29 Dec, 2011

1 commit

  • Commit 5e081591 "block: warn if tag is greater than real_max_depth"
    cleaned up blk_queue_end_tag() to warn when the tag is truly invalid
    (greater than real_max_depth). However, it changed behavior in the tag <
    max_depth case to not end the request. Leading to triggering of
    BUG_ON(blk_queued_rq(rq)) in the request completion path:

    http://marc.info/?l=linux-kernel&m=132204370518629&w=2

    In order to allow blk_queue_resize_tags() to shrink the tag space
    blk_queue_end_tag() must always complete tags with a value less than
    real_max_depth regardless of the current max_depth. The comment about
    "handling the shrink case" seems to be what prompted changes in this
    space, so remove it and BUG on all invalid tags (made even simpler by
    Matthew's suggestion to use an unsigned compare).

    Signed-off-by: Dan Williams
    Cc: Tao Ma
    Cc: Matthew Wilcox
    Reported-by: Meelis Roos
    Reported-by: Ed Nadolski
    Cc: Tejun Heo
    Signed-off-by: Andrew Morton
    Signed-off-by: Jens Axboe

    Dan Williams
     

25 Oct, 2011

1 commit


30 Mar, 2010

1 commit

  • …it slab.h inclusion from percpu.h

    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>

    Tejun Heo
     

07 Oct, 2009

1 commit


20 May, 2009

1 commit


11 May, 2009

1 commit

  • Till now block layer allowed two separate modes of request execution.
    A request is always acquired from the request queue via
    elv_next_request(). After that, drivers are free to either dequeue it
    or process it without dequeueing. Dequeue allows elv_next_request()
    to return the next request so that multiple requests can be in flight.

    Executing requests without dequeueing has its merits mostly in
    allowing drivers for simpler devices which can't do sg to deal with
    segments only without considering request boundary. However, the
    benefit this brings is dubious and declining while the cost of the API
    ambiguity is increasing. Segment based drivers are usually for very
    old or limited devices and as converting to dequeueing model isn't
    difficult, it doesn't justify the API overhead it puts on block layer
    and its more modern users.

    Previous patches converted all block low level drivers to dequeueing
    model. This patch completes the API transition by...

    * renaming elv_next_request() to blk_peek_request()

    * renaming blkdev_dequeue_request() to blk_start_request()

    * adding blk_fetch_request() which is combination of peek and start

    * disallowing completion of queued (not started) requests

    * applying new API to all LLDs

    Renamings are for consistency and to break out of tree code so that
    it's apparent that out of tree drivers need updating.

    [ Impact: block request issue API cleanup, no functional change ]

    Signed-off-by: Tejun Heo
    Cc: Rusty Russell
    Cc: James Bottomley
    Cc: Mike Miller
    Cc: unsik Kim
    Cc: Paul Clements
    Cc: Tim Waugh
    Cc: Geert Uytterhoeven
    Cc: David S. Miller
    Cc: Laurent Vivier
    Cc: Jeff Garzik
    Cc: Jeremy Fitzhardinge
    Cc: Grant Likely
    Cc: Adrian McMenamin
    Cc: Stephen Rothwell
    Cc: Bartlomiej Zolnierkiewicz
    Cc: Borislav Petkov
    Cc: Sergei Shtylyov
    Cc: Alex Dubov
    Cc: Pierre Ossman
    Cc: David Woodhouse
    Cc: Markus Lidel
    Cc: Stefan Weinhuber
    Cc: Martin Schwidefsky
    Cc: Pete Zaitcev
    Cc: FUJITA Tomonori
    Signed-off-by: Jens Axboe

    Tejun Heo
     

29 Dec, 2008

1 commit


09 Oct, 2008

2 commits


27 Aug, 2008

1 commit


07 May, 2008

1 commit

  • For most initialization purposes, calling blk_queue_init_tags() without
    the queue lock held is OK. Only if called for resizing an existing map
    must the lock be held. Ditto for tag cleanup, the maps are reference
    counted.

    So switch the general queue flag setting to the unlocked variant, but
    retain the locked variant for resizing.

    Signed-off-by: Jens Axboe

    Jens Axboe
     

01 May, 2008

1 commit


29 Apr, 2008

1 commit


04 Mar, 2008

1 commit


01 Feb, 2008

1 commit


30 Jan, 2008

1 commit