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: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
The raw_spin* namespace was taken by lockdep for the architecture
specific implementations. raw_spin_* would be the ideal name space for
the spinlocks which are not converted to sleeping locks in preempt-rt.
Linus suggested to convert the raw_ to arch_ locks and cleanup the
name space instead of using an artifical name like core_spin,
atomic_spin or whatever
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
We need to have a stronger barrier between releasing the lock and
checking for any waiting spinners. A compiler barrier is not sufficient
because the CPU's ordering rules do not prevent the read xl->spinners
from happening before the unlock assignment, as they are different
memory locations.
We need to have an explicit barrier to enforce the write-read ordering
to different memory locations.
Because of it, I can't bring up > 4 HVM guests on one SMP machine.
[ Code and commit comments expanded -J ]
[ Impact: avoid deadlock when using Xen PV spinlocks ]
Signed-off-by: Yang Xiaowei <xiaowei.yang@intel.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Where possible we enable interrupts while waiting for a spinlock to
become free, in order to reduce big latency spikes in interrupt handling.
However, at present if we manage to pick up the spinlock just before
blocking, we'll end up holding the lock with interrupts enabled for a
while. This will cause a deadlock if we recieve an interrupt in that
window, and the interrupt handler tries to take the lock too.
Solve this by shrinking the interrupt-enabled region to just around the
blocking call.
[ Impact: avoid race/deadlock when using Xen PV spinlocks ]
Reported-by: "Yang, Xiaowei" <xiaowei.yang@intel.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
based on Eric's patch ...
together mold it with dyn_array for irq_desc, will allcate kstat_irqs for
nr_irq_desc alltogether if needed. -- at that point nr_cpus is known already.
v2: make sure system without generic_hardirqs works they don't have irq_desc
v3: fix merging
v4: [mingo@elte.hu] fix typo
[ mingo@elte.hu ] irq: build fix
fix:
arch/x86/xen/spinlock.c: In function 'xen_spin_lock_slow':
arch/x86/xen/spinlock.c:90: error: 'struct kernel_stat' has no member named 'irqs'
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Note the changes from 2.6.18-xen CPU hotplugging:
A vcpu_down request from the remote admin via Xenbus both hotunplugs the
CPU, and disables it by removing it from the cpu_present map, and removing
its entry in /sys.
A vcpu_up request from the remote admin only re-enables the CPU, and does
not immediately bring the CPU up. A udev event is emitted, which can be
caught by the user if he wishes to automatically re-up CPUs when available,
or implement a more complex policy.
Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Measure how long spinlocks spend blocked. Also rename some fields to
be more consistent.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If spin_lock is called in an interrupts-enabled context, we can safely
enable interrupts while spinning. We don't bother for the actual spin
loop, but if we timeout and fall back to blocking, it's definitely
worthwhile enabling interrupts if possible.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add support for exporting statistics on mmu updates, multicall
batching and pv spinlocks into debugfs. The base path is xen/ and
each subsystem adds its own directory: mmu, multicalls, spinlocks.
In each directory, writing 1 to "zero_stats" will cause the
corresponding stats to be zeroed the next time they're updated.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
A spinlock can be interrupted while spinning, so make sure we preserve
the previous lock of interest if we're taking a lock from within an
interrupt handler.
We also need to deal with the case where the blocking path gets
interrupted between testing to see if the lock is free and actually
blocking. If we get interrupted there and end up in the state where
the lock is free but the irq isn't pending, then we'll block
indefinitely in the hypervisor. This fix is to make sure that any
nested lock-takers will always leave the irq pending if there's any
chance the outer lock became free.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
ftrace requires certain low-level code, like spinlocks and timestamps,
to be compiled without -pg in order to avoid infinite recursion. This
patch splits out the core paravirt spinlocks and the Xen spinlocks
into separate files which can be compiled without -pg.
Also do xen/time.c while we're about it. As a result, we can now use
ftrace within a Xen domain.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
