linux-toradex.git/kernel/workqueue.c, branch v3.3.5

Block: use a freezable workqueue for disk-event polling

2012-03-02T09:51:00+00:00

This patch (as1519) fixes a bug in the block layer's disk-events
polling.  The polling is done by a work routine queued on the
system_nrt_wq workqueue.  Since that workqueue isn't freezable, the
polling continues even in the middle of a system sleep transition.

Obviously, polling a suspended drive for media changes and such isn't
a good thing to do; in the case of USB mass-storage devices it can
lead to real problems requiring device resets and even re-enumeration.

The patch fixes things by creating a new system-wide, non-reentrant,
freezable workqueue and using it for disk-events polling.

Signed-off-by: Alan Stern 
CC: 
Acked-by: Tejun Heo 
Acked-by: Rafael J. Wysocki 
Signed-off-by: Jens Axboe

workqueue: make alloc_workqueue() take printf fmt and args for name

2012-01-11T00:30:54+00:00

alloc_workqueue() currently expects the passed in @name pointer to remain
accessible.  This is inconvenient and a bit silly given that the whole wq
is being dynamically allocated.  This patch updates alloc_workqueue() and
friends to take printf format string instead of opaque string and matching
varargs at the end.  The name is allocated together with the wq and
formatted.

alloc_ordered_workqueue() is converted to a macro to unify varargs
handling with alloc_workqueue(), and, while at it, add comment to
alloc_workqueue().

None of the current in-kernel users pass in string with '%' as constant
name and this change shouldn't cause any problem.

[akpm@linux-foundation.org: use __printf]
Signed-off-by: Tejun Heo 
Suggested-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel: Map most files to use export.h instead of module.h

2011-10-31T13:20:12+00:00

The changed files were only including linux/module.h for the
EXPORT_SYMBOL infrastructure, and nothing else.  Revector them
onto the isolated export header for faster compile times.

Nothing to see here but a whole lot of instances of:

  -#include 
  +#include 

This commit is only changing the kernel dir; next targets
will probably be mm, fs, the arch dirs, etc.

Signed-off-by: Paul Gortmaker

workqueue: lock cwq access in drain_workqueue

2011-09-15T01:09:38+00:00

Take cwq->gcwq->lock to avoid racing between drain_workqueue checking to
make sure the workqueues are empty and cwq_dec_nr_in_flight decrementing
and then incrementing nr_active when it activates a delayed work.

We discovered this when a corner case in one of our drivers resulted in
us trying to destroy a workqueue in which the remaining work would
always requeue itself again in the same workqueue.  We would hit this
race condition and trip the BUG_ON on workqueue.c:3080.

Signed-off-by: Thomas Tuttle 
Acked-by: Tejun Heo 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-3.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2011-07-22T22:07:15+00:00

* 'for-3.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: separate out drain_workqueue() from destroy_workqueue()
  workqueue: remove cancel_rearming_delayed_work[queue]()

Merge branch 'for-2.6.40' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

2011-05-24T18:53:42+00:00

* 'for-2.6.40' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
  percpu: Unify input section names
  percpu: Avoid extra NOP in percpu_cmpxchg16b_double
  percpu: Cast away printk format warning
  percpu: Always align percpu output section to PAGE_SIZE

Fix up fairly trivial conflict in arch/x86/include/asm/percpu.h as per Tejun

workqueue: separate out drain_workqueue() from destroy_workqueue()

2011-05-20T11:54:46+00:00

There are users which want to drain workqueues without destroying it.
Separate out drain functionality from destroy_workqueue() into
drain_workqueue() and make it accessible to workqueue users.

To guarantee forward-progress, only chain queueing is allowed while
drain is in progress.  If a new work item which isn't chained from the
running or pending work items is queued while draining is in progress,
WARN_ON_ONCE() is triggered.

Signed-off-by: Tejun Heo 
Cc: James Bottomley

workqueue: fix deadlock in worker_maybe_bind_and_lock()

2011-04-29T16:08:37+00:00

If a rescuer and stop_machine() bringing down a CPU race with each
other, they may deadlock on non-preemptive kernel.  The CPU won't
accept a new task, so the rescuer can't migrate to the target CPU,
while stop_machine() can't proceed because the rescuer is holding one
of the CPU retrying migration.  GCWQ_DISASSOCIATED is never cleared
and worker_maybe_bind_and_lock() retries indefinitely.

This problem can be reproduced semi reliably while the system is
entering suspend.

 http://thread.gmane.org/gmane.linux.kernel/1122051

A lot of kudos to Thilo-Alexander for reporting this tricky issue and
painstaking testing.

stable: This affects all kernels with cmwq, so all kernels since and
        including v2.6.36 need this fix.

Signed-off-by: Tejun Heo 
Reported-by: Thilo-Alexander Ginkel 
Tested-by: Thilo-Alexander Ginkel 
Cc: stable@kernel.org

percpu: Always align percpu output section to PAGE_SIZE

2011-03-24T17:50:09+00:00

Percpu allocator honors alignment request upto PAGE_SIZE and both the
percpu addresses in the percpu address space and the translated kernel
addresses should be aligned accordingly.  The calculation of the
former depends on the alignment of percpu output section in the kernel
image.

The linker script macros PERCPU_VADDR() and PERCPU() are used to
define this output section and the latter takes @align parameter.
Several architectures are using @align smaller than PAGE_SIZE breaking
percpu memory alignment.

This patch removes @align parameter from PERCPU(), renames it to
PERCPU_SECTION() and makes it always align to PAGE_SIZE.  While at it,
add PCPU_SETUP_BUG_ON() checks such that alignment problems are
reliably detected and remove percpu alignment comment recently added
in workqueue.c as the condition would trigger BUG way before reaching
there.

For um, this patch raises the alignment of percpu area.  As the area
is in .init, there shouldn't be any noticeable difference.

This problem was discovered by David Howells while debugging boot
failure on mn10300.

Signed-off-by: Tejun Heo 
Acked-by: Mike Frysinger 
Cc: uclinux-dist-devel@blackfin.uclinux.org
Cc: David Howells 
Cc: Jeff Dike 
Cc: user-mode-linux-devel@lists.sourceforge.net

kthread: use kthread_create_on_node()

2011-03-23T00:44:01+00:00

ksoftirqd, kworker, migration, and pktgend kthreads can be created with
kthread_create_on_node(), to get proper NUMA affinities for their stack and
task_struct.

Signed-off-by: Eric Dumazet 
Acked-by: David S. Miller 
Reviewed-by: Andi Kleen 
Acked-by: Rusty Russell 
Acked-by: Tejun Heo 
Cc: Tony Luck 
Cc: Fenghua Yu 
Cc: David Howells 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds