For some clocks, the old Ironlake DPLL calculator wold give m/n/p
combinations that didn't match the spreadsheet of what HW validation
tests. Instead, use the G4X DPLL calculator, which does a better job
at it.
So we use the intel_g4x_find_best_pll to calculate the DPLL for CRT/HDMI/LVDS
on ironlake. At the same time to consider the dpll setting for display port, we
add the display port DPLL limit on ironlake, which will directly use the
function of intel_find_pll_ironlake_dp to get the corresponding dpll setting.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Select the correct BPC for LVDS on Ironlake. If it is 18-bit LVDS panel,
the BPC will be 6. When it is 24-bit LVDS panel, the BPC will 8.
At the same time the BPC will be 8 when the output device is CRT/HDMI/DP.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Make the BPC in FDI rx/transcoder be consistent with that in pipeconf on Ironlake.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Enable/disable the dithering for LVDS based on VBT setting. On the 965/g4x
platform the dithering flag is defined in LVDS register. And on the ironlake
the dithering flag is defined in pipeconf register.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
As pinning (allocating and binding GTT memory) does not actually invoke
GPU commands, it is safe, and indeed is attempted, during resumption
from suspension:
[drm:intel_init_clock_gating] *ERROR* failed to pin power context: -16
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reported-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: stable@kernel.org
Signed-off-by: Eric Anholt <eric@anholt.net>
Hugh found an error path where we were attempting to unref a bo without
holding the struct mutex:
[drm:intel_init_clock_gating] *ERROR* failed to pin power context: -16
------------[ cut here ]------------
WARNING: at drivers/gpu/drm/drm_gem.c:438 drm_gem_object_free+0x20/0x5e()
Hardware name: ESPRIMO Mobile V5505
Modules linked in: snd_pcm_oss snd_mixer_oss snd_seq snd_seq_device
Pid: 3793, comm: s2ram Not tainted 2.6.33-rc2 #4
Call Trace:
[<7815298e>] warn_slowpath_common+0x59/0x6b
[<781529b3>] warn_slowpath_null+0x13/0x18
[<78317c1a>] ? drm_gem_object_free+0x20/0x5e
[<78317c1a>] drm_gem_object_free+0x20/0x5e
[<78317bfa>] ? drm_gem_object_free+0x0/0x5e
[<7829df11>] kref_put+0x38/0x45
[<7833a5f0>] intel_init_clock_gating+0x232/0x271
[<78317bfa>] ? drm_gem_object_free+0x0/0x5e
[<7832c307>] i915_restore_state+0x21a/0x2b3
[<7832379d>] i915_resume+0x3c/0xbb
[<78174fe5>] ? trace_hardirqs_on_caller+0xfc/0x123
[<7831c756>] ? drm_class_resume+0x0/0x3e
[<7831c78d>] drm_class_resume+0x37/0x3e
[<78351e0a>] legacy_resume+0x1e/0x51
[<78351ece>] device_resume+0x91/0xab
[<7831c756>] ? drm_class_resume+0x0/0x3e
[<78352226>] dpm_resume+0x58/0x10f
[<783522fb>] dpm_resume_end+0x1e/0x2c
[<78180f80>] suspend_devices_and_enter+0x61/0x84
[<78180ff8>] enter_state+0x55/0x83
[<7818091c>] state_store+0x94/0xaa
[<7829d09e>] kobj_attr_store+0x1e/0x23
[<782098e0>] sysfs_write_file+0x66/0x99
[<781cd2f0>] vfs_write+0x8a/0x108
[<781cd408>] sys_write+0x3c/0x63
[<78125c10>] sysenter_do_call+0x12/0x36
---[ end trace a343537f29950fda ]---
It is in fact slightly more insiduous that first appears since we are
attempting to not just free the object without the lock, but are trying
to do the whole bo manipulation without holding the lock.
Reported-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
Signed-off-by: Eric Anholt <eric@anholt.net>
drivers/gpu/drm/i915/i915_dma.c: In function 'i915_driver_load':
drivers/gpu/drm/i915/i915_dma.c:1114: warning: 'll_base' may be used uninitialized in this function
Partly this is because gcc isn't smart enough. But `ll_base' does get used
uninitialised in the DRM_DEBUG() call.
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
The C99 specification states in section 6.11.5:
The placement of a storage-class specifier other than at the beginning
of the declaration specifiers in a declaration is an obsolescent
feature.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Eric Anholt <eric@anholt.net>
This code generally fails to adjust the render clock, and when it does,
it conflicts with some other register settings and can cause problems.
So remove this code altogether. I'm reworking it now to do the right
thing, but the only bit it will share is the VBT check for whether
reclocking is supported, so I'm leaving that bit.
Reverts most of 652c393a33 ("add dynamic
clock frequency control"), though for many the regressions showed up
in the later 181a5336d6 ("Fix render
reclock availability detection").
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
We restored RC6 twice on resume, even with modesetting off. Instead,
only restore it once and skip RC6 initialization entirely in non-KMS mode.
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Tested-by: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
This patch adds a new execbuf ioctl, execbuf2, for use by clients that
want to control fence register allocation more finely. The buffer
passed in to the new ioctl includes a new relocation type to indicate
whether a given object needs a fence register assigned for the command
buffer in question.
Compatibility with the existing execbuf ioctl is implemented in terms
of the new code, preserving the assumption that fence registers are
required for pre-965 rendering commands.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
[ickle: Remove pre-emptive clear_fence_reg()]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Kristian Høgsberg <krh@bitplanet.net>
[anholt: Removed dmesg spam]
Signed-off-by: Eric Anholt <eric@anholt.net>
Adds the device_enable function to the DaVinci Keyscan platform data
to setup the PINMUX configuration.
It also removes #ifdef from the DM365 EVM board in order to load it
properly as a module.
Signed-off-by: Miguel Aguilar <miguel.aguilar@ridgerun.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
All DaVinci platforms include a DSP or co-processor for
audio/video acceleration.
While creating memory for the DSP/co-processor, system
integrator can end up creating a hole in the memory map
of the sort:
<kernel memory> <hole (memory for DSP)> <kernel memory>
This sort of configuration needs ARCH_HAS_HOLES_MEMORYMODEL
enabled. See further details see this discussion on ARM
linux mailing list:
http://www.mail-archive.com/linux-omap@vger.kernel.org/msg15262.html
The patch is boot tested on OMAP-L138, DM6446 and DM355 EVMs
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
CC: Sriramakrishnan <srk@ti.com>
CC: Khasim Syed Mohammed <khasim@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
On da850, RTC alarm is a wakeup source from deep sleep.
Mark it as a wakeup source after the rtc platform device
is registered.
Without this patch, the rtc-omap driver suspends the RTC
during the suspend sequence and hence it cannot wakeup the
SoC.
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
There is nothing special to be done for interrupts
which can wakeup the device from sleep on CP-INTC,
but not having a set_wake implemented prevents use
of common drivers which expect this function to be
implemented for all wakeup interrupt sources.
This patch fixes the issue encountered when using the
omap-rtc driver on DA850. On DA850 the RTC alarm
interrupt is used to wake up the SoC from deep sleep
mode. Without this patch, the disable_irq_wake throws
an unbalanced wake disable warning while resuming
because the previous enable call fails for lack of
set_wake implementation.
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
The I2C adapter ID is actually depends on Board and may vary, Davinci
uses id=1, but in case of AM3517 id=3.
So modified respective davinci board files.
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
* 'for-linus' of git://git.open-osd.org/linux-open-osd:
exofs: simple_write_end does not mark_inode_dirty
exofs: fix pnfs_osd re-definitions in pre-pnfs trees
* master.kernel.org:/home/rmk/linux-2.6-arm: (22 commits)
ARM: 5865/1: nuc900 ethernet driver needs mii
ARM: 5864/1: Implement arch_reset() in NUC900
ARM: 5863/1: fix bugs of clock source of NUC900
ARM: 5858/1: Remove unused vma_vm_flags macro from v7wbi_flush_user_tlb_range
imx/mx3: depend on USB_ULPI for otg_ulpi_create
ARM: MX3: make CPU revision number detection work on all boards
mx25: pdk: add platform code for FEC support
mx25: add support for FEC on i.MX25
mx25: s/NO_PAD_CTL/NO_PAD_CTRL/
mx31moboard: fix usbh device names
mx3: add support for the mt9v022 camera sensor to pcm037 platform
mx27: mxt_td60: Remove not used UART pins
[ARM] pxa/poodle: fix incorrect 'gpio_card_detect' of MMC
[ARM] pxa/zylonite: simplify reduntant gpio settings on mmc slot
[ARM] pxa/ttc_dkb: remove duplicate macro definition
[ARM] pxa/zeus: provide power-source information when APM is enabled
[ARM] pxa/zeus: relax memory timings on Zeus ethernet ports
[ARM] pxa/zeus: make internal zeus_get_pcb_info static
[ARM] pxa/littleton: select CPU_PXA300 and CPU_PXA310
[ARM] pxa/littleton: add UART3 GPIO config
...
Commit 35dead4 "modules: don't export section names of empty sections
via sysfs" changed the set of sections that have attributes, but did
not change the iteration over these attributes in add_notes_attrs().
This can lead to add_notes_attrs() creating attributes with the wrong
names or with null name pointers.
Introduce a sect_empty() function and use it in both add_sect_attrs()
and add_notes_attrs().
Reported-by: Martin Michlmayr <tbm@cyrius.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Tested-by: Martin Michlmayr <tbm@cyrius.com>
Cc: stable@kernel.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Look up primary dac adj values from the table if
there is no bios or bios dac table to reference.
The lookup table may need to be adjusted for certain
families.
Should fix kernel bug 14945.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
if necessary for combios
Some early combios radeon cards don't have a connector
table or dac table in the bios, if they do not, fallback
to the default tables.
Should fix kernel bug 14963.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
sparc64: Fix Niagara2 perf event handling.
sparc64: Fix NMI programming when perf events are active.
bbc_envctrl: Clean up properly if kthread_run() fails.
This reverts commit ae1b22f6e4.
As Linus said in 982d007a6ee: "There was something really messy about
cmpxchg8b and clone CPU's, so if you enable it on other CPUs later, do it
carefully."
This breaks lguest for those configs, but we can fix that by emulating
if we have to.
Fixes: http://bugzilla.kernel.org/show_bug.cgi?id=14884
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-2.6.33' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound-2.6:
ASoC: fixup oops in generic AC97 codec glue
ASoC: fix params_rate() macro use in several codecs
ASoC: fsi-ak4642: Remove ak4642_add_i2c_device
Callers of copy_from_user() expect it to return the number of bytes
it could not copy. In no case it is supposed to return -EFAULT.
In case of a detected buffer overflow just return the requested
length. In addition one could think of a memset that would clear
the size of the target object.
[ hpa: code is not in .32 so not needed for -stable ]
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20100105131911.GC5480@osiris.boeblingen.de.ibm.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
nuc900 ethernet driver uses mii_xx_xx serials api, so mii module should be selected.
Signed-off-by: lijie <eltshanli@gmail.com>
Acked-by: Wan ZongShun <mcuos.com@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Implement arch_reset(), reboot from shell become possible.
Signed-off-by: lijie <eltshanli@gmail.com>
Acked-by: Wan ZongShun <mcuos.com@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch fix following bugs:
1. typo error, CLOCK_EVT_MODE_PERIODIC -> CLOCK_EVT_FEAT_PERIODIC
2. TCSR register of timer1 missed PRESCALE
3. timer1 should be enabled before register it to clock source.
Signed-off-by: lijie <eltshanli@gmail.com>
Acked-by: Wan ZongShun <mcuos.com@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
For chips like Niagara2 that have true overflow indications
in the %pcr (which we don't actually need and don't use)
the interrupt signal persists until the overflow bits are
cleared by an explicit %pcr write.
Signed-off-by: David S. Miller <davem@davemloft.net>
exofs uses simple_write_end() for it's .write_end handler. But
it is not enough because simple_write_end() does not call
mark_inode_dirty() when it extends i_size. So even if we do
call mark_inode_dirty at beginning of write out, with a very
long IO and a saturated system we might get the .write_inode()
called while still extend-writing to file and miss out on the last
i_size updates.
So override .write_end, call simple_write_end(), and afterwords if
i_size was changed call mark_inode_dirty().
It stands to logic that since simple_write_end() was the one extending
i_size it should also call mark_inode_dirty(). But it looks like all
users of simple_write_end() are memory-bound pseudo filesystems, who
could careless about mark_inode_dirty(). I might submit a
warning-comment patch to simple_write_end() in future.
CC: Stable <stable@kernel.org>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Some on disk exofs constants and types are defined in the pnfs_osd_xdr.h
file. Since we needed these types before the pnfs-objects code was
accepted to mainline we duplicated the minimal needed definitions into
an exofs local header. The definitions where conditionally included
depending on !CONFIG_PNFS defined. So if PNFS was present in the tree
definitions are taken from there and if not they are defined locally.
That was all good but, the CONFIG_PNFS is planed to be included upstream
before the pnfs-objects is also included. (The first pnfs batch might be
pnfs-files only)
So condition exofs local definitions on the absence of pnfs_osd_xdr.h
inclusion (__PNFS_OSD_XDR_H__ not defined). User code must make sure
that in future pnfs_osd_xdr.h will be included before fs/exofs/pnfs.h,
which happens to be so in current code.
Once pnfs-objects hits mainline, exofs's local header will be removed.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
When we remove an xattr, we call lookup_and_delete_xattr()
that takes some private xattr inodes mutexes. But we hold
the reiserfs lock at this time, which leads to dependency
inversions.
We can safely call lookup_and_delete_xattr() without the
reiserfs lock, where xattr inodes lookups only need the
xattr inodes mutexes.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Christian Kujau <lists@nerdbynature.de>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
On chown, reiserfs will call reiserfs_setattr() to change the owner
of the given inode, but it may also recursively call
reiserfs_setattr() to propagate the owner change to the private xattr
files for this inode.
Hence, the reiserfs lock may be acquired twice which is not wanted
as reiserfs_setattr() calls journal_begin() that is going to try to
relax the lock in order to safely acquire the journal mutex.
Using reiserfs_write_lock_once() from reiserfs_setattr() solves
the problem.
This fixes the following warning, that precedes a lockdep report.
WARNING: at fs/reiserfs/lock.c:95 reiserfs_lock_check_recursive+0x3f/0x50()
Hardware name: MS-7418
Unwanted recursive reiserfs lock!
Pid: 4189, comm: fsstress Not tainted 2.6.33-rc2-tip-atom+ #195
Call Trace:
[<c1178bff>] ? reiserfs_lock_check_recursive+0x3f/0x50
[<c1178bff>] ? reiserfs_lock_check_recursive+0x3f/0x50
[<c103f7ac>] warn_slowpath_common+0x6c/0xc0
[<c1178bff>] ? reiserfs_lock_check_recursive+0x3f/0x50
[<c103f84b>] warn_slowpath_fmt+0x2b/0x30
[<c1178bff>] reiserfs_lock_check_recursive+0x3f/0x50
[<c1172ae3>] do_journal_begin_r+0x83/0x350
[<c1172f2d>] journal_begin+0x7d/0x140
[<c106509a>] ? in_group_p+0x2a/0x30
[<c10fda71>] ? inode_change_ok+0x91/0x140
[<c115007d>] reiserfs_setattr+0x15d/0x2e0
[<c10f9bf3>] ? dput+0xe3/0x140
[<c1465adc>] ? _raw_spin_unlock+0x2c/0x50
[<c117831d>] chown_one_xattr+0xd/0x10
[<c11780a3>] reiserfs_for_each_xattr+0x113/0x2c0
[<c1178310>] ? chown_one_xattr+0x0/0x10
[<c14641e9>] ? mutex_lock_nested+0x2a9/0x350
[<c117826f>] reiserfs_chown_xattrs+0x1f/0x60
[<c106509a>] ? in_group_p+0x2a/0x30
[<c10fda71>] ? inode_change_ok+0x91/0x140
[<c1150046>] reiserfs_setattr+0x126/0x2e0
[<c1177c20>] ? reiserfs_getxattr+0x0/0x90
[<c11b0d57>] ? cap_inode_need_killpriv+0x37/0x50
[<c10fde01>] notify_change+0x151/0x330
[<c10e659f>] chown_common+0x6f/0x90
[<c10e67bd>] sys_lchown+0x6d/0x80
[<c1002ccc>] sysenter_do_call+0x12/0x32
---[ end trace 7c2b77224c1442fc ]---
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Christian Kujau <lists@nerdbynature.de>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
This reverts commit ae1b22f6e4.
As Linus said in 982d007a6ee: "There was something really messy about
cmpxchg8b and clone CPU's, so if you enable it on other CPUs later, do it
carefully."
This breaks lguest for those configs, but we can fix that by emulating
if we have to.
Fixes: http://bugzilla.kernel.org/show_bug.cgi?id=14884
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <201001051248.49700.rusty@rustcorp.com.au>
Cc: stable@kernel.org
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
The Correcteable/Uncorrectable Error Mask Registers are used by PCIe AER
driver which will controls the reporting of individual errors to PCIe RC
via PCIe error messages.
If hardware masks special error reporting to RC, the aer_inject driver
should not inject aer error.
Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Youquan, Song <youquan.song@intel.com>
Acked-by: Ying, Huang <ying.huang@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
It turns out that some PCI devices require extra delays when changing
power state from D3 to D0 (and the other way around). Although this
is against the PCI specification, we can handle it quite easily by
allowing drivers to define arbitrary D3 delays for devices known to
require extra time for switching power states.
Introduce additional field d3_delay in struct pci_dev and use it to
store the value of the device's D0->D3 delay, in miliseconds. Make
the PCI PM core code use the per-device d3_delay unless
pci_pm_d3_delay is greater (in which case the latter is used).
[This also allows the driver to specify d3_delay shorter than the
10 ms required by the PCI standard if the device is known to be able
to handle that.]
Make the sky2 driver set d3_delay to 150 for devices handled by it.
Fixes http://bugzilla.kernel.org/show_bug.cgi?id=14730 which is a
listed regression from 2.6.30.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
If perf events are active, we should not reset the %pcr to
PCR_PIC_PRIV. That perf events code does the management.
Signed-off-by: David S. Miller <davem@davemloft.net>
In bbc_envctrl_init() we have to unlink the fan and temp instances
from the lists because our caller is going to free up the 'bp' object
if we return an error.
We can't rely upon bbc_envctrl_cleanup() to do this work for us in
this case.
Reported-by: Patrick Finnegan <pat@computer-refuge.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit e0cd516 "PCI: derive nearby CPUs from device's instead of bus'
NUMA information" causes an null pointer dereference when reading from
the sysfs attributes local_cpu* on Intel machines with no ACPI NUMA
proximity info, since dev->numa_node gets set to -1 for all PCI devices,
which then gets passed to cpumask_of_node.
Add a check to prevent this.
Signed-off-by: David John <davidjon@xenontk.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
It is above 0x100 (PCI-Express extended register space), so if mmconf
is not enable, we can't access it.
[ hpa: changed the bound from 0x200 to 0x120, which is the tight
bound. ]
Reported-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <1261525263-13763-3-git-send-email-yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
fix for error that is introduced by
| x86: Use find_e820() instead of hard coded trampoline address
it should end with PAGE_SIZE + PAGE_SIZE
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <1261525263-13763-2-git-send-email-yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Holding locks over device_del -> kobject_del -> sysfs_deactivate can
cause deadlocks if those same locks are grabbed in sysfs show or store
methods.
The I model s_active count + completion as a sleeping read/write lock.
I describe to lockdep sysfs_get_active as a read_trylock,
sysfs_put_active as a read_unlock, and sysfs_deactivate as a
write_lock and write_unlock pair. This seems to capture the essence
for purposes of finding deadlocks, and in my testing gives finds real
issues and ignores non-issues.
This brings us back to holding locks over kobject_del is a problem
that ideally we should find a way of addressing, but at least lockdep
can tell us about the problems instead of requiring developers to debug
rare strange system deadlocks, that happen when sysfs files are removed
while being written to.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Zhao Yakui