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Remove the use of arch_setup_dma_ops() that was not exported
and was breaking loadable module compilation.
Signed-off-by: Madalin Bucur <madalin.bucur@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Make sure dma_ops are set, to be later used by the Ethernet driver.
Signed-off-by: Madalin Bucur <madalin.bucur@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Since commit 217f69743681 ("net: busy-poll: allow preemption in
sk_busy_loop()") there is an explicit do_softirq() invocation after
local_bh_enable() has been invoked.
I don't understand why we need this because local_bh_enable() will
invoke do_softirq() once the softirq counter reached zero and we have
softirq-related work pending.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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We should avoid marking goto rules unresolved when their
target is actually reachable after rule deletion.
Consolder following sample scenario:
# ip -4 ru sh
0: from all lookup local
32000: from all goto 32100
32100: from all lookup main
32100: from all lookup default
32766: from all lookup main
32767: from all lookup default
# ip -4 ru del pref 32100 table main
# ip -4 ru sh
0: from all lookup local
32000: from all goto 32100 [unresolved]
32100: from all lookup default
32766: from all lookup main
32767: from all lookup default
After removal of first rule with preference 32100 we
mark all goto rules as unreachable, even when rule with
same preference as removed one still present.
Check if next rule with same preference is available
and make all rules with goto action pointing to it.
Signed-off-by: Serhey Popovych <serhe.popovych@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Fixes resume from suspend.
bug: https://bugzilla.kernel.org/show_bug.cgi?id=196121
Reported-by: Przemek <soprwa@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
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Disable PX on these systems.
bug: https://bugs.freedesktop.org/show_bug.cgi?id=101491
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
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Increase the default display clock on newer asics to
accomodate some high res modes with really high refresh
rates.
bug: https://bugs.freedesktop.org/show_bug.cgi?id=93826
Acked-by: Chunming Zhou <david1.zhou@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
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We were using the wrong structure which lead to an overflow
on some boards.
bug: https://bugs.freedesktop.org/show_bug.cgi?id=101387
Acked-by: Chunming Zhou <david1.zhou@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
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Clock name has been updated during driver/DT binding review:
https://lkml.org/lkml/2016/12/13/718
Update DT binding doc to reflect this.
Fixes: 8f9359c6c6a0 (dt-bindings: mfd: Add bindings for STM32 Timers driver)
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
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Curious as to what this was for I looked at /usr/include/ and only some
python headers define this, and it ends up being to enable "extensions"
on some old OSes:
/* Enable extensions on AIX 3, Interix */
I guess we can remove this one safely.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-omnundlxo2brs552bdl6m0j1@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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While trying to reduce util.[ch] I noticed that fetch_kernel_version()
and fetch_ubuntu_kernel_version() do lots of operations only to check if
they are needed, i.e. it checks if the pointer where to return the
kernel version is NULL only after obtaining the kernel version from
/proc/version_signature or by parsing the results from uname().
Do it earlier not to confuse people reading this code in the future :-)
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-i94qwyekk4tzbu0b9ce1r1mz@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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And make it static, nobody else uses it, if we ever need it in more
places we can carve a new source file for process related methods,
for now lets reduce util.{c,h} a tad more.
Link: http://lkml.kernel.org/n/tip-zgb28rllvypjibw52aaz9p15@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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This commit fixes a "maybe-uninitialized" build failure in
arch/mips/kvm/tlb.c when KVM, DYNAMIC_DEBUG and JUMP_LABEL are all
enabled. The failure is:
In file included from ./include/linux/printk.h:329:0,
from ./include/linux/kernel.h:13,
from ./include/asm-generic/bug.h:15,
from ./arch/mips/include/asm/bug.h:41,
from ./include/linux/bug.h:4,
from ./include/linux/thread_info.h:11,
from ./include/asm-generic/current.h:4,
from ./arch/mips/include/generated/asm/current.h:1,
from ./include/linux/sched.h:11,
from arch/mips/kvm/tlb.c:13:
arch/mips/kvm/tlb.c: In function ‘kvm_mips_host_tlb_inv’:
./include/linux/dynamic_debug.h:126:3: error: ‘idx_kernel’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
__dynamic_pr_debug(&descriptor, pr_fmt(fmt), \
^~~~~~~~~~~~~~~~~~
arch/mips/kvm/tlb.c:169:16: note: ‘idx_kernel’ was declared here
int idx_user, idx_kernel;
^~~~~~~~~~
There is a similar error relating to "idx_user". Both errors were
observed with GCC 6.
As far as I can tell, it is impossible for either idx_user or idx_kernel
to be uninitialized when they are later read in the calls to kvm_debug,
but to satisfy the compiler, add zero initializers to both variables.
Signed-off-by: James Cowgill <James.Cowgill@imgtec.com>
Fixes: 57e3869cfaae ("KVM: MIPS/TLB: Generalise host TLB invalidate to kernel ASID")
Cc: <stable@vger.kernel.org> # 4.11+
Acked-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
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Return EAGAIN if any of the following checks fail
+ i_rwsem is not lockable
+ NODATACOW or PREALLOC is not set
+ Cannot nocow at the desired location
+ Writing beyond end of file which is not allocated
Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If IOCB_NOWAIT is set, bail if the i_rwsem is not lockable
immediately.
IF IOMAP_NOWAIT is set, return EAGAIN in xfs_file_iomap_begin
if it needs allocation either due to file extension, writing to a hole,
or COW or waiting for other DIOs to finish.
Return -EAGAIN if we don't have extent list in memory.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Return EAGAIN if any of the following checks fail for direct I/O:
+ i_rwsem is lockable
+ Writing beyond end of file (will trigger allocation)
+ Blocks are not allocated at the write location
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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A new bio operation flag REQ_NOWAIT is introduced to identify bio's
orignating from iocb with IOCB_NOWAIT. This flag indicates
to return immediately if a request cannot be made instead
of retrying.
Stacked devices such as md (the ones with make_request_fn hooks)
currently are not supported because it may block for housekeeping.
For example, an md can have a part of the device suspended.
For this reason, only request based devices are supported.
In the future, this feature will be expanded to stacked devices
by teaching them how to handle the REQ_NOWAIT flags.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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IOCB_NOWAIT translates to IOMAP_NOWAIT for iomaps.
This is used by XFS in the XFS patch.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Find out if the I/O will trigger a wait due to writeback. If yes,
return -EAGAIN.
Return -EINVAL for buffered AIO: there are multiple causes of
delay such as page locks, dirty throttling logic, page loading
from disk etc. which cannot be taken care of.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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RWF_NOWAIT informs kernel to bail out if an AIO request will block
for reasons such as file allocations, or a writeback triggered,
or would block while allocating requests while performing
direct I/O.
RWF_NOWAIT is translated to IOCB_NOWAIT for iocb->ki_flags.
FMODE_AIO_NOWAIT is a flag which identifies the file opened is capable
of returning -EAGAIN if the AIO call will block. This must be set by
supporting filesystems in the ->open() call.
Filesystems xfs, btrfs and ext4 would be supported in the following patches.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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aio_rw_flags is introduced in struct iocb (using aio_reserved1) which will
carry the RWF_* flags. We cannot use aio_flags because they are not
checked for validity which may break existing applications.
Note, the only place RWF_HIPRI comes in effect is dio_await_one().
All the rest of the locations, aio code return -EIOCBQUEUED before the
checks for RWF_HIPRI.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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filemap_range_has_page() return true if the file's mapping has
a page within the range mentioned. This function will be used
to check if a write() call will cause a writeback of previous
writes.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Also added RWF_SUPPORTED to encompass all flags.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-linus
Pull xen-blkback fixes from Konrad:
"Security and memory leak fixes in xen block driver."
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git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc
* fix problems that could cause hangs or crashes in the host on POWER9
* fix problems that could allow guests to potentially affect or disrupt
the execution of the controlling userspace
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As it turns out more than just Armada 370 and XP support using GPIO
lines as PWM lines. For example the Armada 38x family has the same
hardware support. As such "marvell,armada-370-xp-gpio" for the
compatible string is a misnomer.
Change the compatible string to "marvell,armada-370-gpio" before the
driver makes it out of the -rc stage. This also follows the practice of
using only the first device family supported as part of the name.
Also update the documentation and comments in the code accordingly.
Fixes: 757642f9a584 ("gpio: mvebu: Add limited PWM support")
Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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Put __startup_64() and fixup_pointer() into .head.text section to make
sure it's always near startup_64() and always callable.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel test robot <fengguang.wu@intel.com>
Cc: wfg@linux.intel.com
Link: http://lkml.kernel.org/r/20170616113024.ajmif63cmcszry5a@black.fi.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Normally, when the initrd is gone, we can't search it for microcode
blobs to apply anymore. For that we need to stash away the patch in our
own storage.
And save_microcode_in_initrd_intel() looks like the proper place to
do that from. So in order for early loading to work, invalidate the
intel_ucode_patch pointer to the patch *before* scanning the initrd one
last time.
If the scanning code finds a microcode patch, it will assign that
pointer again, this time with our own storage's address.
This way, early microcode application during resume-from-RAM works too,
even after the initrd is long gone.
Tested-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170614140626.4462-2-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Early during boot, the BSP finds the ramdisk's position from boot_params
but by the time the APs get to boot, the BSP has continued in the mean
time and has potentially managed to relocate that ramdisk.
And in that case, the APs need to find the ramdisk at its new position,
in *physical* memory as they're running before paging has been enabled.
Thus, get the updated physical location of the ramdisk which is in the
relocated_ramdisk variable.
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170614140626.4462-1-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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We're supposed to exit the loop with "timeout" set to zero.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-janitors@vger.kernel.org
Fixes: 99e8b9ca90d6 ("x86, NMI: Add NMI IPI selftest")
Link: http://lkml.kernel.org/r/20170619105304.GA23995@elgon.mountain
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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https://git.linaro.org/people/daniel.lezcano/linux into timers/urgent
Pull clockevents fixes from Daniel Lezcano:
- Fixed wrong iomem area unmapped in the arch_arm_timer (Frank Rowand)
- Added missing includes for sun5i and cadence-ttc (Stephen Rothwell)
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This function was introduced by:
150593bf8693 ("sched/api: Introduce task_rcu_dereference() and try_get_task_struct()")
... to allow easier usage of task_rcu_dereference(), however no users
were ever added. Drop the helper.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Link: http://lkml.kernel.org/r/20170615023730.22827-1-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Conflicts:
kernel/sched/Makefile
Pick up the waitqueue related renames - it didn't get much feedback,
so it appears to be uncontroversial. Famous last words? ;-)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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If we set a next or last buddy for a se that is not on_rq, we will
end up taking a NULL pointer dereference in wakeup_preempt_entity
via pick_next_task_fair.
Detect when we would be about to do that, throw a warning and
then refuse to actually set it.
This has been suggested at least twice:
https://marc.info/?l=linux-kernel&m=146651668921468&w=2
https://lkml.org/lkml/2016/6/16/663
I recently had to debug a problem with these (we hadn't backported
Konstantin's patches in this area) and this would have saved a lot
of time/pain.
Just do it.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Cc: Ben Segall <bsegall@google.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170510201139.16236-1-dja@axtens.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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well
This definition of SCHED_WARN_ON():
#define SCHED_WARN_ON(x) ((void)(x))
is not fully compatible with the 'real' WARN_ON_ONCE() primitive, as it
has no return value, so it cannot be used in conditionals.
Fix it.
Cc: Daniel Axtens <dja@axtens.net>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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So I've noticed a number of instances where it was not obvious from the
code whether ->task_list was for a wait-queue head or a wait-queue entry.
Furthermore, there's a number of wait-queue users where the lists are
not for 'tasks' but other entities (poll tables, etc.), in which case
the 'task_list' name is actively confusing.
To clear this all up, name the wait-queue head and entry list structure
fields unambiguously:
struct wait_queue_head::task_list => ::head
struct wait_queue_entry::task_list => ::entry
For example, this code:
rqw->wait.task_list.next != &wait->task_list
... is was pretty unclear (to me) what it's doing, while now it's written this way:
rqw->wait.head.next != &wait->entry
... which makes it pretty clear that we are iterating a list until we see the head.
Other examples are:
list_for_each_entry_safe(pos, next, &x->task_list, task_list) {
list_for_each_entry(wq, &fence->wait.task_list, task_list) {
... where it's unclear (to me) what we are iterating, and during review it's
hard to tell whether it's trying to walk a wait-queue entry (which would be
a bug), while now it's written as:
list_for_each_entry_safe(pos, next, &x->head, entry) {
list_for_each_entry(wq, &fence->wait.head, entry) {
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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sched/core.c to sched/wait_bit.c
The key hashed waitqueue data structures and their initialization
was done in the main scheduler file for no good reason, move them
to sched/wait_bit.c instead.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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<linux/wait_bit.h>
The wait_bit*() types and APIs are mixed into wait.h, but they
are a pretty orthogonal extension of wait-queues.
Furthermore, only about 50 kernel files use these APIs, while
over 1000 use the regular wait-queue functionality.
So clean up the main wait.h by moving the wait-bit functionality
out of it, into a separate .h and .c file:
include/linux/wait_bit.h for types and APIs
kernel/sched/wait_bit.c for the implementation
Update all header dependencies.
This reduces the size of wait.h rather significantly, by about 30%.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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So there's over 300 CPP macro line-continuation backslashes in
include/linux/wait.h (!!), which are aligned vertically to make
the macro maze a bit more navigable.
The recent renames and reorganization broke some of them, and
instead of re-aligning them in every patch (which would add
a lot of stylistic noise to the patches and make them less
readable), I just ignored them - and fixed them up in a single
go in this patch.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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prototypes
Contrary to kernel tradition, most of the bit-wait function prototypes
in <linux/wait.h> don't fully define the parameter names, they only
list the types:
int out_of_line_wait_on_bit_timeout(void *, int, wait_bit_action_f *, unsigned, unsigned long);
... which is pretty passive-aggressive in terms of informing the reader
about what these functions are doing.
Fill in the parameter names, such as:
int out_of_line_wait_on_bit_timeout(void *word, int, wait_bit_action_f *action, unsigned int mode, unsigned long timeout);
Also turn spurious (and inconsistently utilized) cases of 'unsigned' into 'unsigned int'.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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So wait-bit-queue head variables are often named:
struct wait_bit_queue *q
... which is a bit ambiguous and super confusing, because
they clearly suggest wait-queue head semantics and behavior
(they rhyme with the old wait_queue_t *q naming), while they
are extended wait-queue _entries_, not heads!
They are misnomers in two ways:
- the 'wait_bit_queue' leaves open the question of whether
it's an entry or a head
- the 'q' parameter and local variable naming falsely implies
that it's a 'queue' - while it's an entry.
This resulted in sometimes confusing cases such as:
finish_wait(wq, &q->wait);
where the 'q' is not a wait-queue head, but a wait-bit-queue entry.
So improve this all by standardizing wait-bit-queue nomenclature
similar to wait-queue head naming:
struct wait_bit_queue => struct wait_bit_queue_entry
q => wbq_entry
Which makes it all a much clearer:
struct wait_bit_queue_entry *wbq_entry
... and turns the former confusing piece of code into:
finish_wait(wq_head, &wbq_entry->wq_entry;
which IMHO makes it apparently clear what we are doing,
without having to analyze the context of the code: we are
adding a wait-queue entry to a regular wait-queue head,
which entry is embedded in a wait-bit-queue entry.
I'm not a big fan of acronyms, but repeating wait_bit_queue_entry
in field and local variable names is too long, so Hopefully it's
clear enough that 'wq_' prefixes stand for wait-queues, while
'wbq_' prefixes stand for wait-bit-queues.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Rename 'struct wait_bit_queue::wait' to ::wq_entry, to more clearly
name it as a wait-queue entry.
Propagate it to a couple of usage sites where the wait-bit-queue internals
are exposed.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The wait-queue head parameters and variables are named in a
couple of ways, we have the following variants currently:
wait_queue_head_t *q
wait_queue_head_t *wq
wait_queue_head_t *head
In particular the 'wq' naming is ambiguous in the sense whether it's
a wait-queue head or entry name - as entries were often named 'wait'.
( Not to mention the confusion of any readers coming over from
workqueue-land. )
Standardize all this around a single, unambiguous parameter and
variable name:
struct wait_queue_head *wq_head
which is easy to grep for and also rhymes nicely with the wait-queue
entry naming:
struct wait_queue_entry *wq_entry
Also rename:
struct __wait_queue_head => struct wait_queue_head
... and use this struct type to migrate from typedefs usage to 'struct'
usage, which is more in line with existing kernel practices.
Don't touch any external users and preserve the main wait_queue_head_t
typedef.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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So the various wait-queue entry variables in include/linux/wait.h
and kernel/sched/wait.c are named in a colorfully inconsistent
way:
wait_queue_entry_t *wait
wait_queue_entry_t *__wait (even in plain C code!)
wait_queue_entry_t *q (!)
wait_queue_entry_t *new (making anyone who knows C++ cringe)
wait_queue_entry_t *old
I think part of the reason for the inconsistency is the constant
apparent confusion about what a wait queue 'head' versus 'entry' is.
( Some of the documentation talks about a 'wait descriptor', which is
the wait-queue entry itself - further adding to the confusion. )
The most common name is 'wait', but that in itself is somewhat
ambiguous as well, as it does not really make it clear whether
it's a wait-queue entry or head.
To improve all this name the wait-queue entry structure parameters
and variables consistently and push through this naming into all
the wait.h and wait.c code:
struct wait_queue_entry *wq_entry
The 'wq_' prefix makes it easy to grep for, and we also use the
opportunity to move away from the typedef to a plain 'struct' naming:
in the kernel we typically reserve typedefs for cases where a
C structure is really small and somewhat opaque - such as pte_t.
wait-queue entries are neither small nor opaque, so use the more
standard 'struct xxx_entry' list management code nomenclature instead.
( We don't touch external users, and we preserve the typedef as well
for actual wait-queue users, to reduce unnecessary churn. )
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Rename:
wait_queue_t => wait_queue_entry_t
'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue",
but in reality it's a queue *entry*. The 'real' queue is the wait queue head,
which had to carry the name.
Start sorting this out by renaming it to 'wait_queue_entry_t'.
This also allows the real structure name 'struct __wait_queue' to
lose its double underscore and become 'struct wait_queue_entry',
which is the more canonical nomenclature for such data types.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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pi_mutex isn't supposed to be tracked by lockdep, but just
passing NULLs for name and key will cause lockdep to spew a
warning and die, which is not what we want it to do.
Skip lockdep initialization if the caller passed NULLs for
name and key, suggesting such initialization isn't desired.
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: f5694788ad8d ("rt_mutex: Add lockdep annotations")
Link: http://lkml.kernel.org/r/20170618140548.4763-1-alexander.levin@verizon.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core
Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:
User visible changes:
- Allow adding and removing fields to the default 'perf script' columns,
using + or - as field prefixes to do so (Andi Kleen)
- Display titles in left frame in the annotate browser (Jin Yao)
- Allow resolving the DSO name with 'perf script -F brstack{sym,off},dso'
(Mark Santaniello)
- Support function filtering in 'perf ftrace' (Namhyung Kim)
- Allow specifying function call depth in 'perf ftrace' (Namhyumg Kim)
Infrastructure changes:
- Adopt __noreturn, __printf, __scanf, noinline, __packed and __aligned
__alignment__(()) markers, to make the tools/ source code base to be
more compact and look more like kernel code (Arnaldo Carvalho de Melo)
- Remove unnecessary check in annotate_browser_write() (Jin Yao)
- Return arch from symbol__disassemble() so that callers, such as
the annotate TUI browser to use arch specific formattings, such
as the upcoming instruction micro-op fusion on Intel Core (Jin Yao)
- Remove superfluous check before use in the coresight code base (Kim
Phillips)
- Remove unused SAMPLE_SIZE defines and BTS priv array (Kim Phillips)
- Error handling fix/tidy ups in 'perf config' (Taeung Song)
- Avoid error in the BPF proggie built with clang in 'perf test llvm'
when PROFILE_ALL_BRANCHES is set (Wang Nan)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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rcu_read_(un)lock(), list_*_rcu(), and synchronize_rcu() are used for a secure
access and manipulation of the list of patches that modify the same function.
In particular, it is the variable func_stack that is accessible from the ftrace
handler via struct ftrace_ops and klp_ops.
Of course, it synchronizes also some states of the patch on the top of the
stack, e.g. func->transition in klp_ftrace_handler.
At the same time, this mechanism guards also the manipulation of
task->patch_state. It is modified according to the state of the transition and
the state of the process.
Now, all this works well as long as RCU works well. Sadly livepatching might
get into some corner cases when this is not true. For example, RCU is not
watching when rcu_read_lock() is taken in idle threads. It is because they
might sleep and prevent reaching the grace period for too long.
There are ways how to make RCU watching even in idle threads, see
rcu_irq_enter(). But there is a small location inside RCU infrastructure when
even this does not work.
This small problematic location can be detected either before calling
rcu_irq_enter() by rcu_irq_enter_disabled() or later by rcu_is_watching().
Sadly, there is no safe way how to handle it. Once we detect that RCU was not
watching, we might see inconsistent state of the function stack and the related
variables in klp_ftrace_handler(). Then we could do a wrong decision, use an
incompatible implementation of the function and break the consistency of the
system. We could warn but we could not avoid the damage.
Fortunately, ftrace has similar problems and they seem to be solved well there.
It uses a heavy weight implementation of some RCU operations. In particular, it
replaces:
+ rcu_read_lock() with preempt_disable_notrace()
+ rcu_read_unlock() with preempt_enable_notrace()
+ synchronize_rcu() with schedule_on_each_cpu(sync_work)
My understanding is that this is RCU implementation from a stone age. It meets
the core RCU requirements but it is rather ineffective. Especially, it does not
allow to batch or speed up the synchronize calls.
On the other hand, it is very trivial. It allows to safely trace and/or
livepatch even the RCU core infrastructure. And the effectiveness is a not a
big issue because using ftrace or livepatches on productive systems is a rare
operation. The safety is much more important than a negligible extra load.
Note that the alternative implementation follows the RCU principles. Therefore,
we could and actually must use list_*_rcu() variants when manipulating the
func_stack. These functions allow to access the pointers in the right
order and with the right barriers. But they do not use any other
information that would be set only by rcu_read_lock().
Also note that there are actually two problems solved in ftrace:
First, it cares about the consistency of RCU read sections. It is being solved
the way as described and used in this patch.
Second, ftrace needs to make sure that nobody is inside the dynamic trampoline
when it is being freed. For this, it also calls synchronize_rcu_tasks() in
preemptive kernel in ftrace_shutdown().
Livepatch has similar problem but it is solved by ftrace for free.
klp_ftrace_handler() is a good guy and never sleeps. In addition, it is
registered with FTRACE_OPS_FL_DYNAMIC. It causes that
unregister_ftrace_function() calls:
* schedule_on_each_cpu(ftrace_sync) - always
* synchronize_rcu_tasks() - in preemptive kernel
The effect is that nobody is neither inside the dynamic trampoline nor inside
the ftrace handler after unregister_ftrace_function() returns.
[jkosina@suse.cz: reformat changelog, fix comment]
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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