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  1. 17 12月, 2006 1 次提交
    • L
      Make workqueue bit operations work on "atomic_long_t" · a08727ba
      由 Linus Torvalds 提交于 
      On architectures where the atomicity of the bit operations is handled by
external means (ie a separate spinlock to protect concurrent accesses),
just doing a direct assignment on the workqueue data field (as done by
commit 4594bf15) can cause the
assignment to be lost due to lack of serialization with the bitops on
the same word.

So we need to serialize the assignment with the locks on those
architectures (notably older ARM chips, PA-RISC and sparc32).

So rather than using an "unsigned long", let's use "atomic_long_t",
which already has a safe assignment operation (atomic_long_set()) on
such architectures.

This requires that the atomic operations use the same atomicity locks as
the bit operations do, but that is largely the case anyway.  Sparc32
will probably need fixing.

Architectures (including modern ARM with LL/SC) that implement sane
atomic operations for SMP won't see any of this matter.

Cc: Russell King <rmk+lkml@arm.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: David Miller <davem@davemloft.com>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Linux Arch Maintainers <linux-arch@vger.kernel.org>
Cc: Andrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      a08727ba
  3. 10 12月, 2006 1 次提交
    • D
      [PATCH] WorkStruct: Use direct assignment rather than cmpxchg() · 4594bf15
      由 David Howells 提交于 
      Use direct assignment rather than cmpxchg() as the latter is unavailable
and unimplementable on some platforms and is actually unnecessary.

The use of cmpxchg() was to guard against two possibilities, neither of
which can actually occur:

 (1) The pending flag may have been unset or may be cleared.  However, given
     where it's called, the pending flag is _always_ set.  I don't think it
     can be unset whilst we're in set_wq_data().

     Once the work is enqueued to be actually run, the only way off the queue
     is for it to be actually run.

     If it's a delayed work item, then the bit can't be cleared by the timer
     because we haven't started the timer yet.  Also, the pending bit can't be
     cleared by cancelling the delayed work _until_ the work item has had its
     timer started.

 (2) The workqueue pointer might change.  This can only happen in two cases:

     (a) The work item has just been queued to actually run, and so we're
         protected by the appropriate workqueue spinlock.

     (b) A delayed work item is being queued, and so the timer hasn't been
     	 started yet, and so no one else knows about the work item or can
     	 access it (the pending bit protects us).

     Besides, set_wq_data() _sets_ the workqueue pointer unconditionally, so
     it can be assigned instead.

So, replacing the set_wq_data() with a straight assignment would be okay
in most cases.

The problem is where we end up tangling with test_and_set_bit() emulated
using spinlocks, and even then it's not a problem _provided_
test_and_set_bit() doesn't attempt to modify the word if the bit was
set.

If that's a problem, then a bitops-proofed assignment will be required -
equivalent to atomic_set() vs other atomic_xxx() ops.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      4594bf15
  5. 08 12月, 2006 4 次提交
  7. 22 11月, 2006 4 次提交
    • D
      WorkStruct: Pass the work_struct pointer instead of context data · 65f27f38
      由 David Howells 提交于 
      Pass the work_struct pointer to the work function rather than context data.
The work function can use container_of() to work out the data.

For the cases where the container of the work_struct may go away the moment the
pending bit is cleared, it is made possible to defer the release of the
structure by deferring the clearing of the pending bit.

To make this work, an extra flag is introduced into the management side of the
work_struct.  This governs auto-release of the structure upon execution.

Ordinarily, the work queue executor would release the work_struct for further
scheduling or deallocation by clearing the pending bit prior to jumping to the
work function.  This means that, unless the driver makes some guarantee itself
that the work_struct won't go away, the work function may not access anything
else in the work_struct or its container lest they be deallocated..  This is a
problem if the auxiliary data is taken away (as done by the last patch).

However, if the pending bit is *not* cleared before jumping to the work
function, then the work function *may* access the work_struct and its container
with no problems.  But then the work function must itself release the
work_struct by calling work_release().

In most cases, automatic release is fine, so this is the default.  Special
initiators exist for the non-auto-release case (ending in _NAR).
Signed-Off-By: NDavid Howells <dhowells@redhat.com>
      65f27f38
    • D
      WorkStruct: Merge the pending bit into the wq_data pointer · 365970a1
      由 David Howells 提交于 
      Reclaim a word from the size of the work_struct by folding the pending bit and
the wq_data pointer together.  This shouldn't cause misalignment problems as
all pointers should be at least 4-byte aligned.
Signed-Off-By: NDavid Howells <dhowells@redhat.com>
      365970a1
    • D
      WorkStruct: Typedef the work function prototype · 6bb49e59
      由 David Howells 提交于 
      Define a type for the work function prototype.  It's not only kept in the
work_struct struct, it's also passed as an argument to several functions.

This makes it easier to change it.
Signed-Off-By: NDavid Howells <dhowells@redhat.com>
      6bb49e59
    • D
      WorkStruct: Separate delayable and non-delayable events. · 52bad64d
      由 David Howells 提交于 
      Separate delayable work items from non-delayable work items be splitting them
into a separate structure (delayed_work), which incorporates a work_struct and
the timer_list removed from work_struct.

The work_struct struct is huge, and this limits it's usefulness.  On a 64-bit
architecture it's nearly 100 bytes in size.  This reduces that by half for the
non-delayable type of event.
Signed-Off-By: NDavid Howells <dhowells@redhat.com>
      52bad64d
  9. 29 10月, 2006 1 次提交
  11. 12 10月, 2006 1 次提交
  13. 04 10月, 2006 1 次提交
  15. 15 8月, 2006 1 次提交
  17. 01 8月, 2006 1 次提交
  19. 04 7月, 2006 1 次提交
  21. 30 6月, 2006 2 次提交
  23. 28 6月, 2006 1 次提交
    • C
      [PATCH] cpu hotplug: revert init patch submitted for 2.6.17 · 9c7b216d
      由 Chandra Seetharaman 提交于 
      In 2.6.17, there was a problem with cpu_notifiers and XFS.  I provided a
band-aid solution to solve that problem.  In the process, i undid all the
changes you both were making to ensure that these notifiers were available
only at init time (unless CONFIG_HOTPLUG_CPU is defined).

We deferred the real fix to 2.6.18.  Here is a set of patches that fixes the
XFS problem cleanly and makes the cpu notifiers available only at init time
(unless CONFIG_HOTPLUG_CPU is defined).

If CONFIG_HOTPLUG_CPU is defined then cpu notifiers are available at run
time.

This patch reverts the notifier_call changes made in 2.6.17
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      9c7b216d
  25. 26 6月, 2006 2 次提交
  27. 23 6月, 2006 1 次提交
  29. 26 4月, 2006 1 次提交
  31. 28 2月, 2006 1 次提交
    • J
      [SCSI] add execute_in_process_context() API · 1fa44eca
      由 James Bottomley 提交于 
      We have several points in the SCSI stack (primarily for our device
functions) where we need to guarantee process context, but (given the
place where the last reference was released) we cannot guarantee this.

This API gets around the issue by executing the function directly if
the caller has process context, but scheduling a workqueue to execute
in process context if the caller doesn't have it.
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>
      1fa44eca
  33. 15 1月, 2006 1 次提交
  35. 09 1月, 2006 3 次提交
    • N
      [PATCH] fix workqueue oops during cpu offline · f756d5e2
      由 Nathan Lynch 提交于 
      Use first_cpu(cpu_possible_map) for the single-thread workqueue case.  We
used to hardcode 0, but that broke on systems where !cpu_possible(0) when
workqueue_struct->cpu_workqueue_struct was changed from a static array to
alloc_percpu.

Commit id bce61dd4 ("Fix hardcoded cpu=0 in
workqueue for per_cpu_ptr() calls") fixed that for Ben's funky sparc64
system, but it regressed my Power5.  Offlining cpu 0 oopses upon the next
call to queue_work for a single-thread workqueue, because now we try to
manipulate per_cpu_ptr(wq->cpu_wq, 1), which is uninitialized.

So we need to establish an unchanging "slot" for single-thread workqueues
which will have a valid percpu allocation.  Since alloc_percpu keys off of
cpu_possible_map, which must not change after initialization, make this
slot == first_cpu(cpu_possible_map).
Signed-off-by: NNathan Lynch <ntl@pobox.com>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      f756d5e2
    • B
      [PATCH] Unchecked alloc_percpu() return in __create_workqueue() · 676121fc
      由 Ben Collins 提交于 
      __create_workqueue() not checking return of alloc_percpu()

NULL dereference was possible.
Signed-off-by: NBen Collins <bcollins@ubuntu.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      676121fc
    • C
      [PATCH] add schedule_on_each_cpu() · 15316ba8
      由 Christoph Lameter 提交于 
      swap migration's isolate_lru_page() currently uses an IPI to notify other
processors that the lru caches need to be drained if the page cannot be
found on the LRU.  The IPI interrupt may interrupt a processor that is just
processing lru requests and cause a race condition.

This patch introduces a new function run_on_each_cpu() that uses the
keventd() to run the LRU draining on each processor.  Processors disable
preemption when dealing the LRU caches (these are per processor) and thus
executing LRU draining from another process is safe.

Thanks to Lee Schermerhorn <lee.schermerhorn@hp.com> for finding this race
condition.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      15316ba8
  37. 29 11月, 2005 1 次提交
    • B
      [PATCH] Fix hardcoded cpu=0 in workqueue for per_cpu_ptr() calls · bce61dd4
      由 Ben Collins 提交于 
      Tracked this down on an Ultra Enterprise 3000.  It's a 6-way machine.  Odd
thing about this machine (and it's good for finding bugs like this) is that
the CPU id's are not 0 based.  For instance, on my machine the CPU's are
6/7/10/11/14/15.

This caused some NULL pointer dereference in kernel/workqueue.c because for
single_threaded workqueue's, it hardcoded the cpu to 0.

I changed the 0's to any_online_cpu(cpu_online_mask), which cpumask.h
claims is "First cpu in mask".  So this fits the same usage.
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      bce61dd4
  39. 07 11月, 2005 1 次提交
    • H
      [PATCH] cpu hoptlug: avoid usage of smp_processor_id() in preemptible code · a4c4af7c
      由 Heiko Carstens 提交于 
      Replace smp_processor_id() with any_online_cpu(cpu_online_map) in order to
avoid lots of "BUG: using smp_processor_id() in preemptible [00000001]
code:..." messages in case taking a cpu online fails.

All the traces start at the last notifier_call_chain(...) in kernel/cpu.c.
Since we hold the cpu_control semaphore it shouldn't be any problem to access
cpu_online_map.

The reason why cpu_up failed is simply that the cpu that was supposed to be
taken online wasn't even there.  That is because on s390 we never know when a
new cpu comes and therefore cpu_possible_map consists of only ones and doesn't
reflect reality.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      a4c4af7c
  41. 31 10月, 2005 1 次提交
  43. 08 9月, 2005 2 次提交
  45. 11 8月, 2005 1 次提交
    • J
      [PATCH] remove name length check in a workqueue · 60686744
      由 James Bottomley 提交于 
      We have a chek in there to make sure that the name won't overflow
task_struct.comm[], but it's triggering for scsi with lots of HBAs, only
scsi is using single-threaded workqueues which don't append the "/%d"
anyway.

All too hard.  Just kill the BUG_ON.

Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

[ kthread_create() uses vsnprintf() and limits the thing, so no
  actual overflow can actually happen regardless ]
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      60686744
  47. 17 4月, 2005 2 次提交
    • J
      [PATCH] re-export cancel_rearming_delayed_workqueue · 81ddef77
      由 James Bottomley 提交于 
      This was unexported by Arjan because we have no current users.

However, during a conversion from tasklets to workqueues of the parisc led
functions, we ran across a case where this was needed.  In particular, the
open coded equivalent of cancel_rearming_delayed_workqueue was implemented
incorrectly, which is, I think, all the evidence necessary that this is a
useful API.
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      81ddef77
    • L
      Linux-2.6.12-rc2 · 1da177e4
      由 Linus Torvalds 提交于 
      Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
      1da177e4