linux.git/drivers/usb/gadget/function/f_fs.c, branch v5.8

kernel: set USER_DS in kthread_use_mm

2020-06-11T02:14:18+00:00

Some architectures like arm64 and s390 require USER_DS to be set for
kernel threads to access user address space, which is the whole purpose of
kthread_use_mm, but other like x86 don't.  That has lead to a huge mess
where some callers are fixed up once they are tested on said
architectures, while others linger around and yet other like io_uring try
to do "clever" optimizations for what usually is just a trivial asignment
to a member in the thread_struct for most architectures.

Make kthread_use_mm set USER_DS, and kthread_unuse_mm restore to the
previous value instead.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Tested-by: Jens Axboe 
Reviewed-by: Jens Axboe 
Acked-by: Michael S. Tsirkin 
Cc: Alex Deucher 
Cc: Al Viro 
Cc: Felipe Balbi 
Cc: Felix Kuehling 
Cc: Jason Wang 
Cc: Zhenyu Wang 
Cc: Zhi Wang 
Cc: Greg Kroah-Hartman 
Link: http://lkml.kernel.org/r/20200404094101.672954-7-hch@lst.de
Signed-off-by: Linus Torvalds

kernel: better document the use_mm/unuse_mm API contract

2020-06-11T02:14:18+00:00

Switch the function documentation to kerneldoc comments, and add
WARN_ON_ONCE asserts that the calling thread is a kernel thread and does
not have ->mm set (or has ->mm set in the case of unuse_mm).

Also give the functions a kthread_ prefix to better document the use case.

[hch@lst.de: fix a comment typo, cover the newly merged use_mm/unuse_mm caller in vfio]
  Link: http://lkml.kernel.org/r/20200416053158.586887-3-hch@lst.de
[sfr@canb.auug.org.au: powerpc/vas: fix up for {un}use_mm() rename]
  Link: http://lkml.kernel.org/r/20200422163935.5aa93ba5@canb.auug.org.au

Signed-off-by: Christoph Hellwig 
Signed-off-by: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Tested-by: Jens Axboe 
Reviewed-by: Jens Axboe 
Acked-by: Felix Kuehling 
Acked-by: Greg Kroah-Hartman  [usb]
Acked-by: Haren Myneni 
Cc: Alex Deucher 
Cc: Al Viro 
Cc: Felipe Balbi 
Cc: Jason Wang 
Cc: "Michael S. Tsirkin" 
Cc: Zhenyu Wang 
Cc: Zhi Wang 
Link: http://lkml.kernel.org/r/20200404094101.672954-6-hch@lst.de
Signed-off-by: Linus Torvalds

kernel: move use_mm/unuse_mm to kthread.c

2020-06-11T02:14:18+00:00

Patch series "improve use_mm / unuse_mm", v2.

This series improves the use_mm / unuse_mm interface by better documenting
the assumptions, and my taking the set_fs manipulations spread over the
callers into the core API.

This patch (of 3):

Use the proper API instead.

Link: http://lkml.kernel.org/r/20200404094101.672954-1-hch@lst.de

These helpers are only for use with kernel threads, and I will tie them
more into the kthread infrastructure going forward.  Also move the
prototypes to kthread.h - mmu_context.h was a little weird to start with
as it otherwise contains very low-level MM bits.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Tested-by: Jens Axboe 
Reviewed-by: Jens Axboe 
Acked-by: Felix Kuehling 
Cc: Alex Deucher 
Cc: Al Viro 
Cc: Felipe Balbi 
Cc: Jason Wang 
Cc: "Michael S. Tsirkin" 
Cc: Zhenyu Wang 
Cc: Zhi Wang 
Cc: Greg Kroah-Hartman 
Link: http://lkml.kernel.org/r/20200404094101.672954-1-hch@lst.de
Link: http://lkml.kernel.org/r/20200416053158.586887-1-hch@lst.de
Link: http://lkml.kernel.org/r/20200404094101.672954-5-hch@lst.de
Signed-off-by: Linus Torvalds

usb: gadget: f_fs: remove unneeded semicolon in __ffs_data_got_descs()

2020-05-25T08:09:38+00:00

Fix the following coccicheck warning:

drivers/usb/gadget/function/f_fs.c:2507:2-3: Unneeded semicolon

Reported-by: Hulk Robot 
Signed-off-by: Jason Yan 
Signed-off-by: Felipe Balbi

usb: f_fs: Clear OS Extended descriptor counts to zero in ffs_data_reset()

2020-04-16T12:59:49+00:00

For userspace functions using OS Descriptors, if a function also supplies
Extended Property descriptors currently the counts and lengths stored in
the ms_os_descs_ext_prop_{count,name_len,data_len} variables are not
getting reset to 0 during an unbind or when the epfiles are closed. If
the same function is re-bound and the descriptors are re-written, this
results in those count/length variables to monotonically increase
causing the VLA allocation in _ffs_func_bind() to grow larger and larger
at each bind/unbind cycle and eventually fail to allocate.

Fix this by clearing the ms_os_descs_ext_prop count & lengths to 0 in
ffs_data_reset().

Fixes: f0175ab51993 ("usb: gadget: f_fs: OS descriptors support")
Cc: stable@vger.kernel.org
Signed-off-by: Udipto Goswami 
Signed-off-by: Sriharsha Allenki 
Reviewed-by: Manu Gautam 
Link: https://lore.kernel.org/r/20200402044521.9312-1-sallenki@codeaurora.org
Signed-off-by: Greg Kroah-Hartman

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-03-30T23:17:15+00:00

Pull locking updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Continued user-access cleanups in the futex code.

   - percpu-rwsem rewrite that uses its own waitqueue and atomic_t
     instead of an embedded rwsem. This addresses a couple of
     weaknesses, but the primary motivation was complications on the -rt
     kernel.

   - Introduce raw lock nesting detection on lockdep
     (CONFIG_PROVE_RAW_LOCK_NESTING=y), document the raw_lock vs. normal
     lock differences. This too originates from -rt.

   - Reuse lockdep zapped chain_hlocks entries, to conserve RAM
     footprint on distro-ish kernels running into the "BUG:
     MAX_LOCKDEP_CHAIN_HLOCKS too low!" depletion of the lockdep
     chain-entries pool.

   - Misc cleanups, smaller fixes and enhancements - see the changelog
     for details"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (55 commits)
  fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t
  thermal/x86_pkg_temp: Make pkg_temp_lock a raw_spinlock_t
  Documentation/locking/locktypes: Minor copy editor fixes
  Documentation/locking/locktypes: Further clarifications and wordsmithing
  m68knommu: Remove mm.h include from uaccess_no.h
  x86: get rid of user_atomic_cmpxchg_inatomic()
  generic arch_futex_atomic_op_inuser() doesn't need access_ok()
  x86: don't reload after cmpxchg in unsafe_atomic_op2() loop
  x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end()
  objtool: whitelist __sanitizer_cov_trace_switch()
  [parisc, s390, sparc64] no need for access_ok() in futex handling
  sh: no need of access_ok() in arch_futex_atomic_op_inuser()
  futex: arch_futex_atomic_op_inuser() calling conventions change
  completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all()
  lockdep: Add posixtimer context tracing bits
  lockdep: Annotate irq_work
  lockdep: Add hrtimer context tracing bits
  lockdep: Introduce wait-type checks
  completion: Use simple wait queues
  sched/swait: Prepare usage in completions
  ...

usb: gadget: f_fs: Fix use after free issue as part of queue failure

2020-03-26T14:05:44+00:00

In AIO case, the request is freed up if ep_queue fails.
However, io_data->req still has the reference to this freed
request. In the case of this failure if there is aio_cancel
call on this io_data it will lead to an invalid dequeue
operation and a potential use after free issue.
Fix this by setting the io_data->req to NULL when the request
is freed as part of queue failure.

Fixes: 2e4c7553cd6f ("usb: gadget: f_fs: add aio support")
Signed-off-by: Sriharsha Allenki 
CC: stable 
Reviewed-by: Peter Chen 
Link: https://lore.kernel.org/r/20200326115620.12571-1-sallenki@codeaurora.org
Signed-off-by: Greg Kroah-Hartman

completion: Use simple wait queues

2020-03-21T15:00:24+00:00

completion uses a wait_queue_head_t to enqueue waiters.

wait_queue_head_t contains a spinlock_t to protect the list of waiters
which excludes it from being used in truly atomic context on a PREEMPT_RT
enabled kernel.

The spinlock in the wait queue head cannot be replaced by a raw_spinlock
because:

  - wait queues can have custom wakeup callbacks, which acquire other
    spinlock_t locks and have potentially long execution times

  - wake_up() walks an unbounded number of list entries during the wake up
    and may wake an unbounded number of waiters.

For simplicity and performance reasons complete() should be usable on
PREEMPT_RT enabled kernels.

completions do not use custom wakeup callbacks and are usually single
waiter, except for a few corner cases.

Replace the wait queue in the completion with a simple wait queue (swait),
which uses a raw_spinlock_t for protecting the waiter list and therefore is
safe to use inside truly atomic regions on PREEMPT_RT.

There is no semantical or functional change:

  - completions use the exclusive wait mode which is what swait provides

  - complete() wakes one exclusive waiter

  - complete_all() wakes all waiters while holding the lock which protects
    the wait queue against newly incoming waiters. The conversion to swait
    preserves this behaviour.

complete_all() might cause unbound latencies with a large number of waiters
being woken at once, but most complete_all() usage sites are either in
testing or initialization code or have only a really small number of
concurrent waiters which for now does not cause a latency problem. Keep it
simple for now.

The fixup of the warning check in the USB gadget driver is just a straight
forward conversion of the lockless waiter check from one waitqueue type to
the other.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Davidlohr Bueso 
Reviewed-by: Joel Fernandes (Google) 
Acked-by: Linus Torvalds 
Link: https://lkml.kernel.org/r/20200321113242.317954042@linutronix.de

usb: gadget: ffs: ffs_aio_cancel(): Save/restore IRQ flags

2020-02-11T06:45:45+00:00

ffs_aio_cancel() can be called from both interrupt and thread context. Make
sure that the current IRQ state is saved and restored by using
spin_{un,}lock_irq{save,restore}().

Otherwise undefined behavior might occur.

Acked-by: Michal Nazarewicz 
Signed-off-by: Lars-Peter Clausen 
Signed-off-by: Alexandru Ardelean 
Signed-off-by: Felipe Balbi

Merge branch 'merge.nfs-fs_parse.1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2020-02-08T21:26:41+00:00

Pull vfs file system parameter updates from Al Viro:
 "Saner fs_parser.c guts and data structures. The system-wide registry
  of syntax types (string/enum/int32/oct32/.../etc.) is gone and so is
  the horror switch() in fs_parse() that would have to grow another case
  every time something got added to that system-wide registry.

  New syntax types can be added by filesystems easily now, and their
  namespace is that of functions - not of system-wide enum members. IOW,
  they can be shared or kept private and if some turn out to be widely
  useful, we can make them common library helpers, etc., without having
  to do anything whatsoever to fs_parse() itself.

  And we already get that kind of requests - the thing that finally
  pushed me into doing that was "oh, and let's add one for timeouts -
  things like 15s or 2h". If some filesystem really wants that, let them
  do it. Without somebody having to play gatekeeper for the variants
  blessed by direct support in fs_parse(), TYVM.

  Quite a bit of boilerplate is gone. And IMO the data structures make a
  lot more sense now. -200LoC, while we are at it"

* 'merge.nfs-fs_parse.1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (25 commits)
  tmpfs: switch to use of invalfc()
  cgroup1: switch to use of errorfc() et.al.
  procfs: switch to use of invalfc()
  hugetlbfs: switch to use of invalfc()
  cramfs: switch to use of errofc() et.al.
  gfs2: switch to use of errorfc() et.al.
  fuse: switch to use errorfc() et.al.
  ceph: use errorfc() and friends instead of spelling the prefix out
  prefix-handling analogues of errorf() and friends
  turn fs_param_is_... into functions
  fs_parse: handle optional arguments sanely
  fs_parse: fold fs_parameter_desc/fs_parameter_spec
  fs_parser: remove fs_parameter_description name field
  add prefix to fs_context->log
  ceph_parse_param(), ceph_parse_mon_ips(): switch to passing fc_log
  new primitive: __fs_parse()
  switch rbd and libceph to p_log-based primitives
  struct p_log, variants of warnf() et.al. taking that one instead
  teach logfc() to handle prefices, give it saner calling conventions
  get rid of cg_invalf()
  ...