1. 21 Sep, 2003 40 commits
    • Andrew Morton's avatar
      [PATCH] bio_dirty_fn() page leak fix · 69d85819
      Andrew Morton authored
      bio_dirty_fn() needs to drop its ref against each remaining page in the BIO
      before releasing the BIO.
      69d85819
    • Andrew Morton's avatar
      [PATCH] deadline insert_here fix · 1669e6e9
      Andrew Morton authored
      From: Nick Piggin <piggin@cyberone.com.au>
      
      Fix fallout from Jens' insert_here removal.  Without it its possible that a
      request on the dispatch list is on the merge hash as well which is bad.  I
      don't _think_ this would happen in any code paths, but I haven't looked too
      closely.  It makes the API a bit less fragile anyway.
      1669e6e9
    • Andrew Morton's avatar
      [PATCH] x445: setup_ioapic_ids_from_mpc fix · 36a57256
      Andrew Morton authored
      From: James Cleverdon <jamesclv@us.ibm.com>
      
      32-way IBM x445s will have I/O xAPICs with IDs greater than 0xF (0x8 to 0xE
      isn't enough).  This breaks the code in setup_ioapic_ids_from_mpc.
      However, the entire unique ID check is unnecessary.  Only I/O APICs using
      the serial APIC bus need the unique numbers.  Those sending messages
      through the system bus simply don't use them.
      36a57256
    • Andrew Morton's avatar
      [PATCH] Incorrect value for SIGRTMAX · 58e1dd1e
      Andrew Morton authored
      From: Corey Minyard <minyard@acm.org>
      
      I was having a problem with signals with POSIX timers, and it turns out 
      that the value of SIGRTMAX is incorrect.  Remember that there is no
      signal 0, so the signals should go from 1-_NSIG.  However, SIGRTMAX is
      defined as (_NSIG-1) in all architectures.  The following patch fixes this.
      
      This define is only used in drivers/usb/core/devio.c and 
      kernel/posix-timers.c, and both are incorrect without this fix.  There's
      also no check for zero in posix-timers.c, that fix is part of the diff.
      
      Also, shouldn't do_sigaction() use this value instead of _NSIG?  It's
      not a big deal, but some architectures have different values for _NSIG
      and SIGRTMAX.
      58e1dd1e
    • Andrew Morton's avatar
      [PATCH] NCR5380 timeout fix · 32ca1b05
      Andrew Morton authored
      From: Wagner_Volanin <fadinha.mail@terra.com.br>
      
      I have an old Genius Colorpage-SP2 SCSI scanner.  It is shipped with a
      MS-PNR 8bit ISA non-pnp proprietary SCSI card from Microtek.
      
      Although its chipset is a NCR53c400a, it wouldn't work with the appropriate
      driver, always accusing timeout, whatever settings I passed to it.
      
      Today I messed a little with the NCR5380.c file in drivers/scsi which is
      included by the g_NCR5380 driver and I couldn't understand one thing:
      
      Why the function NCR5380_poll_politely() returned the value 'r' on success
      if this value should be '0' case everything went ok...
      
      So I changed "return r;" to "return 0;" and after that my scanner worked
      fine, and was easily detected by SANE, without a single error message.  :)
      
      I have not the time to delve into the problem further, but I wanted to
      report this.  I couldn't find any counter-effects caused by changing these
      return values.
      
      (Acked by Alan)
      32ca1b05
    • Andrew Morton's avatar
      [PATCH] hangcheck compile fix · ce7073a0
      Andrew Morton authored
      From: john stultz <johnstul@us.ibm.com>
      
      Since monotonic_clock() is not defined on every arch yet, this patch
      insures the hangcheck-timer module (currently the only user of
      monotonic-clock) is not built where it will not compile.
      
      I know, I know. Ideally monotonic_clock() would be implemented on all
      arches, but I've just not had the time.  If any of the non x86/x86-64
      folks feel bored, drop me a line.  It'd be a fairly easy project.
      ce7073a0
    • Andrew Morton's avatar
      [PATCH] Export new char dev functions · e9d25628
      Andrew Morton authored
      From: Jonathan Corbet <corbet@lwn.net>
      
      Nobody told me that the failure to export these (like their block
      counterparts) was anything but an oversight; modules will not be able to
      use larger device numbers without them.  So...this patch exports the new
      char device functions.
      e9d25628
    • Andrew Morton's avatar
      [PATCH] Fix typo in scripts/postmod.c · deb13f63
      Andrew Morton authored
      From: Kristian Hogsberg <krh@bitplanet.net>
      
      There's a small typo in scripts/postmod.c
      deb13f63
    • Andrew Morton's avatar
      [PATCH] Update Documentation/block/biodoc.txt · 47b33392
      Andrew Morton authored
      From: Nick Piggin <piggin@cyberone.com.au>
      
      This brings biodoc.txt a bit more up to date with recent elevator changes.
      47b33392
    • Andrew Morton's avatar
      [PATCH] access_ok is likely · 2c2f8449
      Andrew Morton authored
      From Manfred
      
      While trying to figure out why sysv msg is around 30% slower than pipes for
      data transfers I noticed that gcc's autodetection (3.2.2) guesses the
      "if(access_ok())" tests in uaccess.h wrong and puts the error memset into the
      direct path and the copy out of line.
      
      So tell the compiler that access_ok() is likely to be true.
      2c2f8449
    • Andrew Morton's avatar
      [PATCH] remove /proc/config_build_info · 98badc08
      Andrew Morton authored
      From: Zwane Mwaikambo <zwane@linuxpower.ca>
      
      The same info is already available in /proc/version.
      98badc08
    • Andrew Morton's avatar
      [PATCH] floppy cleanup timers/resources on unload · b83bae67
      Andrew Morton authored
      From: Zwane Mwaikambo <zwane@linuxpower.ca>
      
      The floppy driver currently can leave pending timers after unloading
      itself.
      
      This bug has a corresponding bugzilla entry at;
      
      http://bugme.osdl.org/show_bug.cgi?id=1061
      b83bae67
    • Andrew Morton's avatar
      [PATCH] wanXL serial card driver · 614fc75e
      Andrew Morton authored
      From: Krzysztof Halasa <khc@pm.waw.pl>
      
      This is a driver for SBE Inc.  wanXL 4-port sync serial card, second
      version.
      614fc75e
    • Andrew Morton's avatar
      [PATCH] Summit sub-arch: Make logical IDs independent of BIOS numbering scheme · 33479170
      Andrew Morton authored
      From: James Cleverdon <jamesclv@us.ibm.com>
      
      In forthcoming IBM x445 systems, the physical APIC ID will not follow the
      simple rule laid out by Intel and encoded into xapic_phys_to_log_apicid.
      (The BIOS code that sets IDs doesn't work right above 16 CPUs if HT is turned 
      on, so for > 16-way the BIOS will disable HT and repack the physical CPUs
      into APIC clusters.)
      
      Anyway, it's a good idea to make the APIC code more independent of any
      particular BIOS numbering scheme.  This patch allocates logical IDs based on
      how many CPUs have already been onlined in a particular APIC cluster.
      33479170
    • Andrew Morton's avatar
      [PATCH] ens1370 PCI driver naming fix · c5d9f06f
      Andrew Morton authored
      From: Patrick Mochel <mochel@osdl.org>
      
      Two drivers are #including the same .c file.  Use them both and we get a
      sysfs naming clash.
      c5d9f06f
    • Andrew Morton's avatar
      [PATCH] fix incorrect argv[0] for init · fe713e4b
      Andrew Morton authored
      From: Erik Andersen <andersen@codepoet.org>
      
      When someone specifies "init=" to select an alternative binary to run
      instead of /sbin/init, argv[0] is not set correctly.  This is a problem for
      programs such as busybox that multiplex applications based on the value of
      argv[0].  For example, even if you specify init=/bin/sh" on the kernel
      command line, busybox will still receive "/sbin/init" as argv[0] and will
      therefore run init rather than /bin/sh...
      fe713e4b
    • Andrew Morton's avatar
      [PATCH] file locking memory leak · f5aaaa3e
      Andrew Morton authored
      From: Matthew Wilcox <willy@debian.org>
      
      This patch fixes a memory leak in the file locking code.  Each attempt to
      unlock a file would result in the leak of a file lock.  Many thanks to
      Martin Josefsson for providing the testcase which enabled me to figure out
      the problem.
      f5aaaa3e
    • Andrew Morton's avatar
      [PATCH] istallion: use schedule_work · a8424285
      Andrew Morton authored
      From: "Krishnakumar. R" <krishnakumar@naturesoft.net>
      
      A missing schedule_task -> schedule_work conversion.
      a8424285
    • Andrew Morton's avatar
      [PATCH] remove duplicate SOUND_RME96XX option · f8c4c726
      Andrew Morton authored
      From: Adrian Bunk <bunk@fs.tum.de>
      
      sound/oss/Kconfig in 2.6.0-test5 includes two SOUND_RME96XX entries.
      f8c4c726
    • Andrew Morton's avatar
      [PATCH] reiserfs: add checks from 2.4 into 2.5 · f4f81223
      Andrew Morton authored
      From: Oleg Drokin <green@namesys.com>
      
      This patch adds more consistency checks to reiserfs (check that transaction
      is not bigger than journal, check that we reply blocks not beyond fs and
      check that fs fits the block device).  Similar patch was included into 2.4
      some time ago.
      f4f81223
    • Andrew Morton's avatar
      [PATCH] misc fixes · 853fee92
      Andrew Morton authored
      - Remove dead declaration from elevator.h (Nick Piggin)
      
      - Fix the scheduler selection boot-time message.  "Using anticipatory
        scheduling io scheduler" is not grammatical.
      
      - Remove last use of __SMP__ (Randy Dunlap)
      853fee92
    • Andrew Morton's avatar
      [PATCH] allow x86 NUMA architecture detection to fail · 678937f0
      Andrew Morton authored
      From: Dave Hansen <haveblue@us.ibm.com>
      
      As described in this bug: http://bugme.osdl.org/show_bug.cgi?id=653 , if
      you enable Summit support and NUMA Discontigmem support but boot on a
      non-Summit box, the kernel will fail to boot.  The problem is that the
      Summit code can not correctly get the NUMA memory configuration of a
      flat box.  The code to do that is in get_memcfg_numa_flat(), but it
      never gets called.
      
      This patch implements a fallback to the generic NUMA code in
      get_memcfg_numa_flat() if the Summit detection fails.  The patch also
      adds the necessary bits to the Summit code so that it *knows* when it
      fails.
      678937f0
    • Andrew Morton's avatar
      [PATCH] any_online_cpu fix · 0774b4db
      Andrew Morton authored
      From: William Lee Irwin III <wli@holomorphy.com>
      
      any_online_cpu() is required to and with cpu_online_map before
      attempting to find an online cpu somewhere in the map; this patch adds
      that logic to the implementation(s) of any_online_cpu().
      0774b4db
    • Andrew Morton's avatar
      [PATCH] mwave char/Kconfig fix · bce22298
      Andrew Morton authored
      From: Angus Sawyer <angus.sawyer@dsl.pipex.com>
      
      The mwave driver requires [un]register_char from 8250.c
      Make sure 8250.c gets compilied.
      bce22298
    • Andrew Morton's avatar
      [PATCH] AGP warning fix · fdf63fc4
      Andrew Morton authored
      agp_setup() is unreferenced if it's a module.
      fdf63fc4
    • Andrew Morton's avatar
      [PATCH] Remove Documentation/smp.tex · 227ed0b8
      Andrew Morton authored
      Hopelessly out of date
      227ed0b8
    • Andrew Morton's avatar
      [PATCH] Move slab objects to the end of the real allocation · e0c22e53
      Andrew Morton authored
      From: Manfred Spraul <manfred@colorfullife.com>
      
      The real memory allocation is usually larger than the actual object size:
      either due to L1 cache line padding, or due to page padding with
      CONFIG_DEBUG_PAGEALLOC.  Right now objects are placed to the beginning of
      the real allocation, but to trigger bugs it's better to move objects to the
      end of the real allocation: that way accesses behind the end of the
      allocation have a larger chance of hitting the (unmapped) next page.  The
      attached patch moves the objects to align them with the end of the real
      allocation.
      
      Actually it contains 4 seperate changes:
      
      - Do not page-pad allocations that are <= SMP_CACHE_LINE_SIZE.  This
        crashes.  Right now the limit is hardcoded to 128 bytes, but sooner or
        later an arch will appear with 256 byte cache lines.
      
      - cleanup: redzone bytes are not accessed with inline helper functions,
        instead of magic offsets scattered throughout slab.c
      
      - main change: move objects to the end of the allocation - trivial after
        the cleanup.
      
      - Print old redzone value if a redzone mismatch happens: This makes it
        simpler to figure out what happened [single bit error, wrong redzone
        code, overwritten]
      e0c22e53
    • Andrew Morton's avatar
      [PATCH] might_sleep diagnostics · d6dbfa23
      Andrew Morton authored
      might_sleep() can be triggered by either local interrupts being disabled or
      by elevated preempt count.  Disambiguate them.
      d6dbfa23
    • Andrew Morton's avatar
      [PATCH] CPU scheduler interactivity changes · 2cf13d58
      Andrew Morton authored
      From: Con Kolivas <kernel@kolivas.org>
      
      Interactivity scheduler tweaks on top of Ingo's A3 interactivity patch.
      
      Interactive credit added to task struct to find truly interactive tasks and
      treat them differently.
      
      Extra #defines included as helpers for conversion to/from nanosecond timing,
      to work out an average timeslice for nice 0 tasks, and the effective dynamic
      priority bonuses that will be given to tasks.
      
      MAX_SLEEP_AVG modified to change dynamic priority by one for a nice 0 task
      sleeping or running for one full timeslice.
      
      CREDIT_LIMIT is the number of times a task earns sleep_avg over MAX_SLEEP_AVG
      before it is considered HIGH_CREDIT (truly interactive); and -CREDIT_LIMIT is
      LOW_CREDIT
      
      TIMESLICE GRANULARITY is modified to be more frequent for more
      interactivetasks (10 ms for top 2 dynamic priorities and then halving each
      priority belowthat) and less frequent per extra cpu.
      
      JUST_INTERACTIVE_SLEEP logic created to be a sleep_avg consistent with giving
      a task enough dynamic priority to remain on the active array.
      
      Task preemption of equal priority tasks is dropped as requeuing with
      TIMESLICE_GRANULARITY makes this unecessary.
      
      Dynamic priority bonus simplified.
      
      User tasks that sleep a long time and not waking from uninterruptible sleep
      are sought and categorised as idle. Their sleep avg is limited in it's rise to
      prevent them becoming high priority and suddenly turning into cpu hogs.
      
      Bonus for sleeping is proportionately higher the lower the dynamic priority of
      a task is; this allows for very rapid escalation to interactive status.
      
      Tasks that are LOW_CREDIT are limited in rise per sleep to one priority level.
      
      Non HIGH_CREDIT tasks waking from uninterruptible sleep are sought to detect
      cpu hogs waiting on I/O and their sleep_avg rise is limited to just
      interactive state to prevent cpu bound tasks from becoming interactive during
      I/O wait.
      
      Tasks that earn sleep_avg over MAX_SLEEP_AVG get interactive credits.
      
      On runqueue bonus is not given to non HIGH_CREDIT tasks waking from
      uninterruptible sleep.
      
      Forked tasks and their parents get sleep_avg limited to the minimum necessary
      to maintain their effective dynamic priority thus preventing repeated forking
      from being a way to get highly interactive, but not penalise them noticably
      otherwise.
      
      CAN_MIGRATE_TASK cleaned up and modified to work with nanosecond timestamps.
      
      Reverted Ingo's A3 Starvation limit change - it was making interactive tasks
      suffer more under increasing load. If a cpu is grossly overloaded and
      everyone is going to starve it may as well run interactive tasks
      preferentially.
      
      Task requeuing is limited to interactive tasks only (cpu bound tasks dont need
      low latency and derive benefit from longer timeslices), and they must have at
      least TIMESLICE_GRANULARITY remaining.
      
      HIGH_CREDIT tasks get penalised less sleep_avg the more interactive they are
      thus keeping them interactive for bursts but if they become sustained cpu hogs
      they will slide increasingly rapidly down the dynamic priority scale.
      
      Tasks that run out of sleep_avg, are still using up cpu time and are not high
      or low credit yet get penalised interactive credits to determine LOW_CREDIT
      tasks (cpu bound ones).
      2cf13d58
    • Andrew Morton's avatar
      [PATCH] CPU scheduler balancing fix · 875ee1e1
      Andrew Morton authored
      From: Nick Piggin <piggin@cyberone.com.au>
      
      The patch changes the imbalance required before a balance to 25% from 50% -
      as the comments intend.  It also changes a case where the balancing
      wouldn't be done if the imbalance was >= 25% but only 1 task difference.
      
      The downside of the second change is that one task may bounce from one cpu
      to another for some loads.  This will only bounce once every 200ms, so it
      shouldn't be a big problem.
      
      (Benchmarking results are basically a wash - SDET is increased maybe 0.5%)
      875ee1e1
    • Andrew Morton's avatar
      [PATCH] sched_clock() for ppc, ppc64, x86_64 and sparc64 · 2b7e8ff7
      Andrew Morton authored
      Ingo's CPU scheduler update (in -mm kernels) needs a new sched_clock()
      function which returns nanoseconds.
      
      The patch provides implementations for ppc, ppc64, x86_64 and sparc64.
      
      The x86_64 version could have overflow issues, the calculation is done in
      32bits only with an multiply.  But I hope it's good enough for the scheduler
      
      The ppc64 version needs scaling: it's only accurate for 1GHz CPUs.
      2b7e8ff7
    • Andrew Morton's avatar
      [PATCH] scheduler infrastructure · f221af36
      Andrew Morton authored
      From: Ingo Molnar <mingo@elte.hu>
      
      the attached scheduler patch (against test2-mm2) adds the scheduling
      infrastructure items discussed on lkml. I got good feedback - and while i
      dont expect it to solve all problems, it does solve a number of bad ones:
      
       - test_starve.c code from David Mosberger
      
       - thud.c making the system unusuable due to unfairness
      
       - fair/accurate sleep average based on a finegrained clock
      
       - audio skipping way too easily
      
      other changes in sched-test2-mm2-A3:
      
       - ia64 sched_clock() code, from David Mosberger.
      
       - migration thread startup without relying on implicit scheduling
         behavior. While the current 2.6 code is correct (due to the cpu-up code
         adding CPUs one by one), but it's also fragile - and this code cannot
         be carried over into the 2.4 backports. So adding this method would
         clean up the startup and would make it easier to have 2.4 backports.
      
      and here's the original changelog for the scheduler changes:
      
       - cycle accuracy (nanosec resolution) timekeeping within the scheduler.
         This fixes a number of audio artifacts (skipping) i've reproduced. I
         dont think we can get away without going cycle accuracy - reading the
         cycle counter adds some overhead, but it's acceptable. The first
         nanosec-accuracy patch was done by Mike Galbraith - this patch is
         different but similar in nature. I went further in also changing the
         sleep_avg to be of nanosec resolution.
      
       - more finegrained timeslices: there's now a timeslice 'sub unit' of 50
         usecs (TIMESLICE_GRANULARITY) - CPU hogs on the same priority level
         will roundrobin with this unit. This change is intended to make gaming
         latencies shorter.
      
       - include scheduling latency in sleep bonus calculation. This change
         extends the sleep-average calculation to the period of time a task
         spends on the runqueue but doesnt get scheduled yet, right after
         wakeup. Note that tasks that were preempted (ie. not woken up) and are
         still on the runqueue do not get this benefit. This change closes one
         of the last hole in the dynamic priority estimation, it should result
         in interactive tasks getting more priority under heavy load. This
         change also fixes the test-starve.c testcase from David Mosberger.
      
      
      The TSC-based scheduler clock is disabled on ia32 NUMA platforms.  (ie. 
      platforms that have unsynched TSC for sure.) Those platforms should provide
      the proper code to rely on the TSC in a global way.  (no such infrastructure
      exists at the moment - the monotonic TSC-based clock doesnt deal with TSC
      offsets either, as far as i can tell.)
      f221af36
    • Andrew Morton's avatar
      [PATCH] NLS: remove emacs metadata · 1dffaaf7
      Andrew Morton authored
      From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
      
      This elisp was obsolete on recently emacs's cc-mode. And this should
      be personally set.
      1dffaaf7
    • Andrew Morton's avatar
      [PATCH] NLS: Remove the nls modules for only alias · 644f9658
      Andrew Morton authored
      From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
      
      This does the following,
      
      1) This removes the nls modules for only alias. For backward
         compatible, this adds ->alias, and ->alias provides alias of charset.
      
      2) For autoloading the module by the alias, use MODULE_ALIAS mechanism.
      
      3) From changelog of module-init-tools, looks like MODULE_ALIAS needs
         module-init-tools 0.9.10 or later. So change the "Documentation/Changes".
      644f9658
    • Andrew Morton's avatar
      [PATCH] mtrr warning fix w/o proc_fs · 03329f13
      Andrew Morton authored
      From: Stephen Hemminger <shemminger@osdl.org>
      
      Get rid of warnings (and dead code) if MTRR is compiled without /proc
      03329f13
    • Andrew Morton's avatar
      [PATCH] Overflow check for i386 assign_irq_vector · f9e416d3
      Andrew Morton authored
      From: James Cleverdon <jamesclv@us.ibm.com>
      
      Some very large systems overflow the array and corrupt memory.  A BUG_ON will 
      at least flag the problem until dynamic irq_vector allocation is added.
      f9e416d3
    • Andrew Morton's avatar
      [PATCH] reiserfs: large file 32/64-bit truncation fix · 9edad7f8
      Andrew Morton authored
      From: Oleg Drokin <green@namesys.com>
      
      Fix trucation-induced large file corruption in reiserfs.
      9edad7f8
    • Andrew Morton's avatar
      [PATCH] Fix setpgid and threads · feaecce4
      Andrew Morton authored
      From: Jeremy Fitzhardinge <jeremy@goop.org>
      
      I'm resending my patch to fix this problem.  To recap: every task_struct
      has its own copy of the thread group's pgrp.  Only the thread group
      leader is allowed to change the tgrp's pgrp, but it only updates its own
      copy of pgrp, while all the other threads in the tgrp use the old value
      they inherited on creation.
      
      This patch simply updates all the other thread's pgrp when the tgrp
      leader changes pgrp.  Ulrich has already expressed reservations about
      this patch since it is (1) incomplete (it doesn't cover the case of
      other ids which have similar problems), (2) racy (it doesn't synchronize
      with other threads looking at the task pgrp, so they could see an
      inconsistent view) and (3) slow (it takes linear time with respect to
      the number of threads in the tgrp).
      
      My reaction is that (1) it fixes the actual bug I'm encountering in a
      real program.  (2) doesn't really matter for pgrp, since it is mostly an
      issue with respect to the terminal job-control code (which is even more
      broken without this patch.  Regarding (3), I think there are very few
      programs which have a large number of threads which change process group
      id on a regular basis (a heavily multi-threaded job-control shell?).
      
      Ulrich also said he has a (proposed?) much better fix, which I've been
      looking forward to.  I'm submitting this patch as a stop-gap fix for a
      real bug, and perhaps to prompt the improved patch.
      
      An alternative fix, at least for pgrp, is to change all references to
      ->pgrp to group_leader->pgrp.  This may be sufficient on its own, but it
      would be a reasonably intrusive patch (I count 95 instances in 32 files
      in the 2.6.0-test3-mm3 tree).
      feaecce4
    • Andrew Morton's avatar
      [PATCH] real-time enhanced page allocator and throttling · 55b50278
      Andrew Morton authored
      From: Robert Love <rml@tech9.net>
      
      - Let real-time tasks dip further into the reserves than usual in
        __alloc_pages().  There are a lot of ways to special case this.  This
        patch just cuts z->pages_low in half, before doing the incremental min
        thing, for real-time tasks.  I do not do anything in the low memory slow
        path.  We can be a _lot_ more aggressive if we want.  Right now, we just
        give real-time tasks a little help.
      
      - Never ever call balance_dirty_pages() on a real-time task.  Where and
        how exactly we handle this is up for debate.  We could, for example,
        special case real-time tasks inside balance_dirty_pages().  This would
        allow us to perform some of the work (say, waking up pdflush) but not
        other work (say, the active throttling).  As it stands now, we do the
        per-processor accounting in balance_dirty_pages_ratelimited() but we
        never call balance_dirty_pages().  Lots of approaches work.  What we want
        to do is never engage the real-time task in forced writeback.
      55b50278
    • Andrew Morton's avatar
      [PATCH] ECC support · 5fc4d839
      Andrew Morton authored
      From: "Nakajima, Jun" <jun.nakajima@intel.com>
      
      Split the increasingly messy compiler.h file into per-compiler files and also
      add support for non-gcc compilers.  
      
      With the current implementation:
      
        include/linux/compiler.h defines the compiler-dependent abstractions
        which can be overwritten by per-compiler definitions.
      
        include/linux/compiler-gcc.h contains the common definitions for all gcc
        versions.
      
        include/linux/compiler-gcc[2,3,+].h contains gcc major version specific
        definitions.
      
        include/linux/compiler-intel.h contains intel compiler specific
        definitions."
      5fc4d839