1. 12 10月, 2016 24 次提交
    • J
      cfg80211: let ieee80211_amsdu_to_8023s() take only header-less SKB · 7f6990c8
      Johannes Berg 提交于
      There's only a single case where has_80211_header is passed as true,
      which is in mac80211. Given that there's only simple code that needs
      to be done before calling it, export that function from cfg80211
      instead and let mac80211 call it itself.
      Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
      7f6990c8
    • M
      mm: split gfp_mask and mapping flags into separate fields · 9c5d760b
      Michal Hocko 提交于
      mapping->flags currently encodes two different things into a single flag.
      It contains sticky gfp_mask for page cache allocations and AS_ codes used
      to report errors/enospace and other states which are mapping specific.
      Condensing the two semantically unrelated things saves few bytes but it
      also complicates other things.  For one thing the gfp flags space is
      reduced and in fact we are already running out of available bits.  It can
      be assumed that more gfp flags will be necessary later on.
      
      To not introduce the address_space grow (at least on x86_64) we can stick
      it right after private_lock because we have a hole there.
      
      struct address_space {
              struct inode *             host;                 /*     0     8 */
              struct radix_tree_root     page_tree;            /*     8    16 */
              spinlock_t                 tree_lock;            /*    24     4 */
              atomic_t                   i_mmap_writable;      /*    28     4 */
              struct rb_root             i_mmap;               /*    32     8 */
              struct rw_semaphore        i_mmap_rwsem;         /*    40    40 */
              /* --- cacheline 1 boundary (64 bytes) was 16 bytes ago --- */
              long unsigned int          nrpages;              /*    80     8 */
              long unsigned int          nrexceptional;        /*    88     8 */
              long unsigned int          writeback_index;      /*    96     8 */
              const struct address_space_operations  * a_ops;  /*   104     8 */
              long unsigned int          flags;                /*   112     8 */
              spinlock_t                 private_lock;         /*   120     4 */
      
              /* XXX 4 bytes hole, try to pack */
      
              /* --- cacheline 2 boundary (128 bytes) --- */
              struct list_head           private_list;         /*   128    16 */
              void *                     private_data;         /*   144     8 */
      
              /* size: 152, cachelines: 3, members: 14 */
              /* sum members: 148, holes: 1, sum holes: 4 */
              /* last cacheline: 24 bytes */
      };
      
      Link: http://lkml.kernel.org/r/20160912114852.GI14524@dhcp22.suse.czSigned-off-by: NMichal Hocko <mhocko@suse.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9c5d760b
    • M
      treewide: remove redundant #include <linux/kconfig.h> · 97139d4a
      Masahiro Yamada 提交于
      Kernel source files need not include <linux/kconfig.h> explicitly
      because the top Makefile forces to include it with:
      
        -include $(srctree)/include/linux/kconfig.h
      
      This commit removes explicit includes except the following:
      
        * arch/s390/include/asm/facilities_src.h
        * tools/testing/radix-tree/linux/kernel.h
      
      These two are used for host programs.
      
      Link: http://lkml.kernel.org/r/1473656164-11929-1-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      97139d4a
    • J
      kthread: add kerneldoc for kthread_create() · e154ccc8
      Jonathan Corbet 提交于
      This macro is referenced in other kerneldoc comments, but lacks one of its
      own; fix that.
      
      Link: http://lkml.kernel.org/r/20160826072313.726a3485@lwn.netSigned-off-by: NJonathan Corbet <corbet@lwn.net>
      Reported-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e154ccc8
    • P
      kthread: better support freezable kthread workers · dbf52682
      Petr Mladek 提交于
      This patch allows to make kthread worker freezable via a new @flags
      parameter. It will allow to avoid an init work in some kthreads.
      
      It currently does not affect the function of kthread_worker_fn()
      but it might help to do some optimization or fixes eventually.
      
      I currently do not know about any other use for the @flags
      parameter but I believe that we will want more flags
      in the future.
      
      Finally, I hope that it will not cause confusion with @flags member
      in struct kthread. Well, I guess that we will want to rework the
      basic kthreads implementation once all kthreads are converted into
      kthread workers or workqueues. It is possible that we will merge
      the two structures.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-12-git-send-email-pmladek@suse.comSigned-off-by: NPetr Mladek <pmladek@suse.com>
      Acked-by: NTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      dbf52682
    • P
      kthread: allow to modify delayed kthread work · 9a6b06c8
      Petr Mladek 提交于
      There are situations when we need to modify the delay of a delayed kthread
      work. For example, when the work depends on an event and the initial delay
      means a timeout. Then we want to queue the work immediately when the event
      happens.
      
      This patch implements kthread_mod_delayed_work() as inspired workqueues.
      It cancels the timer, removes the work from any worker list and queues it
      again with the given timeout.
      
      A very special case is when the work is being canceled at the same time.
      It might happen because of the regular kthread_cancel_delayed_work_sync()
      or by another kthread_mod_delayed_work(). In this case, we do nothing and
      let the other operation win. This should not normally happen as the caller
      is supposed to synchronize these operations a reasonable way.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-11-git-send-email-pmladek@suse.comSigned-off-by: NPetr Mladek <pmladek@suse.com>
      Acked-by: NTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9a6b06c8
    • P
      kthread: allow to cancel kthread work · 37be45d4
      Petr Mladek 提交于
      We are going to use kthread workers more widely and sometimes we will need
      to make sure that the work is neither pending nor running.
      
      This patch implements cancel_*_sync() operations as inspired by
      workqueues.  Well, we are synchronized against the other operations via
      the worker lock, we use del_timer_sync() and a counter to count parallel
      cancel operations.  Therefore the implementation might be easier.
      
      First, we check if a worker is assigned.  If not, the work has newer been
      queued after it was initialized.
      
      Second, we take the worker lock.  It must be the right one.  The work must
      not be assigned to another worker unless it is initialized in between.
      
      Third, we try to cancel the timer when it exists.  The timer is deleted
      synchronously to make sure that the timer call back is not running.  We
      need to temporary release the worker->lock to avoid a possible deadlock
      with the callback.  In the meantime, we set work->canceling counter to
      avoid any queuing.
      
      Fourth, we try to remove the work from a worker list. It might be
      the list of either normal or delayed works.
      
      Fifth, if the work is running, we call kthread_flush_work().  It might
      take an arbitrary time.  We need to release the worker-lock again.  In the
      meantime, we again block any queuing by the canceling counter.
      
      As already mentioned, the check for a pending kthread work is done under a
      lock.  In compare with workqueues, we do not need to fight for a single
      PENDING bit to block other operations.  Therefore we do not suffer from
      the thundering storm problem and all parallel canceling jobs might use
      kthread_flush_work().  Any queuing is blocked until the counter gets zero.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-10-git-send-email-pmladek@suse.comSigned-off-by: NPetr Mladek <pmladek@suse.com>
      Acked-by: NTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      37be45d4
    • P
      kthread: initial support for delayed kthread work · 22597dc3
      Petr Mladek 提交于
      We are going to use kthread_worker more widely and delayed works
      will be pretty useful.
      
      The implementation is inspired by workqueues.  It uses a timer to queue
      the work after the requested delay.  If the delay is zero, the work is
      queued immediately.
      
      In compare with workqueues, each work is associated with a single worker
      (kthread).  Therefore the implementation could be much easier.  In
      particular, we use the worker->lock to synchronize all the operations with
      the work.  We do not need any atomic operation with a flags variable.
      
      In fact, we do not need any state variable at all.  Instead, we add a list
      of delayed works into the worker.  Then the pending work is listed either
      in the list of queued or delayed works.  And the existing check of pending
      works is the same even for the delayed ones.
      
      A work must not be assigned to another worker unless reinitialized.
      Therefore the timer handler might expect that dwork->work->worker is valid
      and it could simply take the lock.  We just add some sanity checks to help
      with debugging a potential misuse.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-9-git-send-email-pmladek@suse.comSigned-off-by: NPetr Mladek <pmladek@suse.com>
      Acked-by: NTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      22597dc3
    • P
      kthread: add kthread_destroy_worker() · 35033fe9
      Petr Mladek 提交于
      The current kthread worker users call flush() and stop() explicitly.
      This function does the same plus it frees the kthread_worker struct
      in one call.
      
      It is supposed to be used together with kthread_create_worker*() that
      allocates struct kthread_worker.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-7-git-send-email-pmladek@suse.comSigned-off-by: NPetr Mladek <pmladek@suse.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      35033fe9
    • P
      kthread: add kthread_create_worker*() · fbae2d44
      Petr Mladek 提交于
      Kthread workers are currently created using the classic kthread API,
      namely kthread_run().  kthread_worker_fn() is passed as the @threadfn
      parameter.
      
      This patch defines kthread_create_worker() and
      kthread_create_worker_on_cpu() functions that hide implementation details.
      
      They enforce using kthread_worker_fn() for the main thread.  But I doubt
      that there are any plans to create any alternative.  In fact, I think that
      we do not want any alternative main thread because it would be hard to
      support consistency with the rest of the kthread worker API.
      
      The naming and function of kthread_create_worker() is inspired by the
      workqueues API like the rest of the kthread worker API.
      
      The kthread_create_worker_on_cpu() variant is motivated by the original
      kthread_create_on_cpu().  Note that we need to bind per-CPU kthread
      workers already when they are created.  It makes the life easier.
      kthread_bind() could not be used later for an already running worker.
      
      This patch does _not_ convert existing kthread workers.  The kthread
      worker API need more improvements first, e.g.  a function to destroy the
      worker.
      
      IMPORTANT:
      
      kthread_create_worker_on_cpu() allows to use any format of the worker
      name, in compare with kthread_create_on_cpu().  The good thing is that it
      is more generic.  The bad thing is that most users will need to pass the
      cpu number in two parameters, e.g.  kthread_create_worker_on_cpu(cpu,
      "helper/%d", cpu).
      
      To be honest, the main motivation was to avoid the need for an empty
      va_list.  The only legal way was to create a helper function that would be
      called with an empty list.  Other attempts caused compilation warnings or
      even errors on different architectures.
      
      There were also other alternatives, for example, using #define or
      splitting __kthread_create_worker().  The used solution looked like the
      least ugly.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-6-git-send-email-pmladek@suse.comSigned-off-by: NPetr Mladek <pmladek@suse.com>
      Acked-by: NTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      fbae2d44
    • P
      kthread: kthread worker API cleanup · 3989144f
      Petr Mladek 提交于
      A good practice is to prefix the names of functions by the name
      of the subsystem.
      
      The kthread worker API is a mix of classic kthreads and workqueues.  Each
      worker has a dedicated kthread.  It runs a generic function that process
      queued works.  It is implemented as part of the kthread subsystem.
      
      This patch renames the existing kthread worker API to use
      the corresponding name from the workqueues API prefixed by
      kthread_:
      
      __init_kthread_worker()		-> __kthread_init_worker()
      init_kthread_worker()		-> kthread_init_worker()
      init_kthread_work()		-> kthread_init_work()
      insert_kthread_work()		-> kthread_insert_work()
      queue_kthread_work()		-> kthread_queue_work()
      flush_kthread_work()		-> kthread_flush_work()
      flush_kthread_worker()		-> kthread_flush_worker()
      
      Note that the names of DEFINE_KTHREAD_WORK*() macros stay
      as they are. It is common that the "DEFINE_" prefix has
      precedence over the subsystem names.
      
      Note that INIT() macros and init() functions use different
      naming scheme. There is no good solution. There are several
      reasons for this solution:
      
        + "init" in the function names stands for the verb "initialize"
          aka "initialize worker". While "INIT" in the macro names
          stands for the noun "INITIALIZER" aka "worker initializer".
      
        + INIT() macros are used only in DEFINE() macros
      
        + init() functions are used close to the other kthread()
          functions. It looks much better if all the functions
          use the same scheme.
      
        + There will be also kthread_destroy_worker() that will
          be used close to kthread_cancel_work(). It is related
          to the init() function. Again it looks better if all
          functions use the same naming scheme.
      
        + there are several precedents for such init() function
          names, e.g. amd_iommu_init_device(), free_area_init_node(),
          jump_label_init_type(),  regmap_init_mmio_clk(),
      
        + It is not an argument but it was inconsistent even before.
      
      [arnd@arndb.de: fix linux-next merge conflict]
       Link: http://lkml.kernel.org/r/20160908135724.1311726-1-arnd@arndb.de
      Link: http://lkml.kernel.org/r/1470754545-17632-3-git-send-email-pmladek@suse.comSuggested-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NPetr Mladek <pmladek@suse.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: NArnd Bergmann <arnd@arndb.de>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3989144f
    • P
      kthread: rename probe_kthread_data() to kthread_probe_data() · e700591a
      Petr Mladek 提交于
      Patch series "kthread: Kthread worker API improvements"
      
      The intention of this patchset is to make it easier to manipulate and
      maintain kthreads.  Especially, I want to replace all the custom main
      cycles with a generic one.  Also I want to make the kthreads sleep in a
      consistent state in a common place when there is no work.
      
      This patch (of 11):
      
      A good practice is to prefix the names of functions by the name of the
      subsystem.
      
      This patch fixes the name of probe_kthread_data().  The other wrong
      functions names are part of the kthread worker API and will be fixed
      separately.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-2-git-send-email-pmladek@suse.comSigned-off-by: NPetr Mladek <pmladek@suse.com>
      Suggested-by: NAndrew Morton <akpm@linux-foundation.org>
      Acked-by: NTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e700591a
    • C
      mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping · 9099daed
      Catalin Marinas 提交于
      Some of the kmemleak_*() callbacks in memblock, bootmem, CMA convert a
      physical address to a virtual one using __va().  However, such physical
      addresses may sometimes be located in highmem and using __va() is
      incorrect, leading to inconsistent object tracking in kmemleak.
      
      The following functions have been added to the kmemleak API and they take
      a physical address as the object pointer.  They only perform the
      corresponding action if the address has a lowmem mapping:
      
      kmemleak_alloc_phys
      kmemleak_free_part_phys
      kmemleak_not_leak_phys
      kmemleak_ignore_phys
      
      The affected calling places have been updated to use the new kmemleak
      API.
      
      Link: http://lkml.kernel.org/r/1471531432-16503-1-git-send-email-catalin.marinas@arm.comSigned-off-by: NCatalin Marinas <catalin.marinas@arm.com>
      Reported-by: NVignesh R <vigneshr@ti.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9099daed
    • T
      kdump, vmcoreinfo: report memory sections virtual addresses · 0549a3c0
      Thomas Garnier 提交于
      KASLR memory randomization can randomize the base of the physical memory
      mapping (PAGE_OFFSET), vmalloc (VMALLOC_START) and vmemmap
      (VMEMMAP_START).  Adding these variables on VMCOREINFO so tools can easily
      identify the base of each memory section.
      
      Link: http://lkml.kernel.org/r/1471531632-23003-1-git-send-email-thgarnie@google.comSigned-off-by: NThomas Garnier <thgarnie@google.com>
      Acked-by: NBaoquan He <bhe@redhat.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: "H . Peter Anvin" <hpa@zytor.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Xunlei Pang <xlpang@redhat.com>
      Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Eugene Surovegin <surovegin@google.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0549a3c0
    • M
      ipc/sem.c: fix complex_count vs. simple op race · 5864a2fd
      Manfred Spraul 提交于
      Commit 6d07b68c ("ipc/sem.c: optimize sem_lock()") introduced a
      race:
      
      sem_lock has a fast path that allows parallel simple operations.
      There are two reasons why a simple operation cannot run in parallel:
       - a non-simple operations is ongoing (sma->sem_perm.lock held)
       - a complex operation is sleeping (sma->complex_count != 0)
      
      As both facts are stored independently, a thread can bypass the current
      checks by sleeping in the right positions.  See below for more details
      (or kernel bugzilla 105651).
      
      The patch fixes that by creating one variable (complex_mode)
      that tracks both reasons why parallel operations are not possible.
      
      The patch also updates stale documentation regarding the locking.
      
      With regards to stable kernels:
      The patch is required for all kernels that include the
      commit 6d07b68c ("ipc/sem.c: optimize sem_lock()") (3.10?)
      
      The alternative is to revert the patch that introduced the race.
      
      The patch is safe for backporting, i.e. it makes no assumptions
      about memory barriers in spin_unlock_wait().
      
      Background:
      Here is the race of the current implementation:
      
      Thread A: (simple op)
      - does the first "sma->complex_count == 0" test
      
      Thread B: (complex op)
      - does sem_lock(): This includes an array scan. But the scan can't
        find Thread A, because Thread A does not own sem->lock yet.
      - the thread does the operation, increases complex_count,
        drops sem_lock, sleeps
      
      Thread A:
      - spin_lock(&sem->lock), spin_is_locked(sma->sem_perm.lock)
      - sleeps before the complex_count test
      
      Thread C: (complex op)
      - does sem_lock (no array scan, complex_count==1)
      - wakes up Thread B.
      - decrements complex_count
      
      Thread A:
      - does the complex_count test
      
      Bug:
      Now both thread A and thread C operate on the same array, without
      any synchronization.
      
      Fixes: 6d07b68c ("ipc/sem.c: optimize sem_lock()")
      Link: http://lkml.kernel.org/r/1469123695-5661-1-git-send-email-manfred@colorfullife.com
      Reported-by: <felixh@informatik.uni-bremen.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Davidlohr Bueso <dave@stgolabs.net>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: <1vier1@web.de>
      Cc: <stable@vger.kernel.org>	[3.10+]
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5864a2fd
    • P
      relay: Use irq_work instead of plain timer for deferred wakeup · 26b5679e
      Peter Zijlstra 提交于
      Relay avoids calling wake_up_interruptible() for doing the wakeup of
      readers/consumers, waiting for the generation of new data, from the
      context of a process which produced the data.  This is apparently done to
      prevent the possibility of a deadlock in case Scheduler itself is is
      generating data for the relay, after acquiring rq->lock.
      
      The following patch used a timer (to be scheduled at next jiffy), for
      delegating the wakeup to another context.
      	commit 7c9cb383
      	Author: Tom Zanussi <zanussi@comcast.net>
      	Date:   Wed May 9 02:34:01 2007 -0700
      
      	relay: use plain timer instead of delayed work
      
      	relay doesn't need to use schedule_delayed_work() for waking readers
      	when a simple timer will do.
      
      Scheduling a plain timer, at next jiffies boundary, to do the wakeup
      causes a significant wakeup latency for the Userspace client, which makes
      relay less suitable for the high-frequency low-payload use cases where the
      data gets generated at a very high rate, like multiple sub buffers getting
      filled within a milli second.  Moreover the timer is re-scheduled on every
      newly produced sub buffer so the timer keeps getting pushed out if sub
      buffers are filled in a very quick succession (less than a jiffy gap
      between filling of 2 sub buffers).  As a result relay runs out of sub
      buffers to store the new data.
      
      By using irq_work it is ensured that wakeup of userspace client, blocked
      in the poll call, is done at earliest (through self IPI or next timer
      tick) enabling it to always consume the data in time.  Also this makes
      relay consistent with printk & ring buffers (trace), as they too use
      irq_work for deferred wake up of readers.
      
      [arnd@arndb.de: select CONFIG_IRQ_WORK]
       Link: http://lkml.kernel.org/r/20160912154035.3222156-1-arnd@arndb.de
      [akpm@linux-foundation.org: coding-style fixes]
      Link: http://lkml.kernel.org/r/1472906487-1559-1-git-send-email-akash.goel@intel.comSigned-off-by: NPeter Zijlstra <peterz@infradead.org>
      Signed-off-by: NAkash Goel <akash.goel@intel.com>
      Cc: Tom Zanussi <tzanussi@gmail.com>
      Cc: Chris Wilson <chris@chris-wilson.co.uk>
      Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
      Signed-off-by: NArnd Bergmann <arnd@arndb.de>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      26b5679e
    • M
      dma-mapping: introduce the DMA_ATTR_NO_WARN attribute · a9a62c93
      Mauricio Faria de Oliveira 提交于
      Introduce the DMA_ATTR_NO_WARN attribute, and document it.
      
      Link: http://lkml.kernel.org/r/1470092390-25451-2-git-send-email-mauricfo@linux.vnet.ibm.comSigned-off-by: NMauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
      Cc: Keith Busch <keith.busch@intel.com>
      Cc: Jens Axboe <axboe@fb.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a9a62c93
    • J
      random: remove unused randomize_range() · 7425154d
      Jason Cooper 提交于
      All call sites for randomize_range have been updated to use the much
      simpler and more robust randomize_addr().  Remove the now unnecessary
      code.
      
      Link: http://lkml.kernel.org/r/20160803233913.32511-8-jason@lakedaemon.netSigned-off-by: NJason Cooper <jason@lakedaemon.net>
      Acked-by: NKees Cook <keescook@chromium.org>
      Cc: "Theodore Ts'o" <tytso@mit.edu>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7425154d
    • J
      random: simplify API for random address requests · 99fdafde
      Jason Cooper 提交于
      To date, all callers of randomize_range() have set the length to 0, and
      check for a zero return value.  For the current callers, the only way to
      get zero returned is if end <= start.  Since they are all adding a
      constant to the start address, this is unnecessary.
      
      We can remove a bunch of needless checks by simplifying the API to do just
      what everyone wants, return an address between [start, start + range).
      
      While we're here, s/get_random_int/get_random_long/.  No current call site
      is adversely affected by get_random_int(), since all current range
      requests are < UINT_MAX.  However, we should match caller expectations to
      avoid coming up short (ha!) in the future.
      
      All current callers to randomize_range() chose to use the start address if
      randomize_range() failed.  Therefore, we simplify things by just returning
      the start address on error.
      
      randomize_range() will be removed once all callers have been converted
      over to randomize_addr().
      
      Link: http://lkml.kernel.org/r/20160803233913.32511-2-jason@lakedaemon.netSigned-off-by: NJason Cooper <jason@lakedaemon.net>
      Acked-by: NKees Cook <keescook@chromium.org>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Cc: "Roberts, William C" <william.c.roberts@intel.com>
      Cc: Yann Droneaud <ydroneaud@opteya.com>
      Cc: Russell King <linux@arm.linux.org.uk>
      Cc: "Theodore Ts'o" <tytso@mit.edu>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: "David S. Miller" <davem@davemloft.net>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: "H . Peter Anvin" <hpa@zytor.com>
      Cc: Nick Kralevich <nnk@google.com>
      Cc: Jeffrey Vander Stoep <jeffv@google.com>
      Cc: Daniel Cashman <dcashman@android.com>
      Cc: Chris Metcalf <cmetcalf@mellanox.com>
      Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      99fdafde
    • I
      autofs4: move linux/auto_dev-ioctl.h to uapi/linux · 9b88ee0f
      Ian Kent 提交于
      Since linux/auto_dev-ioctl.h wasn't included in include/linux/Kbuild
      it wasn't moved to uapi/linux as part of the uapi series.
      
      Link: http://lkml.kernel.org/r/20160812024901.12352.10984.stgit@pluto.themaw.netSigned-off-by: NIan Kent <raven@themaw.net>
      Cc: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9b88ee0f
    • T
      autofs: move inclusion of linux/limits.h to uapi · f58b3c91
      Tomohiro Kusumi 提交于
      linux/limits.h should be included by uapi instead of linux/auto_fs.h
      so as not to cause compile error in userspace.
      
       # cat << EOF > ./test1.c
       > #include <stdio.h>
       > #include <linux/auto_fs.h>
       > int main(void) {
       >     return 0;
       > }
       > EOF
       # gcc -Wall -g ./test1.c
       In file included from ./test1.c:2:0:
       /usr/include/linux/auto_fs.h:54:12: error: 'NAME_MAX' undeclared here (not in a function)
         char name[NAME_MAX+1];
                   ^
      
      Link: http://lkml.kernel.org/r/20160812024856.12352.24092.stgit@pluto.themaw.netSigned-off-by: NTomohiro Kusumi <kusumi.tomohiro@gmail.com>
      Signed-off-by: NIan Kent <ikent@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f58b3c91
    • T
      autofs: remove AUTOFS_DEVID_LEN · 72063e01
      Tomohiro Kusumi 提交于
      This macro was never used by neither kernel nor userspace, and also
      doesn't represent "devid length" in bytes.  (unless it was added to mean
      something else).
      
      Link: http://lkml.kernel.org/r/20160812024820.12352.21210.stgit@pluto.themaw.netSigned-off-by: NTomohiro Kusumi <kusumi.tomohiro@gmail.com>
      Signed-off-by: NIan Kent <ikent@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      72063e01
    • A
      include/linux/ctype.h: make isdigit() table lookupless · 1204c77f
      Alexey Dobriyan 提交于
      Make isdigit into a simple range checking inline function:
      
      	return '0' <= c && c <= '9';
      
      This code is 1 branch, not 2 because any reasonable compiler can
      optimize this code into SUB+CMP, so the code
      
      	while (isdigit((c = *s++)))
      		...
      
      remains 1 branch per iteration HOWEVER it suddenly doesn't do table
      lookup priming cacheline nobody cares about.
      
      Link: http://lkml.kernel.org/r/20160826190047.GA12536@p183.telecom.bySigned-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1204c77f
    • R
      radix-tree: 'slot' can be NULL in radix_tree_next_slot() · 915045fe
      Ross Zwisler 提交于
      There are four cases I can see where we could end up with a NULL 'slot' in
      radix_tree_next_slot().  Yet radix_tree_next_slot() never actually checks
      whether 'slot' is NULL.  It just happens that for the cases where 'slot'
      is NULL, some other combination of factors prevents us from dereferencing
      it.
      
      It would be very easy for someone to unwittingly change one of these
      factors without realizing that we are implicitly depending on it to save
      us from a NULL pointer dereference.
      
      Add a comment documenting the things that allow 'slot' to be safely passed
      as NULL to radix_tree_next_slot().
      
      Here are details on the four cases:
      
      1) radix_tree_iter_retry() via a non-tagged iteration like
      radix_tree_for_each_slot().  In this case we currently aren't seeing a bug
      because radix_tree_iter_retry() sets
      
      	iter->next_index = iter->index;
      
      which means that in in the else case in radix_tree_next_slot(), 'count' is
      zero, so we skip over the while() loop and effectively just return NULL
      without ever dereferencing 'slot'.
      
      2) radix_tree_iter_retry() via tagged iteration like
      radix_tree_for_each_tagged().  This case was giving us NULL pointer
      dereferences in testing, and was fixed with this commit:
      
      commit 3cb9185c ("radix-tree: fix radix_tree_iter_retry() for tagged
      iterators.")
      
      This fix doesn't explicitly check for 'slot' being NULL, though, it works
      around the NULL pointer dereference by instead zeroing iter->tags in
      radix_tree_iter_retry(), which makes us bail out of the if() case in
      radix_tree_next_slot() before we dereference 'slot'.
      
      3) radix_tree_iter_next() via via a non-tagged iteration like
      radix_tree_for_each_slot().  This currently happens in shmem_tag_pins()
      and shmem_partial_swap_usage().
      
      As with non-tagged iteration, 'count' in the else case of
      radix_tree_next_slot() is zero, so we skip over the while() loop and
      effectively just return NULL without ever dereferencing 'slot'.
      
      4) radix_tree_iter_next() via tagged iteration like
      radix_tree_for_each_tagged().  This happens in shmem_wait_for_pins().
      
      radix_tree_iter_next() zeros out iter->tags, so we end up exiting
      radix_tree_next_slot() here:
      
      	if (flags & RADIX_TREE_ITER_TAGGED) {
      		void *canon = slot;
      
      		iter->tags >>= 1;
      		if (unlikely(!iter->tags))
      			return NULL;
      
      Link: http://lkml.kernel.org/r/20160815194237.25967-2-ross.zwisler@linux.intel.comSigned-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
      Cc: Konstantin Khlebnikov <koct9i@gmail.com>
      Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Shuah Khan <shuahkh@osg.samsung.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      915045fe
  2. 11 10月, 2016 1 次提交
  3. 10 10月, 2016 4 次提交
    • J
    • G
      drm: use the right function name in documentation · 621a9993
      Grazvydas Ignotas 提交于
      There is no late_unregister(), it looks like the comment meant
      late_register(). Also fix a typo while at it.
      Signed-off-by: NGrazvydas Ignotas <notasas@gmail.com>
      Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      Link: http://patchwork.freedesktop.org/patch/msgid/1476032820-3275-1-git-send-email-notasas@gmail.com
      621a9993
    • S
      drm/fb-helper: fix sphinx markup for DRM_FB_HELPER_DEFAULT_OPS · 21bf75ec
      Stefan Christ 提交于
      Fix invalid sphinx markup in the comment for the newly added
      DRM_FB_HELPER_DEFAULT_OPS.
      Signed-off-by: NStefan Christ <contact@stefanchrist.eu>
      Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      Link: http://patchwork.freedesktop.org/patch/msgid/1475692454-11543-1-git-send-email-contact@stefanchrist.eu
      21bf75ec
    • L
      printk: reinstate KERN_CONT for printing continuation lines · 4bcc595c
      Linus Torvalds 提交于
      Long long ago the kernel log buffer was a buffered stream of bytes, very
      much like stdio in user space.  It supported log levels by scanning the
      stream and noticing the log level markers at the beginning of each line,
      but if you wanted to print a partial line in multiple chunks, you just
      did multiple printk() calls, and it just automatically worked.
      
      Except when it didn't, and you had very confusing output when different
      lines got all mixed up with each other.  Then you got fragment lines
      mixing with each other, or with non-fragment lines, because it was
      traditionally impossible to tell whether a printk() call was a
      continuation or not.
      
      To at least help clarify the issue of continuation lines, we added a
      KERN_CONT marker back in 2007 to mark continuation lines:
      
        47492527 ("printk: add KERN_CONT annotation").
      
      That continuation marker was initially an empty string, and didn't
      actuall make any semantic difference.  But it at least made it possible
      to annotate the source code, and have check-patch notice that a printk()
      didn't need or want a log level marker, because it was a continuation of
      a previous line.
      
      To avoid the ambiguity between a continuation line that had that
      KERN_CONT marker, and a printk with no level information at all, we then
      in 2009 made KERN_CONT be a real log level marker which meant that we
      could now reliably tell the difference between the two cases.
      
        5fd29d6c ("printk: clean up handling of log-levels and newlines")
      
      and we could take advantage of that to make sure we didn't mix up
      continuation lines with lines that just didn't have any loglevel at all.
      
      Then, in 2012, the kernel log buffer was changed to be a "record" based
      log, where each line was a record that has a loglevel and a timestamp.
      
      You can see the beginning of that conversion in commits
      
        e11fea92 ("kmsg: export printk records to the /dev/kmsg interface")
        7ff9554b ("printk: convert byte-buffer to variable-length record buffer")
      
      with a number of follow-up commits to fix some painful fallout from that
      conversion.  Over all, it took a couple of months to sort out most of
      it.  But the upside was that you could have concurrent readers (and
      writers) of the kernel log and not have lines with mixed output in them.
      
      And one particular pain-point for the record-based kernel logging was
      exactly the fragmentary lines that are generated in smaller chunks.  In
      order to still log them as one recrod, the continuation lines need to be
      attached to the previous record properly.
      
      However the explicit continuation record marker that is actually useful
      for this exact case was actually removed in aroundm the same time by commit
      
        61e99ab8 ("printk: remove the now unnecessary "C" annotation for KERN_CONT")
      
      due to the incorrect belief that KERN_CONT wasn't meaningful.  The
      ambiguity between "is this a continuation line" or "is this a plain
      printk with no log level information" was reintroduced, and in fact
      became an even bigger pain point because there was now the whole
      record-level merging of kernel messages going on.
      
      This patch reinstates the KERN_CONT as a real non-empty string marker,
      so that the ambiguity is fixed once again.
      
      But it's not a plain revert of that original removal: in the four years
      since we made KERN_CONT an empty string again, not only has the format
      of the log level markers changed, we've also had some usage changes in
      this area.
      
      For example, some ACPI code seems to use KERN_CONT _together_ with a log
      level, and now uses both the KERN_CONT marker and (for example) a
      KERN_INFO marker to show that it's an informational continuation of a
      line.
      
      Which is actually not a bad idea - if the continuation line cannot be
      attached to its predecessor, without the log level information we don't
      know what log level to assign to it (and we traditionally just assigned
      it the default loglevel).  So having both a log level and the KERN_CONT
      marker is not necessarily a bad idea, but it does mean that we need to
      actually iterate over potentially multiple markers, rather than just a
      single one.
      
      Also, since KERN_CONT was still conceptually needed, and encouraged, but
      didn't actually _do_ anything, we've also had the reverse problem:
      rather than having too many annotations it has too few, and there is bit
      rot with code that no longer marks the continuation lines with the
      KERN_CONT marker.
      
      So this patch not only re-instates the non-empty KERN_CONT marker, it
      also fixes up the cases of bit-rot I noticed in my own logs.
      
      There are probably other cases where KERN_CONT will be needed to be
      added, either because it is new code that never dealt with the need for
      KERN_CONT, or old code that has bitrotted without anybody noticing.
      
      That said, we should strive to avoid the need for KERN_CONT.  It does
      result in real problems for logging, and should generally not be seen as
      a good feature.  If we some day can get rid of the feature entirely,
      because nobody does any fragmented printk calls, that would be lovely.
      
      But until that point, let's at mark the code that relies on the hacky
      multi-fragment kernel printk's.  Not only does it avoid the ambiguity,
      it also annotates code as "maybe this would be good to fix some day".
      
      (That said, particularly during single-threaded bootup, the downsides of
      KERN_CONT are very limited.  Things get much hairier when you have
      multiple threads going on and user level reading and writing logs too).
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4bcc595c
  4. 08 10月, 2016 11 次提交