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  1. 18 9月, 2010 1 次提交
  3. 07 9月, 2010 1 次提交
  5. 05 9月, 2010 1 次提交
    • M
      cgroups: fix API thinko · 73457f0f
      由 Michael S. Tsirkin 提交于 
      cgroup_attach_task_current_cg API that have upstream is backwards: we
really need an API to attach to the cgroups from another process A to
the current one.

In our case (vhost), a priveledged user wants to attach it's task to cgroups
from a less priveledged one, the API makes us run it in the other
task's context, and this fails.

So let's make the API generic and just pass in 'from' and 'to' tasks.
Add an inline wrapper for cgroup_attach_task_current_cg to avoid
breaking bisect.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NPaul Menage <menage@google.com>
      73457f0f
  7. 04 9月, 2010 1 次提交
  9. 01 9月, 2010 1 次提交
  11. 29 8月, 2010 1 次提交
  13. 28 8月, 2010 1 次提交
  15. 27 8月, 2010 1 次提交
  17. 25 8月, 2010 4 次提交
    • T
      workqueue: fix cwq->nr_active underflow · 8a2e8e5d
      由 Tejun Heo 提交于 
      cwq->nr_active is used to keep track of how many work items are active
for the cpu workqueue, where 'active' is defined as either pending on
global worklist or executing.  This is used to implement the
max_active limit and workqueue freezing.  If a work item is queued
after nr_active has already reached max_active, the work item doesn't
increment nr_active and is put on the delayed queue and gets activated
later as previous active work items retire.

try_to_grab_pending() which is used in the cancellation path
unconditionally decremented nr_active whether the work item being
cancelled is currently active or delayed, so cancelling a delayed work
item makes nr_active underflow.  This breaks max_active enforcement
and triggers BUG_ON() in destroy_workqueue() later on.

This patch fixes this bug by adding a flag WORK_STRUCT_DELAYED, which
is set while a work item in on the delayed list and making
try_to_grab_pending() decrement nr_active iff the work item is
currently active.

The addition of the flag enlarges cwq alignment to 256 bytes which is
getting a bit too large.  It's scheduled to be reduced back to 128
bytes by merging WORK_STRUCT_PENDING and WORK_STRUCT_CWQ in the next
devel cycle.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NJohannes Berg <johannes@sipsolutions.net>
      8a2e8e5d
    • R
      ACPI/PCI: Negotiate _OSC control bits before requesting them · 75fb60f2
      由 Rafael J. Wysocki 提交于 
      It is possible that the BIOS will not grant control of all _OSC
features requested via acpi_pci_osc_control_set(), so it is
recommended to negotiate the final set of _OSC features with the
query flag set before calling _OSC to request control of these
features.

To implement it, rework acpi_pci_osc_control_set() so that the caller
can specify the mask of _OSC control bits to negotiate and the mask
of _OSC control bits that are absolutely necessary to it.  Then,
acpi_pci_osc_control_set() will run _OSC queries in a loop until
the mask of _OSC control bits returned by the BIOS is equal to the
mask passed to it.  Also, before running the _OSC request
acpi_pci_osc_control_set() will check if the caller's required
control bits are present in the final mask.

Using this mechanism we will be able to avoid situations in which the
BIOS doesn't grant control of certain _OSC features, because they
depend on some other _OSC features that have not been requested.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
      75fb60f2
    • L
      guard page for stacks that grow upwards · 8ca3eb08
      由 Luck, Tony 提交于 
      pa-risc and ia64 have stacks that grow upwards. Check that
they do not run into other mappings. By making VM_GROWSUP
0x0 on architectures that do not ever use it, we can avoid
some unpleasant #ifdefs in check_stack_guard_page().
Signed-off-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8ca3eb08
    • T
      workqueue: improve destroy_workqueue() debuggability · e41e704b
      由 Tejun Heo 提交于 
      Now that the worklist is global, having works pending after wq
destruction can easily lead to oops and destroy_workqueue() have
several BUG_ON()s to catch these cases.  Unfortunately, BUG_ON()
doesn't tell much about how the work became pending after the final
flush_workqueue().

This patch adds WQ_DYING which is set before the final flush begins.
If a work is requested to be queued on a dying workqueue,
WARN_ON_ONCE() is triggered and the request is ignored.  This clearly
indicates which caller is trying to queue a work on a dying workqueue
and keeps the system working in most cases.

Locking rule comment is updated such that the 'I' rule includes
modifying the field from destruction path.
Signed-off-by: NTejun Heo <tj@kernel.org>
      e41e704b
  19. 24 8月, 2010 2 次提交
  21. 23 8月, 2010 2 次提交
    • C
      header: fix broken headers for user space · 09cd2b99
      由 Changli Gao 提交于 
      __packed is only defined in kernel space, so we should use
__attribute__((packed)) for the code shared between kernel and user space.

Two __attribute() annotations are replaced with __attribute__() too.
Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      09cd2b99
    • E
      fanotify: flush outstanding perm requests on group destroy · 2eebf582
      由 Eric Paris 提交于 
      When an fanotify listener is closing it may cause a deadlock between the
listener and the original task doing an fs operation.  If the original task
is waiting for a permissions response it will be holding the srcu lock.  The
listener cannot clean up and exit until after that srcu lock is syncronized.
Thus deadlock.  The fix introduced here is to stop accepting new permissions
events when a listener is shutting down and to grant permission for all
outstanding events.  Thus the original task will eventually release the srcu
lock and the listener can complete shutdown.
Reported-by: NAndreas Gruenbacher <agruen@suse.de>
Cc: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: NEric Paris <eparis@redhat.com>
      2eebf582
  23. 21 8月, 2010 5 次提交
  25. 20 8月, 2010 1 次提交
  27. 19 8月, 2010 2 次提交
  29. 18 8月, 2010 10 次提交
    • N
      fs: scale files_lock · 6416ccb7
      由 Nick Piggin 提交于 
      fs: scale files_lock

Improve scalability of files_lock by adding per-cpu, per-sb files lists,
protected with an lglock. The lglock provides fast access to the per-cpu lists
to add and remove files. It also provides a snapshot of all the per-cpu lists
(although this is very slow).

One difficulty with this approach is that a file can be removed from the list
by another CPU. We must track which per-cpu list the file is on with a new
variale in the file struct (packed into a hole on 64-bit archs). Scalability
could suffer if files are frequently removed from different cpu's list.

However loads with frequent removal of files imply short interval between
adding and removing the files, and the scheduler attempts to avoid moving
processes too far away. Also, even in the case of cross-CPU removal, the
hardware has much more opportunity to parallelise cacheline transfers with N
cachelines than with 1.

A worst-case test of 1 CPU allocating files subsequently being freed by N CPUs
degenerates to contending on a single lock, which is no worse than before. When
more than one CPU are allocating files, even if they are always freed by
different CPUs, there will be more parallelism than the single-lock case.

Testing results:

On a 2 socket, 8 core opteron, I measure the number of times the lock is taken
to remove the file, the number of times it is removed by the same CPU that
added it, and the number of times it is removed by the same node that added it.

Booting:    locks=  25049 cpu-hits=  23174 (92.5%) node-hits=  23945 (95.6%)
kbuild -j16 locks=2281913 cpu-hits=2208126 (96.8%) node-hits=2252674 (98.7%)
dbench 64   locks=4306582 cpu-hits=4287247 (99.6%) node-hits=4299527 (99.8%)

So a file is removed from the same CPU it was added by over 90% of the time.
It remains within the same node 95% of the time.

Tim Chen ran some numbers for a 64 thread Nehalem system performing a compile.

                throughput
2.6.34-rc2      24.5
+patch          24.9

                us      sys     idle    IO wait (in %)
2.6.34-rc2      51.25   28.25   17.25   3.25
+patch          53.75   18.5    19      8.75

So significantly less CPU time spent in kernel code, higher idle time and
slightly higher throughput.

Single threaded performance difference was within the noise of microbenchmarks.
That is not to say penalty does not exist, the code is larger and more memory
accesses required so it will be slightly slower.

Cc: linux-kernel@vger.kernel.org
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      6416ccb7
    • N
      lglock: introduce special lglock and brlock spin locks · 2dc91abe
      由 Nick Piggin 提交于 
      lglock: introduce special lglock and brlock spin locks

This patch introduces "local-global" locks (lglocks). These can be used to:

- Provide fast exclusive access to per-CPU data, with exclusive access to
  another CPU's data allowed but possibly subject to contention, and to provide
  very slow exclusive access to all per-CPU data.
- Or to provide very fast and scalable read serialisation, and to provide
  very slow exclusive serialisation of data (not necessarily per-CPU data).

Brlocks are also implemented as a short-hand notation for the latter use
case.

Thanks to Paul for local/global naming convention.

Cc: linux-kernel@vger.kernel.org
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      2dc91abe
    • N
      tty: fix fu_list abuse · d996b62a
      由 Nick Piggin 提交于 
      tty: fix fu_list abuse

tty code abuses fu_list, which causes a bug in remount,ro handling.

If a tty device node is opened on a filesystem, then the last link to the inode
removed, the filesystem will be allowed to be remounted readonly. This is
because fs_may_remount_ro does not find the 0 link tty inode on the file sb
list (because the tty code incorrectly removed it to use for its own purpose).
This can result in a filesystem with errors after it is marked "clean".

Taking idea from Christoph's initial patch, allocate a tty private struct
at file->private_data and put our required list fields in there, linking
file and tty. This makes tty nodes behave the same way as other device nodes
and avoid meddling with the vfs, and avoids this bug.

The error handling is not trivial in the tty code, so for this bugfix, I take
the simple approach of using __GFP_NOFAIL and don't worry about memory errors.
This is not a problem because our allocator doesn't fail small allocs as a rule
anyway. So proper error handling is left as an exercise for tty hackers.

[ Arguably filesystem's device inode would ideally be divorced from the
driver's pseudo inode when it is opened, but in practice it's not clear whether
that will ever be worth implementing. ]

Cc: linux-kernel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      d996b62a
    • N
      fs: cleanup files_lock locking · ee2ffa0d
      由 Nick Piggin 提交于 
      fs: cleanup files_lock locking

Lock tty_files with a new spinlock, tty_files_lock; provide helpers to
manipulate the per-sb files list; unexport the files_lock spinlock.

Cc: linux-kernel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      ee2ffa0d
    • N
      fs: fs_struct rwlock to spinlock · 2a4419b5
      由 Nick Piggin 提交于 
      fs: fs_struct rwlock to spinlock

struct fs_struct.lock is an rwlock with the read-side used to protect root and
pwd members while taking references to them. Taking a reference to a path
typically requires just 2 atomic ops, so the critical section is very small.
Parallel read-side operations would have cacheline contention on the lock, the
dentry, and the vfsmount cachelines, so the rwlock is unlikely to ever give a
real parallelism increase.

Replace it with a spinlock to avoid one or two atomic operations in typical
path lookup fastpath.
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      2a4419b5
    • C
      remove SWRITE* I/O types · 9cb569d6
      由 Christoph Hellwig 提交于 
      These flags aren't real I/O types, but tell ll_rw_block to always
lock the buffer instead of giving up on a failed trylock.

Instead add a new write_dirty_buffer helper that implements this semantic
and use it from the existing SWRITE* callers.  Note that the ll_rw_block
code had a bug where it didn't promote WRITE_SYNC_PLUG properly, which
this patch fixes.

In the ufs code clean up the helper that used to call ll_rw_block
to mirror sync_dirty_buffer, which is the function it implements for
compound buffers.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      9cb569d6
    • C
      kill BH_Ordered flag · 87e99511
      由 Christoph Hellwig 提交于 
      Instead of abusing a buffer_head flag just add a variant of
sync_dirty_buffer which allows passing the exact type of write
flag required.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      87e99511
    • E
      spi.h: missing kernel-doc notation, please fix · 5c79a5ae
      由 Ernst Schwab 提交于 
      Added comments in kernel-doc notation for previously added struct fields.
Signed-off-by: NErnst Schwab <eschwab@online.de>
Acked-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>
      5c79a5ae
    • D
      Make do_execve() take a const filename pointer · d7627467
      由 David Howells 提交于 
      Make do_execve() take a const filename pointer so that kernel_execve() compiles
correctly on ARM:

arch/arm/kernel/sys_arm.c:88: warning: passing argument 1 of 'do_execve' discards qualifiers from pointer target type

This also requires the argv and envp arguments to be consted twice, once for
the pointer array and once for the strings the array points to.  This is
because do_execve() passes a pointer to the filename (now const) to
copy_strings_kernel().  A simpler alternative would be to cast the filename
pointer in do_execve() when it's passed to copy_strings_kernel().

do_execve() may not change any of the strings it is passed as part of the argv
or envp lists as they are some of them in .rodata, so marking these strings as
const should be fine.

Further kernel_execve() and sys_execve() need to be changed to match.

This has been test built on x86_64, frv, arm and mips.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Tested-by: NRalf Baechle <ralf@linux-mips.org>
Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d7627467
    • R
      VIDEO: amba clcd: don't disable an already disabled clock · 99c796df
      由 Russell King 提交于 
      Fix the clock enable/disable tracking in the AMBA CLCD driver so
that the driver doesn't try to disable an already disabled clock,
thereby causing the clock (if shared) to become unbalanced.

This resolves a problem with CLCD on LPC32xx ARM platforms.
Reported-by: NKevin Wells <wellsk40@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      99c796df
  31. 15 8月, 2010 2 次提交
  33. 14 8月, 2010 4 次提交