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  1. 26 May, 2009 4 commits
    • Mathieu Desnoyers's avatar
      [CPUFREQ] fix timer teardown in conservative governor · b253d2b2
      Mathieu Desnoyers authored 
      * Rafael J. Wysocki (rjw@sisk.pl) wrote:
> This message has been generated automatically as a part of a report
> of regressions introduced between 2.6.28 and 2.6.29.
>
> The following bug entry is on the current list of known regressions
> introduced between 2.6.28 and 2.6.29.  Please verify if it still should
> be listed and let me know (either way).
>
>
> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13186
> Subject		: cpufreq timer teardown problem
> Submitter	: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> Date		: 2009-04-23 14:00 (24 days old)
> References	: http://marc.info/?l=linux-kernel&m=124049523515036&w=4
> Handled-By	: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> Patch		: http://patchwork.kernel.org/patch/19754/
> 		  http://patchwork.kernel.org/patch/19753/
>

(re-send with updated changelog)

cpufreq fix timer teardown in conservative governor

The problem is that dbs_timer_exit() uses cancel_delayed_work() when it should
use cancel_delayed_work_sync(). cancel_delayed_work() does not wait for the
workqueue handler to exit.

The ondemand governor does not seem to be affected because the
"if (!dbs_info->enable)" check at the beginning of the workqueue handler returns
immediately without rescheduling the work. The conservative governor in
2.6.30-rc has the same check as the ondemand governor, which makes things
usually run smoothly. However, if the governor is quickly stopped and then
started, this could lead to the following race :

dbs_enable could be reenabled and multiple do_dbs_timer handlers would run.
This is why a synchronized teardown is required.

Depends on patch
cpufreq: remove rwsem lock from CPUFREQ_GOV_STOP call

The following patch applies to 2.6.30-rc2. Stable kernels have a similar
issue which should also be fixed, but the code changed between 2.6.29
and 2.6.30, so this patch only applies to 2.6.30-rc.
Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: gregkh@suse.de
CC: stable@kernel.org
CC: cpufreq@vger.kernel.org
CC: Ingo Molnar <mingo@elte.hu>
CC: rjw@sisk.pl
CC: Ben Slusky <sluskyb@paranoiacs.org>
Signed-off-by: default avatarDave Jones <davej@redhat.com>
      b253d2b2
    • Mathieu Desnoyers's avatar
      [CPUFREQ] remove rwsem lock from CPUFREQ_GOV_STOP call · 42a06f21
      Mathieu Desnoyers authored 
      * Rafael J. Wysocki (rjw@sisk.pl) wrote:
> This message has been generated automatically as a part of a report
> of regressions introduced between 2.6.28 and 2.6.29.
>
> The following bug entry is on the current list of known regressions
> introduced between 2.6.28 and 2.6.29.  Please verify if it still should
> be listed and let me know (either way).
>
>
> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13186
> Subject		: cpufreq timer teardown problem
> Submitter	: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> Date		: 2009-04-23 14:00 (24 days old)
> References	: http://marc.info/?l=linux-kernel&m=124049523515036&w=4
> Handled-By	: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> Patch		: http://patchwork.kernel.org/patch/19754/
> 		  http://patchwork.kernel.org/patch/19753/

The patches linked above depend on the following patch to remove
circular locking dependency :

cpufreq: remove rwsem lock from CPUFREQ_GOV_STOP call

(the following issue was faced when using cancel_delayed_work_sync() in the
timer teardown (which fixes a race).

* KOSAKI Motohiro (kosaki.motohiro@jp.fujitsu.com) wrote:
> Hi
>
> my box output following warnings.
> it seems regression by commit 7ccc7608b836e58fbacf65ee4f8eefa288e86fac.
>
> A: work -> do_dbs_timer()  -> cpu_policy_rwsem
> B: store() -> cpu_policy_rwsem -> cpufreq_governor_dbs() -> work
>
>

Hrm, I think it must be due to my attempt to fix the timer teardown race
in ondemand governor mixed with new locking behavior in 2.6.30-rc.

The rwlock seems to be taken around the whole call to
cpufreq_governor_dbs(), when it should be only taken around accesses to
the locked data, and especially *not* around the call to
dbs_timer_exit().

Reverting my fix attempt would put the teardown race back in place
(replacing the cancel_delayed_work_sync by cancel_delayed_work).
Instead, a proper fix would imply modifying this critical section :

cpufreq.c: __cpufreq_remove_dev()
...
        if (cpufreq_driver->target)
                __cpufreq_governor(data, CPUFREQ_GOV_STOP);

        unlock_policy_rwsem_write(cpu);

To make sure the __cpufreq_governor() callback is not called with rwsem
held. This would allow execution of cancel_delayed_work_sync() without
being nested within the rwsem.

Applies on top of the 2.6.30-rc5 tree.

Required to remove circular dep in teardown of both conservative and
ondemande governors so they can use cancel_delayed_work_sync().
CPUFREQ_GOV_STOP does not modify the policy, therefore this locking seemed
unneeded.
Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Greg KH <greg@kroah.com>
CC: Ingo Molnar <mingo@elte.hu>
CC: "Rafael J. Wysocki" <rjw@sisk.pl>
CC: Ben Slusky <sluskyb@paranoiacs.org>
CC: Chris Wright <chrisw@sous-sol.org>
CC: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDave Jones <davej@redhat.com>
      42a06f21
    • Dave Jones's avatar
      [CPUFREQ] powernow-k7 build fix when ACPI=n · d38e73e8
      Dave Jones authored 
      arch/x86/kernel/cpu/cpufreq/powernow-k7.c:172: warning: 'invalidate_entry' defined but not used
Reported-by: default avatarToralf Förster <toralf.foerster@gmx.de>
Signed-off-by: default avatarDave Jones <davej@redhat.com>
      d38e73e8
    • Jarod Wilson's avatar
      [CPUFREQ] add atom family to p4-clockmod · 43195037
      Jarod Wilson authored 
      Some atom procs don't do freq scaling (such as the atom 330 on my own
littlefalls2 board). By adding the atom family here, we at least get
the benefit of passive cooling in a thermal emergency. Not sure how
to see that its actually helping any, but the driver does bind and
claim its functioning on my atom 330.
Signed-off-by: default avatarJarod Wilson <jarod@redhat.com>
Signed-off-by: default avatarDave Jones <davej@redhat.com>
      43195037
  3. 25 May, 2009 6 commits
  5. 24 May, 2009 3 commits
  7. 23 May, 2009 5 commits
    • Linus Torvalds's avatar
      Linux 2.6.30-rc7 · 59a3759d
      Linus Torvalds authored
      59a3759d
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6 · 4a5dacec
      Linus Torvalds authored 
      * git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6:
  [SCSI] mpt2sas: fix driver version inconsistency
  [SCSI] 3w-xxxx: scsi_dma_unmap fix
  [SCSI] 3w-9xxx: scsi_dma_unmap fix
  [SCSI] ses: fix problems caused by empty SES provided name
  [SCSI] fc-transport: Close state transition-window during rport deletion.
  [SCSI] initialize max_target_blocked in scsi_alloc_target
  [SCSI] fnic: Add new Cisco PCI-Express FCoE HBA
      4a5dacec
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6 · 3eb9c8be
      Linus Torvalds authored 
      * git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6:
  [CIFS] Avoid open on possible directories since Samba now rejects them
      3eb9c8be
    • Steve French's avatar
      [CIFS] Avoid open on possible directories since Samba now rejects them · 8db14ca1
      Steve French authored 
      Small change (mostly formatting) to limit lookup based open calls to
file create only.

After discussion yesteday on samba-technical about the posix lookup
regression,  and looking at a problem with cifs posix open to one
particular Samba version, Jeff and JRA realized that Samba server's
behavior changed in this area (posix open behavior on files vs.
directories).   To make this behavior consistent, JRA just made a
fix to Samba server to alter how it handles open of directories (now
returning the equivalent of EISDIR instead of success). Since we don't
know at lookup time whether the inode is a directory or file (and
thus whether posix open will succeed with most current Samba server),
this change avoids the posix open code on lookup open (just issues
posix open on creates).    This gets the semantic benefits we want
(atomicity, posix byte range locks, improved write semantics on newly
created files) and file create still is fast, and we avoid the problem
that Jeff noticed yesterday with "openat" (and some open directory
calls) of non-cached directories to one version of Samba server, and
will work with future Samba versions (which include the fix jra just
pushed into Samba server).  I confirmed this approach with jra
yesterday and with Shirish today.

Posix open is only called (at lookup time) for file create now.
For opens (rather than creates), because we do not know if it
is a file or directory yet, and current Samba no longer allows
us to do posix open on dirs, we could end up wasting an open call
on what turns out to be a dir. For file opens, we wait to call posix
open till cifs_open.  It could be added here (lookup) in the future
but the performance tradeoff of the extra network request when EISDIR
or EACCES is returned would have to be weighed against the 50%
reduction in network traffic in the other paths.
Reviewed-by: default avatarShirish Pargaonkar <shirishp@us.ibm.com>
Tested-by: default avatarJeff Layton <jlayton@redhat.com>
CC: Jeremy Allison <jra@samba.org>
Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
      8db14ca1
    • Breno Leitao's avatar
      icom: fix rmmod crash · 95caa0a9
      Breno Leitao authored 
      Actually the icom driver is crashing when is being removed because
the driver is kfreeing the adapter structure before calling
pci_release_regions(), which result in the following error:

  Unable to handle kernel paging request for data at address 0x6b6b6b6b6b6b6d33
  Faulting instruction address: 0xc000000000246b80
  Oops: Kernel access of bad area, sig: 11 [#1]
  ....
  [c000000012d436a0] [c0000000001002d0] .kfree+0x120/0x34c (unreliable)
  [c000000012d43730] [c000000000246d60] .pci_release_selected_regions+0x3c/0x68
  [c000000012d437c0] [d000000002d54700] .icom_kref_release+0xf4/0x118 [icom]
  [c000000012d43850] [c000000000232e50] .kref_put+0x74/0x94
  [c000000012d438d0] [d000000002d56c58] .icom_remove+0x40/0xa4 [icom]
  [c000000012d43960] [c000000000249e48] .pci_device_remove+0x50/0x90
  [c000000012d439e0] [c0000000002d68d8] .__device_release_driver+0x94/0xd4
  [c000000012d43a70] [c0000000002d7104] .driver_detach+0xf8/0x12c
  [c000000012d43b00] [c0000000002d549c] .bus_remove_driver+0xbc/0x11c
  [c000000012d43b90] [c0000000002d71dc] .driver_unregister+0x60/0x80
  [c000000012d43c20] [c00000000024a07c] .pci_unregister_driver+0x44/0xe8
  [c000000012d43cb0] [d000000002d56bf4] .icom_exit+0x1c/0x40 [icom]
  [c000000012d43d30] [c000000000095fa8] .SyS_delete_module+0x214/0x2a8
  [c000000012d43e30] [c00000000000852c] syscall_exit+0x0/0x40
Signed-off-by: default avatarBreno Leitao <leitao@linux.vnet.ibm.com>
Cc: stable@kernel.org
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      95caa0a9
  9. 22 May, 2009 22 commits
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