linux-toradex.git/drivers/base/core.c, branch v4.18-rc4

PM / core: Fix supplier device runtime PM usage counter imbalance

2018-06-14T08:01:52+00:00

If a device link is added via device_link_add() by the driver of the
link's consumer device, the supplier's runtime PM usage counter is
going to be dropped by the pm_runtime_put_suppliers() call in
driver_probe_device().  However, in that case it is not incremented
unless the supplier driver is already present and the link is not
stateless.  That leads to a runtime PM usage counter imbalance for
the supplier device in a few cases.

To prevent that from happening, bump up the supplier runtime
PM usage counter in device_link_add() for all links with the
DL_FLAG_PM_RUNTIME flag set that are added at the consumer probe
time.  Use pm_runtime_get_noresume() for that as the callers of
device_link_add() who want the supplier to be resumed by it are
expected to pass DL_FLAG_RPM_ACTIVE in flags to it anyway, but
additionally resume the supplier if the link is added during
consumer driver probe to retain the existing behavior for the
callers depending on it.

Fixes: 21d5c57b3726 (PM / runtime: Use device links)
Reported-by: Ulf Hansson 
Reviewed-by: Ulf Hansson 
Tested-by: Marek Szyprowski 
Cc: 4.10+  # 4.10+
Signed-off-by: Rafael J. Wysocki

Merge tag 'driver-core-4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2018-06-05T23:29:19+00:00

Pull driver core updates from Greg KH:
 "Here is the driver core patchset for 4.18-rc1.

  The large chunk of these are firmware core documentation and api
  updates. Nothing major there, just better descriptions for others to
  be able to understand the firmware code better. There's also a user
  for a new firmware api call.

  Other than that, there are some minor updates for debugfs, kernfs, and
  the driver core itself.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'driver-core-4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (23 commits)
  driver core: hold dev's parent lock when needed
  driver-core: return EINVAL error instead of BUG_ON()
  driver core: add __printf verification to device_create_groups_vargs
  mm: memory_hotplug: use put_device() if device_register fail
  base: core: fix typo 'can by' to 'can be'
  debugfs: inode: debugfs_create_dir uses mode permission from parent
  debugfs: Re-use kstrtobool_from_user()
  Documentation: clarify firmware_class provenance and why we can't rename the module
  Documentation: remove stale firmware API reference
  Documentation: fix few typos and clarifications for the firmware loader
  ath10k: re-enable the firmware fallback mechanism for testmode
  ath10k: use firmware_request_nowarn() to load firmware
  firmware: add firmware_request_nowarn() - load firmware without warnings
  firmware_loader: make firmware_fallback_sysfs() print more useful
  firmware_loader: move kconfig FW_LOADER entries to its own file
  firmware_loader: replace ---help--- with help
  firmware_loader: enhance Kconfig documentation over FW_LOADER
  firmware_loader: document firmware_sysfs_fallback()
  firmware: rename fw_sysfs_fallback to firmware_fallback_sysfs()
  firmware: use () to terminate kernel-doc function names
  ...

driver core: add __printf verification to device_create_groups_vargs

2018-05-14T14:59:21+00:00

__printf is useful to verify format and arguments. Remove the following
warning (with W=1):

  drivers/base/core.c:2435:2: warning: function might be possible candidate for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format]

Signed-off-by: Mathieu Malaterre 
Signed-off-by: Greg Kroah-Hartman

base: core: fix typo 'can by' to 'can be'

2018-05-14T14:48:59+00:00

Signed-off-by: Wolfram Sang 
Signed-off-by: Greg Kroah-Hartman

driver core: Don't ignore class_dir_create_and_add() failure.

2018-05-14T14:37:46+00:00

syzbot is hitting WARN() at kernfs_add_one() [1].
This is because kernfs_create_link() is confused by previous device_add()
call which continued without setting dev->kobj.parent field when
get_device_parent() failed by memory allocation fault injection.
Fix this by propagating the error from class_dir_create_and_add() to
the calllers of get_device_parent().

[1] https://syzkaller.appspot.com/bug?id=fae0fb607989ea744526d1c082a5b8de6529116f

Signed-off-by: Tetsuo Handa 
Reported-by: syzbot 
Cc: Greg Kroah-Hartman 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

PM / core: fix deferred probe breaking suspend resume order

2018-04-24T10:18:25+00:00

When bridge and its endpoint is enumerated the devices are added to the
dpm list. Afterward, the bridge defers probe when IOMMU is not ready.
This causes the bridge to be moved to the end of the dpm list when
deferred probe kicks in. The order of the dpm list for bridge and
endpoint is reversed.

Add reordering code to move the bridge and its children and consumers to
the end of the pm list so the order for suspend and resume is not altered.
The code also move device and its children and consumers to the tail of
device_kset list if it is registered.

Signed-off-by: Toan Le 
Signed-off-by: Feng Kan 
Reviewed-by: Greg Kroah-Hartman 
Signed-off-by: Rafael J. Wysocki

driver core: Introduce device links reference counting

2018-02-27T17:10:42+00:00

If device_link_add() is invoked multiple times with the same supplier
and consumer combo, it will create the link on first addition and
return a pointer to the already existing link on all subsequent
additions.

The semantics for device_link_del() are quite different, it deletes
the link unconditionally, so multiple invocations are not allowed.

In other words, this snippet ...

    struct device *dev1, *dev2;
    struct device_link *link1, *link2;

    link1 = device_link_add(dev1, dev2, 0);
    link2 = device_link_add(dev1, dev2, 0);

    device_link_del(link1);
    device_link_del(link2);

... causes the following crash:

    WARNING: CPU: 4 PID: 2686 at drivers/base/power/runtime.c:1611 pm_runtime_drop_link+0x40/0x50
    [...]
    list_del corruption, 0000000039b800a4->prev is LIST_POISON2 (00000000ecf79852)
    kernel BUG at lib/list_debug.c:50!

The issue isn't as arbitrary as it may seem:  Imagine a device link
which is added in both the supplier's and the consumer's ->probe hook.
The two drivers can't just call device_link_del() in their ->remove hook
without coordination.

Fix by counting multiple additions and dropping the device link only
when the last addition is unwound.

Signed-off-by: Lukas Wunner 
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki

PM / runtime: Update links_count also if !CONFIG_SRCU

2018-02-12T10:12:58+00:00

Commit baa8809f6097 (PM / runtime: Optimize the use of device links)
added an invocation of pm_runtime_drop_link() to __device_link_del().
However there are two variants of that function, one for CONFIG_SRCU and
another for !CONFIG_SRCU, and the commit only modified the former.

Fixes: baa8809f6097 (PM / runtime: Optimize the use of device links)
Cc: v4.10+  # v4.10+
Signed-off-by: Lukas Wunner 
Signed-off-by: Rafael J. Wysocki

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk

2018-02-01T21:36:15+00:00

Pull printk updates from Petr Mladek:

 - Add a console_msg_format command line option:

     The value "default" keeps the old "[time stamp] text\n" format. The
     value "syslog" allows to see the syslog-like "[timestamp] text" format.

     This feature was requested by people doing regression tests, for
     example, 0day robot. They want to have both filtered and full logs
     at hands.

 - Reduce the risk of softlockup:

     Pass the console owner in a busy loop.

     This is a new approach to the old problem. It was first proposed by
     Steven Rostedt on Kernel Summit 2017. It marks a context in which
     the console_lock owner calls console drivers and could not sleep.
     On the other side, printk() callers could detect this state and use
     a busy wait instead of a simple console_trylock(). Finally, the
     console_lock owner checks if there is a busy waiter at the end of
     the special context and eventually passes the console_lock to the
     waiter.

     The hand-off works surprisingly well and helps in many situations.
     Well, there is still a possibility of the softlockup, for example,
     when the flood of messages stops and the last owner still has too
     much to flush.

     There is increasing number of people having problems with
     printk-related softlockups. We might eventually need to get better
     solution. Anyway, this looks like a good start and promising
     direction.

 - Do not allow to schedule in console_unlock() called from printk():

     This reverts an older controversial commit. The reschedule helped
     to avoid softlockups. But it also slowed down the console output.
     This patch is obsoleted by the new console waiter logic described
     above. In fact, the reschedule made the hand-off less effective.

 - Deprecate "%pf" and "%pF" format specifier:

     It was needed on ia64, ppc64 and parisc64 to dereference function
     descriptors and show the real function address. It is done
     transparently by "%ps" and "pS" format specifier now.

     Sergey Senozhatsky found that all the function descriptors were in
     a special elf section and could be easily detected.

 - Remove printk_symbol() API:

     It has been obsoleted by "%pS" format specifier, and this change
     helped to remove few continuous lines and a less intuitive old API.

 - Remove redundant memsets:

     Sergey removed unnecessary memset when processing printk.devkmsg
     command line option.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk: (27 commits)
  printk: drop redundant devkmsg_log_str memsets
  printk: Never set console_may_schedule in console_trylock()
  printk: Hide console waiter logic into helpers
  printk: Add console owner and waiter logic to load balance console writes
  kallsyms: remove print_symbol() function
  checkpatch: add pF/pf deprecation warning
  symbol lookup: introduce dereference_symbol_descriptor()
  parisc64: Add .opd based function descriptor dereference
  powerpc64: Add .opd based function descriptor dereference
  ia64: Add .opd based function descriptor dereference
  sections: split dereference_function_descriptor()
  openrisc: Fix conflicting types for _exext and _stext
  lib: do not use print_symbol()
  irq debug: do not use print_symbol()
  sysfs: do not use print_symbol()
  drivers: do not use print_symbol()
  x86: do not use print_symbol()
  unicore32: do not use print_symbol()
  sh: do not use print_symbol()
  mn10300: do not use print_symbol()
  ...

drivers: do not use print_symbol()

2018-01-05T14:23:59+00:00

print_symbol() is a very old API that has been obsoleted by %pS format
specifier in a normal printk() call.

Replace print_symbol() with a direct printk("%pS") call.

Link: http://lkml.kernel.org/r/20171211125025.2270-10-sergey.senozhatsky@gmail.com
To: Andrew Morton 
To: Russell King 
To: Catalin Marinas 
To: Mark Salter 
To: Tony Luck 
To: David Howells 
To: Yoshinori Sato 
To: Guan Xuetao 
To: Borislav Petkov 
To: Greg Kroah-Hartman 
To: Thomas Gleixner 
To: Peter Zijlstra 
To: Vineet Gupta 
To: Fengguang Wu 
Cc: Steven Rostedt 
Cc: Petr Mladek 
Cc: LKML 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-am33-list@redhat.com
Cc: linux-sh@vger.kernel.org
Cc: linux-edac@vger.kernel.org
Cc: x86@kernel.org
Cc: linux-snps-arc@lists.infradead.org
Signed-off-by: Sergey Senozhatsky 
[pmladek@suse.com: updated commit message]
Signed-off-by: Petr Mladek