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  1. 12 Apr, 2009 2 commits
    • Frederic Weisbecker's avatar
      lockdep: continue lock debugging despite some taints · 574bbe78
      Frederic Weisbecker authored 
      Impact: broaden lockdep checks

Lockdep is disabled after any kernel taints. This might be convenient
to ignore bad locking issues which sources come from outside the kernel
tree. Nevertheless, it might be a frustrating experience for the
staging developers or those who experience a warning but are focused
on another things that require lockdep.

The v2 of this patch simply don't disable anymore lockdep in case
of TAINT_CRAP and TAINT_WARN events.
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: LTP <ltp-list@lists.sourceforge.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg KH <gregkh@suse.de>
LKML-Reference: <1239412638-6739-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      574bbe78
    • Frederic Weisbecker's avatar
      lockdep: warn about lockdep disabling after kernel taint · 9eeba613
      Frederic Weisbecker authored 
      Impact: provide useful missing info for developers

Kernel taint can occur in several situations such as warnings,
load of prorietary or staging modules, bad page, etc...

But when such taint happens, a developer might still be working on
the kernel, expecting that lockdep is still enabled. But a taint
disables lockdep without ever warning about it.
Such a kernel behaviour doesn't really help for kernel development.

This patch adds this missing warning.

Since the taint is done most of the time after the main message that
explain the real source issue, it seems safe to warn about it inside
add_taint() so that it appears at last, without hurting the main
information.

v2: Use a generic helper to disable lockdep instead of an
    open coded xchg().
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1239412638-6739-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      9eeba613
  3. 10 Apr, 2009 1 commit
    • Tejun Heo's avatar
      percpu: unbreak alpha percpu · 066123a5
      Tejun Heo authored 
      For the time being, move the generic percpu_*() accessors to
linux/percpu.h.

asm-generic/percpu.h is meant to carry generic stuff for low level
stuff - declarations, definitions and pointer offset calculation
and so on but not for generic interface.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      066123a5
  5. 09 Apr, 2009 1 commit
    • Heiko Carstens's avatar
      mutex: have non-spinning mutexes on s390 by default · 36cd3c9f
      Heiko Carstens authored 
      Impact: performance regression fix for s390

The adaptive spinning mutexes will not always do what one would expect on
virtualized architectures like s390. Especially the cpu_relax() loop in
mutex_spin_on_owner might hurt if the mutex holding cpu has been scheduled
away by the hypervisor.

We would end up in a cpu_relax() loop when there is no chance that the
state of the mutex changes until the target cpu has been scheduled again by
the hypervisor.

For that reason we should change the default behaviour to no-spin on s390.

We do have an instruction which allows to yield the current cpu in favour of
a different target cpu. Also we have an instruction which allows us to figure
out if the target cpu is physically backed.

However we need to do some performance tests until we can come up with
a solution that will do the right thing on s390.
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
LKML-Reference: <20090409184834.7a0df7b2@osiris.boeblingen.de.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      36cd3c9f
  7. 08 Apr, 2009 2 commits
  9. 07 Apr, 2009 34 commits
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