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The linux build-bot recently reported a build error in arch/mips/kernel/vpe.c
tree: git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-linus
head: 261000a56b6382f597bcb12000f55c9ff26a1efb
commit: 261000a56b6382f597bcb12000f55c9ff26a1efb [4/4] userns: userns: Remove UIDGID_STRICT_TYPE_CHECKS
config: make ARCH=mips maltaaprp_defconfig
All error/warnings:
arch/mips/kernel/vpe.c: In function 'vpe_open':
>> arch/mips/kernel/vpe.c:1086:9: error: incompatible types when assigning to type 'unsigned int' from type 'kuid_t'
>> arch/mips/kernel/vpe.c:1087:9: error: incompatible types when assigning to type 'unsigned int' from type 'kgid_t'
vim +1086 arch/mips/kernel/vpe.c
863abad4 Jesper Juhl 2010-10-30 1080 return -ENOMEM;
863abad4 Jesper Juhl 2010-10-30 1081 }
e01402b1 Ralf Baechle 2005-07-14 1082 v->plen = P_SIZE;
e01402b1 Ralf Baechle 2005-07-14 1083 v->load_addr = NULL;
e01402b1 Ralf Baechle 2005-07-14 1084 v->len = 0;
e01402b1 Ralf Baechle 2005-07-14 1085
d76b0d9b David Howells 2008-11-14 @1086 v->uid = filp->f_cred->fsuid;
d76b0d9b David Howells 2008-11-14 @1087 v->gid = filp->f_cred->fsgid;
2600990e Ralf Baechle 2006-04-05 1088
2600990e Ralf Baechle 2006-04-05 1089 v->cwd[0] = 0;
2600990e Ralf Baechle 2006-04-05 1090 ret = getcwd(v->cwd, VPE_PATH_MAX);
When examining the code to see what v->uid and v->gid were used for I
discovered that the only users in the kernel are vpe_getuid and
vpe_getgid, and that vpe_getuid and vpe_getgid are never called.
So instead of proposing a conversion to use kuid_t and kgid_t instead
of unsigned int/int as I normally would let's just kill this dead code
so no one has to worry about it further.
Deng-Cheng Zhu said:
This is a good catch. vpe_get[u|g]id was originally used by KSPD which
has been removed.
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Reviewed-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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If a node page is trucated, we'd better drop the page in the node_inode's page
cache for better memory footprint.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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This patch adds missing 'void' to functions that doesn't receive
arguments.
Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
Link: http://lkml.kernel.org/r/1390429369-13761-1-git-send-email-david.a.cohen@linux.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Commit bc20aa48bbb3068224a1c91f8332971fdb689fad ("x86, intel-mid:
Add Merrifield platform support") added new instances of __cpuinit
usage. We removed this a couple versions ago; we now want to remove
the compat no-op stubs. Introducing new users is not what we want to
see at this point in time, as it will break once the stubs are gone.
This also fixes an out of sync __init vs. __cpuinit -- as the former
is real, and the latter is a no-op; hence it would have been a section
mismatch.
Cc: Fei Yang <fei.yang@intel.com>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: David Cohen <david.a.cohen@linux.intel.com>
Link: http://lkml.kernel.org/r/1390412125-19439-1-git-send-email-paul.gortmaker@windriver.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Commit 85611e3febe78955a519f5f9eb47b941525c8c76 ("x86, intel-mid:
Add Clovertrail platform support") added new instances of __cpuinit
usage. We removed this a couple versions ago; we now want to remove
the compat no-op stubs. Introducing new users is not what we want to
see at this point in time, as it will break once the stubs are gone.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: Fei Yang <fei.yang@intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: David Cohen <david.a.cohen@linux.intel.com>
Link: http://lkml.kernel.org/r/1390412055-19341-1-git-send-email-paul.gortmaker@windriver.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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This was a "forgotten" branch of tty fixes that somehow didn't make it
into my "main" branches, my fault.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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open/release operations require userspace transitions to keep track
of the open count and to perform any FS-specific setup. However,
for some purely read-only FSs which don't need to perform any setup
at open/release time, we can avoid the performance overhead of
calling into userspace for open/release calls.
This patch adds the necessary support to the fuse kernel modules to prevent
open/release operations from hitting in userspace. When the client returns
ENOSYS, we avoid sending the subsequent release to userspace, and also
remember this so that future opens also don't trigger a userspace
operation.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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Various read operations (e.g. readlink, readdir) invalidate the cached
attrs for atime changes. This patch adds a new function
'fuse_invalidate_atime', which checks for a read-only super block and
avoids the attr invalidation in that case.
Signed-off-by: Andrew Gallagher <andrewjcg@fb.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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As noticed by Coverity the "num != 0" condition never triggers. Instead it
should check for a complete page.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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Having this struct in module memory could Oops when if the module is
unloaded while the buffer still persists in a pipe.
Since sock_pipe_buf_ops is essentially the same as fuse_dev_pipe_buf_steal
merge them into nosteal_pipe_buf_ops (this is the same as
default_pipe_buf_ops except stealing the page from the buffer is not
allowed).
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org
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'for-3.14/sensor-hub', 'for-3.14/sony' and 'for-3.14/upstream' into for-linus
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Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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With b8668fd0a7e1b59f "s390/uapi: change struct statfs[64] member types
to unsigned values" the size of a couple of struct statfs64 member got
incorrectly changed from 64 to 32 bit for 32 bit builds.
Fix this by changing the type of couple of struct statfs64 members from
unsigned long to unsigned long long.
The definition of struct compat_statfs64 was correct however.
Cc: stable@vger.kernel.org # v3.10+
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Remove some dead uaccess extern declarations and also make some functions
static, since they are only used locally.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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If get_fs() == USER_DS we better test if current->mm is not zero before
walking page tables.
The page table walk code would try to lock mm->page_table_lock, however
if mm is zero this might crash.
Now it is arguably incorrect trying to access userspace if current->mm
is zero, however we have seen that and s390 would be the only architecture
which would crash in such a case.
So we better make the page table walk code a bit more robust and report
always a fault instead.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Get rid of this link error:
arch/s390/built-in.o: In function `smp_prepare_cpus':
(.init.text+0x301e): undefined reference to `dump_save_area_create'
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Fix broken inline assembly contraints for cmpxchg64 on 32bit.
Fixes this crash:
specification exception: 0006 [#1] SMP
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.13.0 #4
task: 005a16c8 ti: 00592000 task.ti: 00592000
Krnl PSW : 070ce000 8029abd6 (lockref_get+0x3e/0x9c)
...
Krnl Code: 8029abcc: a71a0001 ahi %r1,1
8029abd0: 1852 lr %r5,%r2
#8029abd2: bb40f064 cds %r4,%r0,100(%r15)
>8029abd6: 1943 cr %r4,%r3
8029abd8: 1815 lr %r1,%r5
Call Trace:
([<0000000078e01870>] 0x78e01870)
[<000000000021105a>] sysfs_mount+0xd2/0x1c8
[<00000000001b551e>] mount_fs+0x3a/0x134
[<00000000001ce768>] vfs_kern_mount+0x44/0x11c
[<00000000001ce864>] kern_mount_data+0x24/0x3c
[<00000000005cc4b8>] sysfs_init+0x74/0xd4
[<00000000005cb5b4>] mnt_init+0xe0/0x1fc
[<00000000005cb16a>] vfs_caches_init+0xb6/0x14c
[<00000000005be794>] start_kernel+0x318/0x33c
[<000000000010001c>] _stext+0x1c/0x80
Reported-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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During parsing of the sizes array the pointer to the particular
string is lost. Keep it by using an extra pointer to store the end
position of the parsed string. Keeping these parameters accessible
can be helpful for debugging purposes and for userspace reading
the parameters at runtime via sysfs. Also this will ensure that the
memory is freed at module unload time.
Reported-by: Michael Veigel <veigel@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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This part of the ep11 patch should not have been merged.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Add the generic "lnxhvc" terminal ID to automatically assign a HVC terminal when
connecting to the HVC IUCV terminal device driver. The terminal device driver
tries to find a free (not connected) HVC terminal to satisfy the incoming
connection request.
With this improvement, you do not longer need to guess which HVC terminal is
free, that is, not connected. Also you can still connect to a particular HVC
terminal by using its associated terminal ID.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Add device attributes to display details about the connection status
of HVC IUCV terminals.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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drivers/tty/hvc/hvc_iucv.c:131:25: warning: symbol 'hvc_iucv_get_private' was not
declared. Should it be static?
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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When creating the virtual unit record (UR) device, specify the parent
CCW device.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Nothing's changed here; we just need to bump the generation check.
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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This patch adds NODE_MAPPING which is similar as META_MAPPING introduced by
Gu Zheng.
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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As the orphan_blocks may be max to 504, so it is not security
and rigorous to store such a large array in the kernel stack
as Dan Carpenter said.
In fact, grab_meta_page has locked the page in the page cache,
and we can use find_get_page() to fetch the page safely in the
downstream, so we can remove the page array directly.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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Introduce help function META_MAPPING() to get the cache meta blocks'
address space.
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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This patch moves a function in f2fs_delete_entry for code readability.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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If a dentry page is updated, we should call mark_inode_dirty to add the inode
into the dirty list, so that its dentry pages are flushed to the disk.
Otherwise, the inode can be evicted without flush.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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Since an old pageflip will keep its scanout buffer object pinned until
it has executed its unpin task on the common workqueue, we can clog up
our GGTT with stale pinned objects. As we cannot flush those workqueues
without dropping our locks, we have to resort to falling back to
userspace and telling them to repeat the operation in order to have a
chance to run our workqueues and free up the required memory. If we
fail, then we are forced to report ENOSPC back to userspace causing the
operation to fail and best-case scenario is that it introduces temporary
corruption.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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On older generations (gen2, gen3) the GPU requires fences for many
operations, such as blits. The display hardware also requires fences for
scanouts and this leads to a situation where an arbitrary number of
fences may be pinned by old scanouts following a pageflip but before we
have executed the unpin workqueue. This is unpredictable by userspace
and leads to random EDEADLK when submitting an otherwise benign
execbuffer. However, we can detect when we have an outstanding flip and
so cause userspace to wait upon their completion before finally
declaring that the system is starved of fences. This is really no worse
than forcing the GPU to stall waiting for older execbuffer to retire and
release their fences before we can reallocate them for the next
execbuffer.
v2: move the test for a pending fb unpin to a common routine for
later reuse during eviction
Reported-and-tested-by: dimon@gmx.net
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=73696
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Atm after a failed link training we disable the DP port. This can happen
during a modeset-enable or a DP link re-establishment. The latter can be
a problem and we shouldn't disable the DP port, see the previous patch for
the reasoning. In the former case the right thing would be to disable
the DP port, but also the rest of the pipe.
As a stop-gap solution leave the DP port enabled in both cases. It is an
improvement on its own (avoiding HW lock ups) and the proper solution
for the first case requires a bigger change, so let's keep that on the
TODO list.
v2:
- fix explanation of change impact (Chris)
Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Currently if the DP link is lost (either because of a hot unplug, or
failed link status check) we disable the DP port, but leave the rest
of the pipe running. This is incompatible with the modeset disabling
sequence of some platforms/configurations. At least this is the case for
DP ports on the CPU as opposed to PCH.
Atm we'll also get a warning when we do a modeset disable after the
above link lost event, since we expect the DP port to be enabled at this
point (see the bugzilla ticket for the related dmesg).
Note that with this patch we'll still end up disabling the port, thanks
to the HPD uevent and subsequent modeset disable.
See also the next patch fixing the other half of this issue.
Solution suggested by Ville.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70570
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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My 855gm doesn't register the intel backlight but it still ends up
calling the backlight code to enable/disable the backlight via the
LVDS code. This leads to some WARNs due to backlight.max being 0.
Let's have intel_panel_enable_backlight() and intel_panel_disable_backlight()
check whether there's a backlight present or not.
Also move the backlight.present check from asle_set_backlight() into
intel_panel_set_backlight() for some extra symmetry.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Fix typo possibly leading to timed out DP aux transactions on ports C,D.
Introduced in:
Commmit 4aeebd7443e36b0a40032e518a9338f48bd27efc
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Thu Oct 31 09:53:36 2013 +0100
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=72210
Signed off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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We need to defer the free request until the object/vma is capable of
being freed - or else we have a problem when we try to destroy the
context.
The exact same issue is described and fixed here:
commit e20780439b26ba95aeb29d3e27cd8cc32bc82a4c
Author: Ben Widawsky <ben@bwidawsk.net>
Date: Fri Dec 6 14:11:22 2013 -0800
drm/i915: Defer request freeing
I had this fix previously, but decided not to keep it for some reason I
can no longer remember.
gem_reset_stats is a really good test at hitting the problem.
For the inquisitive:
[ 170.516392] ------------[ cut here ]------------
[ 170.517227] WARNING: CPU: 1 PID: 105 at drivers/gpu/drm/drm_mm.c:578 drm_mm_takedown+0x2e/0x30 [drm]()
[ 170.518064] Memory manager not clean during takedown.
[ 170.518941] CPU: 1 PID: 105 Comm: kworker/1:1 Not tainted 3.13.0-rc4-BEN+ #28
[ 170.519787] Hardware name: Hewlett-Packard HP EliteBook 8470p/179B, BIOS 68ICF Ver. F.02 04/27/2012
[ 170.520662] Call Trace:
[ 170.521517] [<ffffffff814f0589>] dump_stack+0x4e/0x7a
[ 170.522373] [<ffffffff81049e6d>] warn_slowpath_common+0x7d/0xa0
[ 170.523227] [<ffffffff81049edc>] warn_slowpath_fmt+0x4c/0x50
[ 170.524079] [<ffffffffa06c414e>] drm_mm_takedown+0x2e/0x30 [drm]
[ 170.524934] [<ffffffffa07213f3>] gen6_ppgtt_cleanup+0x23/0x110
[i915]
[ 170.525777] [<ffffffffa07837ed>] ppgtt_release.part.5+0x24/0x29
[i915]
[ 170.526603] [<ffffffffa071aaa5>] i915_gem_context_free+0x195/0x1a0
[i915]
[ 170.527423] [<ffffffffa071189d>] i915_gem_free_request+0x9d/0xb0
[i915]
[ 170.528247] [<ffffffffa0718af9>] i915_gem_reset+0x1f9/0x3f0 [i915]
[ 170.529065] [<ffffffffa0700cce>] i915_reset+0x4e/0x180 [i915]
[ 170.529870] [<ffffffffa070829d>] i915_error_work_func+0xcd/0x120
[i915]
[ 170.530666] [<ffffffff8106c13a>] process_one_work+0x1fa/0x6d0
[ 170.531453] [<ffffffff8106c0d8>] ? process_one_work+0x198/0x6d0
[ 170.532230] [<ffffffff8106c72b>] worker_thread+0x11b/0x3a0
[ 170.532996] [<ffffffff8106c610>] ? process_one_work+0x6d0/0x6d0
[ 170.533771] [<ffffffff810743ef>] kthread+0xff/0x120
[ 170.534548] [<ffffffff810742f0>] ? insert_kthread_work+0x80/0x80
[ 170.535322] [<ffffffff814f97ac>] ret_from_fork+0x7c/0xb0
[ 170.536089] [<ffffffff810742f0>] ? insert_kthread_work+0x80/0x80
[ 170.536847] ---[ end trace 3d4c12892e42d58f ]---
v2: Whitespace fix. (Chris)
Note: This is a bug that only hits the ppgtt topic branch but I've
figured that doing the request cleanup in this order is generally the
right thing to do.
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
[danvet: Add a code comment to clarify what's actually going on since
the lifetime rules aroung ppgtt cleanup are ... fuzzy a best atm. Also
add a note about why we need this.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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The opregion notification for runtime suspend is currently D1, not D3.
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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It ought to work ok in 3.14. We have some fun stuff coming after that,
but all the basics are in place now and seem relatively stable.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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This is user-triggerable and hence we should not allow it to spam
dmesg. Also, it upsets the nice dmesg tracking piglit does.
Note that this is just extra debugging information, mostly
unwanted, in case of a hang and that there is a separate message to the
user giving instructions on how to report a bug for a GPU hang.
v2: Add note as suggests in Chris' reply.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=72740
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Missing "@" in include/linux/wait.h cause "make htmldocs" failed
with following warning messages.
Warning(/home/iida/Repo/linux-next//include/linux/wait.h:304):
No description found for parameter 'cmd1'
Warning(/home/iida/Repo/linux-next//include/linux/wait.h:304):
No description found for parameter 'cmd2'
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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A couple patches in the upcoming rework of semaphores will break if
semaphores are toggled by the user at various times. Since the code
cleanups there seem to be an overall win, and toggling semaphores at
runtime is not a terribly useful thing to do, simply make the module
parameter read-only.
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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The ring will emit too many if semaphores are disabled since we do not
add the correct number to num_dwords anymore.
This was introduced:
commit 52ed23253b68e1cf154b03d91bed619504cf955b
Author: Ben Widawsky <benjamin.widawsky@intel.com>
Date: Mon Dec 16 20:50:38 2013 -0800
drm/i915: Don't emit mbox updates without semaphores
FWIW, the bug was fixed later in the series.
/me hangs head in shame.
Daniel: Also note that we should have merged the read-only semaphore
modparam before this patch.
Reported-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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While trying to find a random -EINVAL from a failing test, I noticed we
had a few hard to follow return values.
The first two hunks in this patch replace completely useless
initialization of ret. The last several hunks help to distinguish
between altering 'return ret' and 'return <ERROR>'
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Hannes Frederic Sowa says:
====================
reciprocal_divide update
This patch is on top of aee636c4809fa5 ("bpf: do not use reciprocal
divide") from Eric that sits in net tree. It will not create a merge
conflict, but it depends on this one, so we suggest, if possible, to
merge net into net-next.
We are proposing this change with only small modifications from the
v2 version, namely updating the name of trim to reciprocal_scale
(as commented on by Ben Hutchings and Eric Dumazet, thanks!).
We thought about introducing the reciprocal_divide algorithm in
parallel to the one already used by the kernel but faced organizational
issues, leading us to the conclusion that it is best to just replace
the old one: We could not come up with names for the different
implementations and also with a way to describe the differences to
guide developers which one to choose in which situation. This is
because we cannot specify the correct semantics for the version
which is currently used by the kernel. Altough it seems to not be
causing problems in the kernel, we cannot surely say so in the
case of flex_array for the future. Current usage seems ok, but
future users could run into problems.
Changelog:
v1->v2:
- changed name to prandom_u32_max in p1
- changed name to trim in p2
- reworked code in p3
v2->v3:
- p1 and p3 stays unchanged, only small update in commit
message in p3
- changed name to reciprocal_scale in p2
- fixed kernel doc format
v3->v4:
- pseduo -> pseudo (thanks to Tilman Schmidt)
v4->v5:
- fix pseduo -> pseudo for real now, sorry for the noise
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
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Jakub Zawadzki noticed that some divisions by reciprocal_divide()
were not correct [1][2], which he could also show with BPF code
after divisions are transformed into reciprocal_value() for runtime
invariance which can be passed to reciprocal_divide() later on;
reverse in BPF dump ended up with a different, off-by-one K in
some situations.
This has been fixed by Eric Dumazet in commit aee636c4809fa5
("bpf: do not use reciprocal divide"). This follow-up patch
improves reciprocal_value() and reciprocal_divide() to work in
all cases by using Granlund and Montgomery method, so that also
future use is safe and without any non-obvious side-effects.
Known problems with the old implementation were that division by 1
always returned 0 and some off-by-ones when the dividend and divisor
where very large. This seemed to not be problematic with its
current users, as far as we can tell. Eric Dumazet checked for
the slab usage, we cannot surely say so in the case of flex_array.
Still, in order to fix that, we propose an extension from the
original implementation from commit 6a2d7a955d8d resp. [3][4],
by using the algorithm proposed in "Division by Invariant Integers
Using Multiplication" [5], Torbjörn Granlund and Peter L.
Montgomery, that is, pseudocode for q = n/d where q, n, d is in
u32 universe:
1) Initialization:
int l = ceil(log_2 d)
uword m' = floor((1<<32)*((1<<l)-d)/d)+1
int sh_1 = min(l,1)
int sh_2 = max(l-1,0)
2) For q = n/d, all uword:
uword t = (n*m')>>32
q = (t+((n-t)>>sh_1))>>sh_2
The assembler implementation from Agner Fog [6] also helped a lot
while implementing. We have tested the implementation on x86_64,
ppc64, i686, s390x; on x86_64/haswell we're still half the latency
compared to normal divide.
Joint work with Daniel Borkmann.
[1] http://www.wireshark.org/~darkjames/reciprocal-buggy.c
[2] http://www.wireshark.org/~darkjames/set-and-dump-filter-k-bug.c
[3] https://gmplib.org/~tege/division-paper.pdf
[4] http://homepage.cs.uiowa.edu/~jones/bcd/divide.html
[5] http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1.2556
[6] http://www.agner.org/optimize/asmlib.zip
Reported-by: Jakub Zawadzki <darkjames-ws@darkjames.pl>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Austin S Hemmelgarn <ahferroin7@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: Jesse Gross <jesse@nicira.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Andy Gospodarek <andy@greyhouse.net>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Jakub Zawadzki <darkjames-ws@darkjames.pl>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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As David Laight suggests, we shouldn't necessarily call this
reciprocal_divide() when users didn't requested a reciprocal_value();
lets keep the basic idea and call it reciprocal_scale(). More
background information on this topic can be found in [1].
Joint work with Hannes Frederic Sowa.
[1] http://homepage.cs.uiowa.edu/~jones/bcd/divide.html
Suggested-by: David Laight <david.laight@aculab.com>
Cc: Jakub Zawadzki <darkjames-ws@darkjames.pl>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Many functions have open coded a function that returns a random
number in range [0,N-1]. Under the assumption that we have a PRNG
such as taus113 with being well distributed in [0, ~0U] space,
we can implement such a function as uword t = (n*m')>>32, where
m' is a random number obtained from PRNG, n the right open interval
border and t our resulting random number, with n,m',t in u32 universe.
Lets go with Joe and simply call it prandom_u32_max(), although
technically we have an right open interval endpoint, but that we
have documented. Other users can further be migrated to the new
prandom_u32_max() function later on; for now, we need to make sure
to migrate reciprocal_divide() users for the reciprocal_divide()
follow-up fixup since their function signatures are going to change.
Joint work with Hannes Frederic Sowa.
Cc: Jakub Zawadzki <darkjames-ws@darkjames.pl>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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