Proposed fix

  To avoid the window on the way to SAL, this patch stops returning APs
  to SAL in case of kdump.  In other words, this patch makes APs spin
  in OS instead of spinning in SAL.

  (* Note: What impact would be there?  If a cpu is spinning in SAL,
   the cpu is in BOOT_RENDEZ loop, as same as offlined cpu.
   In theory if an INIT is asserted there, cpus in the BOOT_RENDEZ loop
   should not invoke OS_INIT on it.  So in either way, no matter where
   the cpu is spinning actually in, once cpu starts spin and act as
   "frozen," INIT on the cpu have no effects.
   From another point of view, all debug information on the cpu should
   have stored to memory before the cpu start to be frozen.  So no more
   action on the cpu is required.)

  I confirmed that the kdump sometime hangs by concurrent INITs (another
  INIT after an INIT), and it doesn't hang after applying this patch.

Signed-off-by: Hidetoshi Seto 
Cc: Vivek Goyal 
Cc: Haren Myneni 
Cc: kexec@lists.infradead.org
Acked-by: Fenghua Yu 
Signed-off-by: Tony Luck

[IA64] kdump: Mask MCA/INIT on frozen cpus

2009-09-14T23:17:05+00:00

Summary:

  INIT asserted on kdump kernel invokes INIT handler not only on a
  cpu that running on the kdump kernel, but also BSP of the panicked
  kernel, because the (badly) frozen BSP can be thawed by INIT.

Description:

  The kdump_cpu_freeze() is called on cpus except one that initiates
  panic and/or kdump, to stop/offline the cpu (on ia64, it means we
  pass control of cpus to SAL, or put them in spinloop).  Note that
  CPU0(BSP) always go to spinloop, so if panic was happened on an AP,
  there are at least 2cpus (= the AP and BSP) which not back to SAL.

  On the spinning cpus, interrupts are disabled (rsm psr.i), but INIT
  is still interruptible because psr.mc for mask them is not set unless
  kdump_cpu_freeze() is not called from MCA/INIT context.

  Therefore, assume that a panic was happened on an AP, kdump was
  invoked, new INIT handlers for kdump kernel was registered and then
  an INIT is asserted.  From the viewpoint of SAL, there are 2 online
  cpus, so INIT will be delivered to both of them.  It likely means
  that not only the AP (= a cpu executing kdump) enters INIT handler
  which is newly registered, but also BSP (= another cpu spinning in
  panicked kernel) enters the same INIT handler.  Of course setting of
  registers in BSP are still old (for panicked kernel), so what happen
  with running handler with wrong setting will be extremely unexpected.
  I believe this is not desirable behavior.

How to Reproduce:

  Start kdump on one of APs (e.g. cpu1)
    # taskset 0x2 echo c > /proc/sysrq-trigger
  Then assert INIT after kdump kernel is booted, after new INIT handler
  for kdump kernel is registered.

Expected results:

  An INIT handler is invoked only on the AP.

Actual results:

  An INIT handler is invoked on the AP and BSP.

Sample of results:

  I got following console log by asserting INIT after prompt "root:/>".
  It seems that two monarchs appeared by one INIT, and one panicked at
  last.  And it also seems that the panicked one supposed there were
  4 online cpus and no one did rendezvous:

    :
    [  0 %]dropping to initramfs shell
    exiting this shell will reboot your system
    root:/> Entered OS INIT handler. PSP=fff301a0 cpu=0 monarch=0
    ia64_init_handler: Promoting cpu 0 to monarch.
    Delaying for 5 seconds...
    All OS INIT slaves have reached rendezvous
    Processes interrupted by INIT - 0 (cpu 0 task 0xa000000100af0000)
    :
    <>
    :
    Entered OS INIT handler. PSP=fff301a0 cpu=0 monarch=1
    Delaying for 5 seconds...
    mlogbuf_finish: printing switched to urgent mode, MCA/INIT might be dodgy or fail.
    OS INIT slave did not rendezvous on cpu 1 2 3
    INIT swapper 0[0]: bugcheck! 0 [1]
    :
    <>
    :
    Kernel panic - not syncing: Attempted to kill the idle task!

Proposed fix:

  To avoid this problem, this patch inserts ia64_set_psr_mc() to mask
  INIT on cpus going to be frozen.  This masking have no effect if the
  kdump_cpu_freeze() is called from INIT handler when kdump_on_init == 1,
  because psr.mc is already turned on to 1 before entering OS_INIT.
  I confirmed that weird log like above are disappeared after applying
  this patch.

Signed-off-by: Hidetoshi Seto 
Cc: Vivek Goyal 
Cc: Haren Myneni 
Cc: kexec@lists.infradead.org
Acked-by: Fenghua Yu 
Signed-off-by: Tony Luck

[IA64] simplify notify hooks in mca.c

2008-04-22T15:56:38+00:00

There are many notify_die() and almost all take same style with
ia64_mca_spin().  This patch defines macros and replace them all,
to reduce lines and to improve readability.

Signed-off-by: Hidetoshi Seto 
Signed-off-by: Tony Luck

[IA64] kdump: Add crash_save_vmcoreinfo for INIT

2008-04-15T18:20:53+00:00

This patch fixes the problem that kdump by INIT does not work if we use
makedumpfile. The problem is that after INIT is issued, 2nd kernel
starts and makedumpfile fails with the following error message.

/proc/vmcore doesn't contain vmcoreinfo.
'-x' or '-i' must be specified.

makedumpfile Failed.

The cause of this problem is that kernel does not call
crash_save_vmcoreinfo. When kdump starts by panic or sysrq-trigger,
crash_save_vmcoreinfo is called by crash_kexec. But this function is not
called when kdump starts by INIT. The Attached patch fixes this.

This patch just adds crash_save_vmcoreinfo into machine_kdump_on_init so
that crash_save_vmcoreinfo can be called when kdump starts by INIT.
I tested this patch with linux-2.6.25-rc9 and I confirmed it worked.

Signed-off-by: Takao Indoh 
Signed-off-by: Tony Luck