Currently, blk-mq timeout path synchronizes against the usual
issue/completion path using a complex scheme involving atomic
bitflags, REQ_ATOM_*, memory barriers and subtle memory coherence
rules.  Unfortunately, it contains quite a few holes.

There's a complex dancing around REQ_ATOM_STARTED and
REQ_ATOM_COMPLETE between issue/completion and timeout paths; however,
they don't have a synchronization point across request recycle
instances and it isn't clear what the barriers add.
blk_mq_check_expired() can easily read STARTED from N-2'th iteration,
deadline from N-1'th, blk_mark_rq_complete() against Nth instance.

In fact, it's pretty easy to make blk_mq_check_expired() terminate a
later instance of a request.  If we induce 5 sec delay before
time_after_eq() test in blk_mq_check_expired(), shorten the timeout to
2s, and issue back-to-back large IOs, blk-mq starts timing out
requests spuriously pretty quickly.  Nothing actually timed out.  It
just made the call on a recycle instance of a request and then
terminated a later instance long after the original instance finished.
The scenario isn't theoretical either.

This patch replaces the broken synchronization mechanism with a RCU
and generation number based one.

1. Each request has a u64 generation + state value, which can be
   updated only by the request owner.  Whenever a request becomes
   in-flight, the generation number gets bumped up too.  This provides
   the basis for the timeout path to distinguish different recycle
   instances of the request.

   Also, marking a request in-flight and setting its deadline are
   protected with a seqcount so that the timeout path can fetch both
   values coherently.

2. The timeout path fetches the generation, state and deadline.  If
   the verdict is timeout, it records the generation into a dedicated
   request abortion field and does RCU wait.

3. The completion path is also protected by RCU (from the previous
   patch) and checks whether the current generation number and state
   match the abortion field.  If so, it skips completion.

4. The timeout path, after RCU wait, scans requests again and
   terminates the ones whose generation and state still match the ones
   requested for abortion.

   By now, the timeout path knows that either the generation number
   and state changed if it lost the race or the completion will yield
   to it and can safely timeout the request.

While it's more lines of code, it's conceptually simpler, doesn't
depend on direct use of subtle memory ordering or coherence, and
hopefully doesn't terminate the wrong instance.

While this change makes REQ_ATOM_COMPLETE synchronization unnecessary
between issue/complete and timeout paths, REQ_ATOM_COMPLETE isn't
removed yet as it's still used in other places.  Future patches will
move all state tracking to the new mechanism and remove all bitops in
the hot paths.

Note that this patch adds a comment explaining a race condition in
BLK_EH_RESET_TIMER path.  The race has always been there and this
patch doesn't change it.  It's just documenting the existing race.

v2: - Fixed BLK_EH_RESET_TIMER handling as pointed out by Jianchao.
    - s/request->gstate_seqc/request->gstate_seq/ as suggested by Peter.
    - READ_ONCE() added in blk_mq_rq_update_state() as suggested by Peter.

v3: - Fixed possible extended seqcount / u64_stats_sync read looping
      spotted by Peter.
    - MQ_RQ_IDLE was incorrectly being set in complete_request instead
      of free_request.  Fixed.

v4: - Rebased on top of hctx_lock() refactoring patch.
    - Added comment explaining the use of hctx_lock() in completion path.

v5: - Added comments requested by Bart.
    - Note the addition of BLK_EH_RESET_TIMER race condition in the
      commit message.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Many kernel drivers contain code that allocates and frees both a
scatterlist and the pages that populate that scatterlist.
Introduce functions in lib/scatterlist.c that perform these tasks
instead of duplicating this functionality in multiple drivers.
Only include these functions in the build if CONFIG_SGL_ALLOC=y
to avoid that the kernel size increases if this functionality is
not used.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

bcache is the only user of bio_alloc_pages(), so move this function into
bcache, and avoid it being misused in the future.

Also rename it to bch_bio_allo_pages() since it is bcache only.
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Firstly this patch introduces BVEC_ITER_ALL_INIT for iterating one bio
from start to end.

As we need to support multipage bvecs, don't access bio->bi_io_vec
in copy_to_high_bio_irq(), and just use the standard iterator for that.
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The following helpers are introduced for converting current users of
direct access to bvec table, and prepares for supporting multipage bvec:

	bio_pages_all()
	bio_first_bvec_all()
	bio_first_page_all()
	bio_last_bvec_all()

All are named as bio_*_all() to following bio_for_each_segment_all(),
they can only be used on bio of !bio_flagged(bio, BIO_CLONED), that means
the whole bvec table is covered.
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Components relying only on the request_queue structure for accessing
block devices (e.g. I/O schedulers) have a limited knowledged of the
device characteristics. In particular, the device capacity cannot be
easily discovered, which for a zoned block device also result in the
inability to easily know the number of zones of the device (the zone
size is indicated by the chunk_sectors field of the queue limits).

Introduce the nr_zones field to the request_queue structure to simplify
access to this information. Also, add the bitmap seq_zone_bitmap which
indicates which zones of the device are sequential zones (write
preferred or write required) and the bitmap seq_zones_wlock which
indicates if a zone is write locked, that is, if a write request
targeting a zone was dispatched to the device. These fields are
initialized by the low level block device driver (sd.c for ZBC/ZAC
disks). They are not initialized by stacking drivers (device mappers)
handling zoned block devices (e.g. dm-linear).

Using this, I/O schedulers can introduce zone write locking to control
request dispatching to a zoned block device and avoid write request
reordering by limiting to at most a single write request per zone
outside of the scheduler at any time.

Based on previous patches from Damien Le Moal.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
[Damien]
* Fixed comments and identation in blkdev.h
* Changed helper functions
* Fixed this commit message
Signed-off-by: NDamien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Allow to set the over-provision percentage on target creation. In case
that the value is not provided, fall back to the default value set by
the target.

In pblk, set the default OP to 11% of the total size of the device
Signed-off-by: NJavier González <javier@cnexlabs.com>
Signed-off-by: NHans Holmberg <hans.holmberg@cnexlabs.com>
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Prepare for the 2.0 revision by adapting the geometry
structures to coexist with the 1.2 revision.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Reviewed-by: NJavier González <javier@cnexlabs.com>
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The lower page table is unused. All page tables reported by 1.2
devices are all reporting a sequential 1:1 page mapping. This is
also not used going forward with the 2.0 revision.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Reviewed-by: NJavier González <javier@cnexlabs.com>
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Remove the wait filed in nvm_rq. It is not used anymore, as targets rely
on the functionality provided by the LightNVM subsystem when sending
sync I/O.
Signed-off-by: NJavier González <javier@cnexlabs.com>
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Now that rrpc have been removed. Also remove the hybrid 1.2 support
from the core.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Now that rrpc has been removed, the only users of the ppa helpers
is pblk. However, pblk already defines similar functions.

Switch pblk to use the internal ones, and remove the generic ppa
helpers.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

[ Note, this is a Git cherry-pick of the following commit:

    506458ef ("locking/barriers: Convert users of lockless_dereference() to READ_ONCE()")

  ... for easier x86 PTI code testing and back-porting. ]

READ_ONCE() now has an implicit smp_read_barrier_depends() call, so it
can be used instead of lockless_dereference() without any change in
semantics.
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-4-git-send-email-will.deacon@arm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

[ Note, this is a Git cherry-pick of the following commit:

    76ebbe78 ("locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE()")

  ... for easier x86 PTI code testing and back-porting. ]

In preparation for the removal of lockless_dereference(), which is the
same as READ_ONCE() on all architectures other than Alpha, add an
implicit smp_read_barrier_depends() to READ_ONCE() so that it can be
used to head dependency chains on all architectures.
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-3-git-send-email-will.deacon@arm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

We'd like to use the 'PTI' acronym for 'Page Table Isolation' - free up the
namespace by renaming the <linux/pti.h> driver header to <linux/intel-pti.h>.

(Also standardize the header guard name while at it.)

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: J Freyensee <james_p_freyensee@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Following the previous patch, RED is now using the new uniform uapi
for indicating it's offloaded. As a result, TC_RED_OFFLOADED is no
longer utilized by kernel and can be removed [as it's still not
part of any stable release].

Fixes: 602f3baf ("net_sch: red: Add offload ability to RED qdisc")
Signed-off-by: NYuval Mintz <yuvalm@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Qdiscs can be offloaded to HW, but current implementation isn't uniform.
Instead, qdiscs either pass information about offload status via their
TCA_OPTIONS or omit it altogether.

Introduce a new attribute - TCA_HW_OFFLOAD that would form a uniform
uAPI for the offloading status of qdiscs.
Signed-off-by: NYuval Mintz <yuvalm@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

David Rientjes has reported the following memory corruption while the
oom reaper tries to unmap the victims address space

  BUG: Bad page map in process oom_reaper  pte:6353826300000000 pmd:00000000
  addr:00007f50cab1d000 vm_flags:08100073 anon_vma:ffff9eea335603f0 mapping:          (null) index:7f50cab1d
  file:          (null) fault:          (null) mmap:          (null) readpage:          (null)
  CPU: 2 PID: 1001 Comm: oom_reaper
  Call Trace:
     unmap_page_range+0x1068/0x1130
     __oom_reap_task_mm+0xd5/0x16b
     oom_reaper+0xff/0x14c
     kthread+0xc1/0xe0

Tetsuo Handa has noticed that the synchronization inside exit_mmap is
insufficient.  We only synchronize with the oom reaper if
tsk_is_oom_victim which is not true if the final __mmput is called from
a different context than the oom victim exit path.  This can trivially
happen from context of any task which has grabbed mm reference (e.g.  to
read /proc/<pid>/ file which requires mm etc.).

The race would look like this

  oom_reaper		oom_victim		task
						mmget_not_zero
			do_exit
			  mmput
  __oom_reap_task_mm				mmput
  						  __mmput
						    exit_mmap
						      remove_vma
    unmap_page_range

Fix this issue by providing a new mm_is_oom_victim() helper which
operates on the mm struct rather than a task.  Any context which
operates on a remote mm struct should use this helper in place of
tsk_is_oom_victim.  The flag is set in mark_oom_victim and never cleared
so it is stable in the exit_mmap path.

Debugged by Tetsuo Handa.

Link: http://lkml.kernel.org/r/20171210095130.17110-1-mhocko@kernel.org
Fixes: 21292580 ("mm: oom: let oom_reap_task and exit_mmap run concurrently")
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Reported-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Andrea Argangeli <andrea@kernel.org>
Cc: <stable@vger.kernel.org>	[4.14]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In testing, we found that nfsd threads may call set_groups in parallel
for the same entry cached in auth.unix.gid, racing in the call of
groups_sort, corrupting the groups for that entry and leading to
permission denials for the client.

This patch:
 - Make groups_sort globally visible.
 - Move the call to groups_sort to the modifiers of group_info
 - Remove the call to groups_sort from set_groups

Link: http://lkml.kernel.org/r/20171211151420.18655-1-thiago.becker@gmail.comSigned-off-by: NThiago Rafael Becker <thiago.becker@gmail.com>
Reviewed-by: NMatthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: NNeilBrown <neilb@suse.com>
Acked-by: N"J. Bruce Fields" <bfields@fieldses.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

gcc-8 warns about using strncpy() with the source size as the limit:

  fs/exec.c:1223:32: error: argument to 'sizeof' in 'strncpy' call is the same expression as the source; did you mean to use the size of the destination? [-Werror=sizeof-pointer-memaccess]

This is indeed slightly suspicious, as it protects us from source
arguments without NUL-termination, but does not guarantee that the
destination is terminated.

This keeps the strncpy() to ensure we have properly padded target
buffer, but ensures that we use the correct length, by passing the
actual length of the destination buffer as well as adding a build-time
check to ensure it is exactly TASK_COMM_LEN.

There are only 23 callsites which I all reviewed to ensure this is
currently the case.  We could get away with doing only the check or
passing the right length, but it doesn't hurt to do both.

Link: http://lkml.kernel.org/r/20171205151724.1764896-1-arnd@arndb.deSigned-off-by: NArnd Bergmann <arnd@arndb.de>
Suggested-by: NKees Cook <keescook@chromium.org>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NIngo Molnar <mingo@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Aleksa Sarai <asarai@suse.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The hardened strlen() function causes rather large stack usage in at
least one file in the kernel, in particular when CONFIG_KASAN is
enabled:

  drivers/media/usb/em28xx/em28xx-dvb.c: In function 'em28xx_dvb_init':
  drivers/media/usb/em28xx/em28xx-dvb.c:2062:1: error: the frame size of 3256 bytes is larger than 204 bytes [-Werror=frame-larger-than=]

Analyzing this problem led to the discovery that gcc fails to merge the
stack slots for the i2c_board_info[] structures after we strlcpy() into
them, due to the 'noreturn' attribute on the source string length check.

I reported this as a gcc bug, but it is unlikely to get fixed for gcc-8,
since it is relatively easy to work around, and it gets triggered
rarely.  An earlier workaround I did added an empty inline assembly
statement before the call to fortify_panic(), which works surprisingly
well, but is really ugly and unintuitive.

This is a new approach to the same problem, this time addressing it by
not calling the 'extern __real_strnlen()' function for string constants
where __builtin_strlen() is a compile-time constant and therefore known
to be safe.

We do this by checking if the last character in the string is a
compile-time constant '\0'.  If it is, we can assume that strlen() of
the string is also constant.

As a side-effect, this should also improve the object code output for
any other call of strlen() on a string constant.

[akpm@linux-foundation.org: add comment]
Link: http://lkml.kernel.org/r/20171205215143.3085755-1-arnd@arndb.de
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
Link: https://patchwork.kernel.org/patch/9980413/
Link: https://patchwork.kernel.org/patch/9974047/
Fixes: 6974f0c4 ("include/linux/string.h: add the option of fortified string.h functions")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Martin Wilck <mwilck@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a variant of rbtree_replace_node() that maintains the leftmost cache
of struct rbtree_root_cached when replacing nodes within the rbtree.

As drm_mm is the only rb_replace_node() being used on an interval tree,
the mistake looks fairly self-contained.  Furthermore the only user of
drm_mm_replace_node() is its testsuite...

Testcase: igt/drm_mm/replace

Link: http://lkml.kernel.org/r/20171122100729.3742-1-chris@chris-wilson.co.uk
Link: https://patchwork.freedesktop.org/patch/msgid/20171109212435.9265-1-chris@chris-wilson.co.uk
Fixes: f808c13f ("lib/interval_tree: fast overlap detection")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: NDavidlohr Bueso <dbueso@suse.de>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The <linux/bug.h> was removed from radix-tree.h by commit f5bba9d1
("include/linux/radix-tree.h: remove unneeded #include <linux/bug.h>").

Since that commit, tools/testing/radix-tree/ couldn't pass compilation
due to tools/testing/radix-tree/idr.c:17: undefined reference to
WARN_ON_ONCE.  This patch adds the bug.h header to idr.h to solve the
issue.

Link: http://lkml.kernel.org/r/1511963726-34070-2-git-send-email-wei.w.wang@intel.com
Fixes: f5bba9d1 ("include/linux/radix-tree.h: remove unneeded #include <linux/bug.h>")
Signed-off-by: NWei Wang <wei.w.wang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

PROBE_DEFER also uses system_wq to reprobe drivers, which means when
that again fails, and we try to flush the overall system_wq (to get
all the delayed connectore cleanup work_struct completed), we
deadlock.

Fix this by using just a single cleanup work, so that we can only
flush that one and don't block on anything else. That means a free
list plus locking, a standard pattern.

v2:
- Correctly free connectors only on last ref. Oops (Chris).
- use llist_head/node (Chris).

v3
- Add init_llist_head (Chris).

Fixes: a703c550 ("drm: safely free connectors from connector_iter")
Fixes: 613051da ("drm: locking&new iterators for connector_list")
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: <stable@vger.kernel.org> # v4.11+: 613051da ("drm: locking&new iterators for connector_list"
Cc: <stable@vger.kernel.org> # v4.11+
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Javier Martinez Canillas <javier@dowhile0.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Guillaume Tucker <guillaume.tucker@collabora.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Matt Hart <matthew.hart@linaro.org>
Cc: Thierry Escande <thierry.escande@collabora.co.uk>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Tested-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171213124936.17914-1-daniel.vetter@ffwll.ch

IPv4 stack reacts to changes to small MTU, by disabling itself under
RTNL.

But there is a window where threads not using RTNL can see a wrong
device mtu. This can lead to surprises, in igmp code where it is
assumed the mtu is suitable.

Fix this by reading device mtu once and checking IPv4 minimal MTU.

This patch adds missing IPV4_MIN_MTU define, to not abuse
ETH_MIN_MTU anymore.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There are a set of values in the drm_display_info structure for each
connector which hold information derived from EDID. These are computed
in drm_add_display_info. Before this patch, that was only called in
drm_add_edid_modes. This meant that they were only set when EDID was
present and never reset when EDID was not, as happened when the
display was disconnected.

One of these fields, non_desktop, is used from
drm_mode_connector_update_edid_property, the function responsible for
assigning the new edid value to the application-visible property.

Various drivers call these two functions (drm_add_edid_modes and
drm_mode_connector_update_edid_property) in different orders. This
means that even when EDID is present, the drm_display_info fields may
not have been computed at the time that
drm_mode_connector_update_edid_property used the non_desktop value to
set the non_desktop property.

I've added a public function (drm_reset_display_info) that resets the
drm_display_info field values to default values and then made the
drm_add_display_info function public. These two functions are now
called directly from drm_mode_connector_update_edid_property so that
the drm_display_info fields are always computed from the current EDID
information before being used in that function.

This means that the drm_display_info values are often computed twice,
once when the EDID property it set and a second time when EDID is used
to compute modes for the device. The alternative would be to uniformly
ensure that the values were computed once before being used, which
would require that all drivers reliably invoke the two paths in the
same order. The computation is inexpensive enough that it seems more
maintainable in the long term to simply compute them in both paths.

The API to drm_add_display_info has been changed so that it no longer
takes the set of edid-based quirks as a parameter. Rather, it now
computes those quirks itself and returns them for further use by
drm_add_edid_modes.

This patch also includes a number of 'const' additions caused by
drm_mode_connector_update_edid_property taking a 'const struct edid *'
parameter and wanting to pass that along to drm_add_display_info.

v2: after review by Daniel Vetter <daniel.vetter@ffwll.ch>

	Removed EXPORT_SYMBOL_GPL for drm_reset_display_info and
	drm_add_display_info.

	Added FIXME in drm_mode_connector_update_edid_property about
	potentially merging that with drm_add_edid_modes to avoid
	the need for two driver calls.
Signed-off-by: NKeith Packard <keithp@keithp.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20171213084427.31199-1-keithp@keithp.com
(danvet: cherry picked from commit 12a889bf4bca ("drm: rework delayed
connector cleanup in connector_iter") from drm-misc-next since
functional conflict with changes in -next and we need to make sure
both have the right version and nothing gets lost.)
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

There are no longer any kernelspace uses of ACCESS_ONCE(), so we can
remove the definition from <linux/compiler.h>.

This patch removes the ACCESS_ONCE() definition, and updates comments
which referred to it. At the same time, some inconsistent and redundant
whitespace is removed from comments.
Tested-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: apw@canonical.com
Link: http://lkml.kernel.org/r/20171127103824.36526-4-mark.rutland@arm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

This code (CONFIG_LOCKDEP_CROSSRELEASE=y and CONFIG_LOCKDEP_COMPLETIONS=y),
while it found a number of old bugs initially, was also causing too many
false positives that caused people to disable lockdep - which is arguably
a worse overall outcome.

If we disable cross-release by default but keep the code upstream then
in practice the most likely outcome is that we'll allow the situation
to degrade gradually, by allowing entropy to introduce more and more
false positives, until it overwhelms maintenance capacity.

Another bad side effect was that people were trying to work around
the false positives by uglifying/complicating unrelated code. There's
a marked difference between annotating locking operations and
uglifying good code just due to bad lock debugging code ...

This gradual decrease in quality happened to a number of debugging
facilities in the kernel, and lockdep is pretty complex already,
so we cannot risk this outcome.

Either cross-release checking can be done right with no false positives,
or it should not be included in the upstream kernel.

( Note that it might make sense to maintain it out of tree and go through
  the false positives every now and then and see whether new bugs were
  introduced. )

Cc: Byungchul Park <byungchul.park@lge.com>
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: NIngo Molnar <mingo@kernel.org>

When CONFIG_GENERIC_LOCKBEAK=y, locking structures grow an extra int ->break_lock
field which is used to implement raw_spin_is_contended() by setting the field
to 1 when waiting on a lock and clearing it to zero when holding a lock.
However, there are a few problems with this approach:

  - There is a write-write race between a CPU successfully taking the lock
    (and subsequently writing break_lock = 0) and a waiter waiting on
    the lock (and subsequently writing break_lock = 1). This could result
    in a contended lock being reported as uncontended and vice-versa.

  - On machines with store buffers, nothing guarantees that the writes
    to break_lock are visible to other CPUs at any particular time.

  - READ_ONCE/WRITE_ONCE are not used, so the field is potentially
    susceptible to harmful compiler optimisations,

Consequently, the usefulness of this field is unclear and we'd be better off
removing it and allowing architectures to implement raw_spin_is_contended() by
providing a definition of arch_spin_is_contended(), as they can when
CONFIG_GENERIC_LOCKBREAK=n.
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1511894539-7988-3-git-send-email-will.deacon@arm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

guehdr struct is used to build or parse gue packets, which
are always in big endian. It's better to define all guehdr
members as __beXX types.

Also, in validate_gue_flags it's not good to use a __be32
variable for both Standard flags(__be16) and Private flags
(__be32), and pass it to other funcions.

This patch could fix a bunch of sparse warnings from fou.

Fixes: 5024c33a ("gue: Add infrastructure for flags and options")
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Users of ptr_ring expect that it's safe to give the
data structure a pointer and have it be available
to consumers, but that actually requires an smb_wmb
or a stronger barrier.

In absence of such barriers and on architectures that reorder writes,
consumer might read an un=initialized value from an skb pointer stored
in the skb array.  This was observed causing crashes.

To fix, add memory barriers.  The barrier we use is a wmb, the
assumption being that producers do not need to read the value so we do
not need to order these reads.
Reported-by: NGeorge Cherian <george.cherian@cavium.com>
Suggested-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Middle-layer code doing suspend-time optimizations for devices with
the DPM_FLAG_SMART_SUSPEND flag set (currently, the PCI bus type and
the ACPI PM domain) needs to make the core skip ->thaw_early and
->thaw callbacks for those devices in some cases and it sets the
power.direct_complete flag for them for this purpose.

However, it turns out that setting power.direct_complete outside of
the PM core is a bad idea as it triggers an excess invocation of
pm_runtime_enable() in device_resume().

For this reason, provide a helper to clear power.is_late_suspended
and power.is_suspended to be invoked by the middle-layer code in
question instead of setting power.direct_complete and make that code
call the new helper.

Fixes: c4b65157 (PCI / PM: Take SMART_SUSPEND driver flag into account)
Fixes: 05087360 (ACPI / PM: Take SMART_SUSPEND driver flag into account)
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>

Commit 4675ff05 ("kmemcheck: rip it out") has removed the code but
for some reason SPDX header stayed in place.  This looks like a rebase
mistake in the mmotm tree or the merge mistake.  Let's drop those
leftovers as well.
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Mark tcp_sock during a SACK reneging event and invalidate rate samples
while marked. Such rate samples may overestimate bw by including packets
that were SACKed before reneging.

< ack 6001 win 10000 sack 7001:38001
< ack 7001 win 0 sack 8001:38001 // Reneg detected
> seq 7001:8001 // RTO, SACK cleared.
< ack 38001 win 10000

In above example the rate sample taken after the last ack will count
7001-38001 as delivered while the actual delivery rate likely could
be much lower i.e. 7001-8001.

This patch adds a new field tcp_sock.sack_reneg and marks it when we
declare SACK reneging and entering TCP_CA_Loss, and unmarks it after
the last rate sample was taken before moving back to TCP_CA_Open. This
patch also invalidates rate samples taken while tcp_sock.is_sack_reneg
is set.

Fixes: b9f64820 ("tcp: track data delivery rate for a TCP connection")
Signed-off-by: NYousuk Seung <ysseung@google.com>
Signed-off-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Acked-by: NPriyaranjan Jha <priyarjha@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The qmi_wwan minidriver support a 'raw-ip' mode where frames are
received without any ethernet header. This causes alignment issues
because the skbs allocated by usbnet are "IP aligned".

Fix by allowing minidrivers to disable the additional alignment
offset. This is implemented using a per-device flag, since the same
minidriver also supports 'ethernet' mode.

Fixes: 32f7adf6 ("net: qmi_wwan: support "raw IP" mode")
Reported-and-tested-by: NJay Foster <jay@systech.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The coretemp driver build fails when CONFIG_PCI is not enabled because it
uses a function that does not have a stub for that config case, so add the
function stub.

  ../drivers/hwmon/coretemp.c: In function 'adjust_tjmax':
  ../drivers/hwmon/coretemp.c:250:9: error: implicit declaration of function 'pci_get_domain_bus_and_slot' [-Werror=implicit-function-declaration]
    struct pci_dev *host_bridge = pci_get_domain_bus_and_slot(0, 0, devfn);
  ../drivers/hwmon/coretemp.c:250:32: warning: initialization makes pointer from integer without a cast [enabled by default]
    struct pci_dev *host_bridge = pci_get_domain_bus_and_slot(0, 0, devfn);
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
[bhelgaas: identical patch also by Arnd Bergmann <arnd@arndb.de>]
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NGuenter Roeck <linux@roeck-us.net>

Thanks to the scripts/leaking_addresses.pl script, it was found that
some EFI values should not be readable by non-root users.

So make them root-only, and to do that, add a __ATTR_RO_MODE() macro to
make this easier, and use it in other places at the same time.
Reported-by: NLinus Torvalds <torvalds@linux-foundation.org>
Tested-by: NDave Young <dyoung@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Cc: stable <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20171206095010.24170-2-ard.biesheuvel@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

In

commit 613051da
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Dec 14 00:08:06 2016 +0100

    drm: locking&new iterators for connector_list

we've went to extreme lengths to make sure connector iterations works
in any context, without introducing any additional locking context.
This worked, except for a small fumble in the implementation:

When we actually race with a concurrent connector unplug event, and
our temporary connector reference turns out to be the final one, then
everything breaks: We call the connector release function from
whatever context we happen to be in, which can be an irq/atomic
context. And connector freeing grabs all kinds of locks and stuff.

Fix this by creating a specially safe put function for connetor_iter,
which (in this rare case) punts the cleanup to a worker.
Reported-by: NBen Widawsky <ben@bwidawsk.net>
Cc: Ben Widawsky <ben@bwidawsk.net>
Fixes: 613051da ("drm: locking&new iterators for connector_list")
Cc: Dave Airlie <airlied@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: <stable@vger.kernel.org> # v4.11+
Reviewed-by: NDave Airlie <airlied@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171204204818.24745-1-daniel.vetter@ffwll.ch

Old kernels did not check for zero in the irq_state.flags field and old
QEMUs did not zero the flag/reserved fields when calling
KVM_S390_*_IRQ_STATE.  Let's add comments to prevent future uses of
these fields.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Reviewed-by: NCornelia Huck <cohuck@redhat.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Alexander Potapenko reported use of uninitialized memory [1]

This happens when inserting a request socket into TCP ehash,
in __sk_nulls_add_node_rcu(), since sk_reuseport is not initialized.

Bug was added by commit d894ba18 ("soreuseport: fix ordering for
mixed v4/v6 sockets")

Note that d296ba60 ("soreuseport: Resolve merge conflict for v4/v6
ordering fix") missed the opportunity to get rid of
hlist_nulls_add_tail_rcu() :

Both UDP sockets and TCP/DCCP listeners no longer use
__sk_nulls_add_node_rcu() for their hash insertion.

Since all other sockets have unique 4-tuple, the reuseport status
has no special meaning, so we can always use hlist_nulls_add_head_rcu()
for them and save few cycles/instructions.

[1]

==================================================================
BUG: KMSAN: use of uninitialized memory in inet_ehash_insert+0xd40/0x1050
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.13.0+ #3288
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:16
 dump_stack+0x185/0x1d0 lib/dump_stack.c:52
 kmsan_report+0x13f/0x1c0 mm/kmsan/kmsan.c:1016
 __msan_warning_32+0x69/0xb0 mm/kmsan/kmsan_instr.c:766
 __sk_nulls_add_node_rcu ./include/net/sock.h:684
 inet_ehash_insert+0xd40/0x1050 net/ipv4/inet_hashtables.c:413
 reqsk_queue_hash_req net/ipv4/inet_connection_sock.c:754
 inet_csk_reqsk_queue_hash_add+0x1cc/0x300 net/ipv4/inet_connection_sock.c:765
 tcp_conn_request+0x31e7/0x36f0 net/ipv4/tcp_input.c:6414
 tcp_v4_conn_request+0x16d/0x220 net/ipv4/tcp_ipv4.c:1314
 tcp_rcv_state_process+0x42a/0x7210 net/ipv4/tcp_input.c:5917
 tcp_v4_do_rcv+0xa6a/0xcd0 net/ipv4/tcp_ipv4.c:1483
 tcp_v4_rcv+0x3de0/0x4ab0 net/ipv4/tcp_ipv4.c:1763
 ip_local_deliver_finish+0x6bb/0xcb0 net/ipv4/ip_input.c:216
 NF_HOOK ./include/linux/netfilter.h:248
 ip_local_deliver+0x3fa/0x480 net/ipv4/ip_input.c:257
 dst_input ./include/net/dst.h:477
 ip_rcv_finish+0x6fb/0x1540 net/ipv4/ip_input.c:397
 NF_HOOK ./include/linux/netfilter.h:248
 ip_rcv+0x10f6/0x15c0 net/ipv4/ip_input.c:488
 __netif_receive_skb_core+0x36f6/0x3f60 net/core/dev.c:4298
 __netif_receive_skb net/core/dev.c:4336
 netif_receive_skb_internal+0x63c/0x19c0 net/core/dev.c:4497
 napi_skb_finish net/core/dev.c:4858
 napi_gro_receive+0x629/0xa50 net/core/dev.c:4889
 e1000_receive_skb drivers/net/ethernet/intel/e1000/e1000_main.c:4018
 e1000_clean_rx_irq+0x1492/0x1d30
drivers/net/ethernet/intel/e1000/e1000_main.c:4474
 e1000_clean+0x43aa/0x5970 drivers/net/ethernet/intel/e1000/e1000_main.c:3819
 napi_poll net/core/dev.c:5500
 net_rx_action+0x73c/0x1820 net/core/dev.c:5566
 __do_softirq+0x4b4/0x8dd kernel/softirq.c:284
 invoke_softirq kernel/softirq.c:364
 irq_exit+0x203/0x240 kernel/softirq.c:405
 exiting_irq+0xe/0x10 ./arch/x86/include/asm/apic.h:638
 do_IRQ+0x15e/0x1a0 arch/x86/kernel/irq.c:263
 common_interrupt+0x86/0x86

Fixes: d894ba18 ("soreuseport: fix ordering for mixed v4/v6 sockets")
Fixes: d296ba60 ("soreuseport: Resolve merge conflict for v4/v6 ordering fix")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NAlexander Potapenko <glider@google.com>
Acked-by: NCraig Gallek <kraig@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>