linux-toradex.git/block/deadline-iosched.c, branch v3.10.9

elevator: Fix a race in elevator switching

2013-08-20T15:43:03+00:00

commit d50235b7bc3ee0a0427984d763ea7534149531b4 upstream.

There's a race between elevator switching and normal io operation.
    Because the allocation of struct elevator_queue and struct elevator_data
    don't in a atomic operation.So there are have chance to use NULL
    ->elevator_data.
    For example:
        Thread A:                               Thread B
        blk_queu_bio                            elevator_switch
        spin_lock_irq(q->queue_block)           elevator_alloc
        elv_merge                               elevator_init_fn

    Because call elevator_alloc, it can't hold queue_lock and the
    ->elevator_data is NULL.So at the same time, threadA call elv_merge and
    nedd some info of elevator_data.So the crash happened.

    Move the elevator_alloc into func elevator_init_fn, it make the
    operations in a atomic operation.

    Using the follow method can easy reproduce this bug
    1:dd if=/dev/sdb of=/dev/null
    2:while true;do echo noop > scheduler;echo deadline > scheduler;done

    The test method also use this method.

Signed-off-by: Jianpeng Ma 
Signed-off-by: Jens Axboe 
Cc: Jonghwan Choi 
Signed-off-by: Greg Kroah-Hartman

block: Add bio_end_sector()

2013-03-23T21:15:29+00:00

Just a little convenience macro - main reason to add it now is preparing
for immutable bio vecs, it'll reduce the size of the patch that puts
bi_sector/bi_size/bi_idx into a struct bvec_iter.

Signed-off-by: Kent Overstreet 
CC: Jens Axboe 
CC: Lars Ellenberg 
CC: Jiri Kosina 
CC: Alasdair Kergon 
CC: dm-devel@redhat.com
CC: Neil Brown 
CC: Martin Schwidefsky 
CC: Heiko Carstens 
CC: linux-s390@vger.kernel.org
CC: Chris Mason 
CC: Steven Whitehouse 
Acked-by: Steven Whitehouse

deadline: Allow 0ms deadline latency, increase the read speed

2012-12-09T18:19:23+00:00

Change a timer compare from after to after-equals, thus allowing
0 timeout and making deadline schedule FIFO.

Signed-off-by: xiaobing tu 
Signed-off-by: Jens Axboe

elevator: make elevator_init_fn() return 0/-errno

2012-03-06T20:27:21+00:00

elevator_ops->elevator_init_fn() has a weird return value.  It returns
a void * which the caller should assign to q->elevator->elevator_data
and %NULL return denotes init failure.

Update such that it returns integer 0/-errno and sets elevator_data
directly as necessary.

This makes the interface more conventional and eases further cleanup.

Signed-off-by: Tejun Heo 
Cc: Vivek Goyal 
Signed-off-by: Jens Axboe

block, cfq: move icq cache management to block core

2011-12-13T23:33:42+00:00

Let elevators set ->icq_size and ->icq_align in elevator_type and
elv_register() and elv_unregister() respectively create and destroy
kmem_cache for icq.

* elv_register() now can return failure.  All callers updated.

* icq caches are automatically named "ELVNAME_io_cq".

* cfq_slab_setup/kill() are collapsed into cfq_init/exit().

* While at it, minor indentation change for iosched_cfq.elevator_name
  for consistency.

This will help moving icq management to block core.  This doesn't
introduce any functional change.

Signed-off-by: Tejun Heo 
Signed-off-by: Jens Axboe

iosched: prevent aliased requests from starving other I/O

2011-06-02T19:19:05+00:00

Hi, Jens,

If you recall, I posted an RFC patch for this back in July of last year:
http://lkml.org/lkml/2010/7/13/279

The basic problem is that a process can issue a never-ending stream of
async direct I/Os to the same sector on a device, thus starving out
other I/O in the system (due to the way the alias handling works in both
cfq and deadline).  The solution I proposed back then was to start
dispatching from the fifo after a certain number of aliases had been
dispatched.  Vivek asked why we had to treat aliases differently at all,
and I never had a good answer.  So, I put together a simple patch which
allows aliases to be added to the rb tree (it adds them to the right,
though that doesn't matter as the order isn't guaranteed anyway).  I
think this is the preferred solution, as it doesn't break up time slices
in CFQ or batches in deadline.  I've tested it, and it does solve the
starvation issue.  Let me know what you think.

Cheers,
Jeff

Signed-off-by: Jeff Moyer 
Signed-off-by: Jens Axboe

block: remove per-queue plugging

2011-03-10T07:52:07+00:00

Code has been converted over to the new explicit on-stack plugging,
and delay users have been converted to use the new API for that.
So lets kill off the old plugging along with aops->sync_page().

Signed-off-by: Jens Axboe

block: convert to pos and nr_sectors accessors

2009-05-11T07:50:54+00:00

With recent cleanups, there is no place where low level driver
directly manipulates request fields.  This means that the 'hard'
request fields always equal the !hard fields.  Convert all
rq->sectors, nr_sectors and current_nr_sectors references to
accessors.

While at it, drop superflous blk_rq_pos() < 0 test in swim.c.

[ Impact: use pos and nr_sectors accessors ]

Signed-off-by: Tejun Heo 
Acked-by: Geert Uytterhoeven 
Tested-by: Grant Likely 
Acked-by: Grant Likely 
Tested-by: Adrian McMenamin 
Acked-by: Adrian McMenamin 
Acked-by: Mike Miller 
Cc: James Bottomley 
Cc: Bartlomiej Zolnierkiewicz 
Cc: Borislav Petkov 
Cc: Sergei Shtylyov 
Cc: Eric Moore 
Cc: Alan Stern 
Cc: FUJITA Tomonori 
Cc: Pete Zaitcev 
Cc: Stephen Rothwell 
Cc: Paul Clements 
Cc: Tim Waugh 
Cc: Jeff Garzik 
Cc: Jeremy Fitzhardinge 
Cc: Alex Dubov 
Cc: David Woodhouse 
Cc: Martin Schwidefsky 
Cc: Dario Ballabio 
Cc: David S. Miller 
Cc: Rusty Russell 
Cc: unsik Kim 
Cc: Laurent Vivier 
Signed-off-by: Jens Axboe

block: get rid of elevator_t typedef

2008-12-29T07:29:50+00:00

Just use struct elevator_queue everywhere instead.

Signed-off-by: Jens Axboe

deadline-iosched: non-functional fixes

2008-10-09T06:56:03+00:00

* convert goto to simpler while loop;
 * use rq_end_sector() instead of computing manually;
 * fix false comments;
 * remove spurious whitespace;
 * convert rq_rb_root macro to an inline function.

Signed-off-by: Aaron Carroll 
Signed-off-by: Jens Axboe