<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux/lib/Kconfig.debug, branch v5.7</title>
<subtitle>Mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
</subtitle>
<id>https://git.shady.money/linux/atom?h=v5.7</id>
<link rel='self' href='https://git.shady.money/linux/atom?h=v5.7'/>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/'/>
<updated>2020-04-10T00:39:22Z</updated>
<entry>
<title>Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf</title>
<updated>2020-04-10T00:39:22Z</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2020-04-10T00:39:22Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=40fc7ad2c8863479f3db34f9a9283b4884cd0e90'/>
<id>urn:sha1:40fc7ad2c8863479f3db34f9a9283b4884cd0e90</id>
<content type='text'>
Daniel Borkmann says:

====================
pull-request: bpf 2020-04-10

The following pull-request contains BPF updates for your *net* tree.

We've added 13 non-merge commits during the last 7 day(s) which contain
a total of 13 files changed, 137 insertions(+), 43 deletions(-).

The main changes are:

1) JIT code emission fixes for riscv and arm32, from Luke Nelson and Xi Wang.

2) Disable vmlinux BTF info if GCC_PLUGIN_RANDSTRUCT is used, from Slava Bacherikov.

3) Fix oob write in AF_XDP when meta data is used, from Li RongQing.

4) Fix bpf_get_link_xdp_id() handling on single prog when flags are specified,
   from Andrey Ignatov.

5) Fix sk_assign() BPF helper for request sockets that can have sk_reuseport
   field uninitialized, from Joe Stringer.

6) Fix mprotect() test case for the BPF LSM, from KP Singh.
====================

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>lib/Kconfig.debug: fix a typo "capabilitiy" -&gt; "capability"</title>
<updated>2020-04-07T17:43:44Z</updated>
<author>
<name>Qiujun Huang</name>
<email>hqjagain@gmail.com</email>
</author>
<published>2020-04-07T03:12:49Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=29b46fa3dc57def8af3cec1d4e2984b5150be9d5'/>
<id>urn:sha1:29b46fa3dc57def8af3cec1d4e2984b5150be9d5</id>
<content type='text'>
s/capabilitiy/capability

Signed-off-by: Qiujun Huang &lt;hqjagain@gmail.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Link: http://lkml.kernel.org/r/1585818594-27373-1-git-send-email-hqjagain@gmail.com
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>lib/test_lockup: test module to generate lockups</title>
<updated>2020-04-07T17:43:42Z</updated>
<author>
<name>Konstantin Khlebnikov</name>
<email>khlebnikov@yandex-team.ru</email>
</author>
<published>2020-04-07T03:09:47Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=30428ef5d1e8caf78639cc70a802f1cb7b1cec04'/>
<id>urn:sha1:30428ef5d1e8caf78639cc70a802f1cb7b1cec04</id>
<content type='text'>
CONFIG_TEST_LOCKUP=m adds module "test_lockup" that helps to make sure
that watchdogs and lockup detectors are working properly.

Depending on module parameters test_lockup could emulate soft or hard
lockup, "hung task", hold arbitrary lock, allocate bunch of pages.

Also it could generate series of lockups with cooling-down periods, in
this way it could be used as "ping" for locks or page allocator.  Loop
checks signals between iteration thus could be stopped by ^C.

# modinfo test_lockup
...
parm:           time_secs:lockup time in seconds, default 0 (uint)
parm:           time_nsecs:nanoseconds part of lockup time, default 0 (uint)
parm:           cooldown_secs:cooldown time between iterations in seconds, default 0 (uint)
parm:           cooldown_nsecs:nanoseconds part of cooldown, default 0 (uint)
parm:           iterations:lockup iterations, default 1 (uint)
parm:           all_cpus:trigger lockup at all cpus at once (bool)
parm:           state:wait in 'R' running (default), 'D' uninterruptible, 'K' killable, 'S' interruptible state (charp)
parm:           use_hrtimer:use high-resolution timer for sleeping (bool)
parm:           iowait:account sleep time as iowait (bool)
parm:           lock_read:lock read-write locks for read (bool)
parm:           lock_single:acquire locks only at one cpu (bool)
parm:           reacquire_locks:release and reacquire locks/irq/preempt between iterations (bool)
parm:           touch_softlockup:touch soft-lockup watchdog between iterations (bool)
parm:           touch_hardlockup:touch hard-lockup watchdog between iterations (bool)
parm:           call_cond_resched:call cond_resched() between iterations (bool)
parm:           measure_lock_wait:measure lock wait time (bool)
parm:           lock_wait_threshold:print lock wait time longer than this in nanoseconds, default off (ulong)
parm:           disable_irq:disable interrupts: generate hard-lockups (bool)
parm:           disable_softirq:disable bottom-half irq handlers (bool)
parm:           disable_preempt:disable preemption: generate soft-lockups (bool)
parm:           lock_rcu:grab rcu_read_lock: generate rcu stalls (bool)
parm:           lock_mmap_sem:lock mm-&gt;mmap_sem: block procfs interfaces (bool)
parm:           lock_rwsem_ptr:lock rw_semaphore at address (ulong)
parm:           lock_mutex_ptr:lock mutex at address (ulong)
parm:           lock_spinlock_ptr:lock spinlock at address (ulong)
parm:           lock_rwlock_ptr:lock rwlock at address (ulong)
parm:           alloc_pages_nr:allocate and free pages under locks (uint)
parm:           alloc_pages_order:page order to allocate (uint)
parm:           alloc_pages_gfp:allocate pages with this gfp_mask, default GFP_KERNEL (uint)
parm:           alloc_pages_atomic:allocate pages with GFP_ATOMIC (bool)
parm:           reallocate_pages:free and allocate pages between iterations (bool)

Parameters for locking by address are unsafe and taints kernel. With
CONFIG_DEBUG_SPINLOCK=y they at least check magics for embedded spinlocks.

Examples:

task hang in D-state:
modprobe test_lockup time_secs=1 iterations=60 state=D

task hang in io-wait D-state:
modprobe test_lockup time_secs=1 iterations=60 state=D iowait

softlockup:
modprobe test_lockup time_secs=1 iterations=60 state=R

hardlockup:
modprobe test_lockup time_secs=1 iterations=60 state=R disable_irq

system-wide hardlockup:
modprobe test_lockup time_secs=1 iterations=60 state=R \
 disable_irq all_cpus

rcu stall:
modprobe test_lockup time_secs=1 iterations=60 state=R \
 lock_rcu touch_softlockup

lock mmap_sem / block procfs interfaces:
modprobe test_lockup time_secs=1 iterations=60 state=S lock_mmap_sem

lock tasklist_lock for read / block forks:
TASKLIST_LOCK=$(awk '$3 == "tasklist_lock" {print "0x"$1}' /proc/kallsyms)
modprobe test_lockup time_secs=1 iterations=60 state=R \
 disable_irq lock_read lock_rwlock_ptr=$TASKLIST_LOCK

lock namespace_sem / block vfs mount operations:
NAMESPACE_SEM=$(awk '$3 == "namespace_sem" {print "0x"$1}' /proc/kallsyms)
modprobe test_lockup time_secs=1 iterations=60 state=S \
 lock_rwsem_ptr=$NAMESPACE_SEM

lock cgroup mutex / block cgroup operations:
CGROUP_MUTEX=$(awk '$3 == "cgroup_mutex" {print "0x"$1}' /proc/kallsyms)
modprobe test_lockup time_secs=1 iterations=60 state=S \
 lock_mutex_ptr=$CGROUP_MUTEX

ping cgroup_mutex every second and measure maximum lock wait time:
modprobe test_lockup cooldown_secs=1 iterations=60 state=S \
 lock_mutex_ptr=$CGROUP_MUTEX reacquire_locks measure_lock_wait

[linux@roeck-us.net: rename disable_irq to fix build error]
  Link: http://lkml.kernel.org/r/20200317133614.23152-1-linux@roeck-us.net
Signed-off-by: Konstantin Khlebnikov &lt;khlebnikov@yandex-team.ru&gt;
Signed-off-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Sasha Levin &lt;sashal@kernel.org&gt;
Cc: Petr Mladek &lt;pmladek@suse.com&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Sergey Senozhatsky &lt;sergey.senozhatsky@gmail.com&gt;
Cc: Dmitry Monakhov &lt;dmtrmonakhov@yandex-team.ru
Cc: Colin Ian King &lt;colin.king@canonical.com&gt;
Cc: Guenter Roeck &lt;linux@roeck-us.net&gt;
Link: http://lkml.kernel.org/r/158132859146.2797.525923171323227836.stgit@buzz
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>compiler: remove CONFIG_OPTIMIZE_INLINING entirely</title>
<updated>2020-04-07T17:43:42Z</updated>
<author>
<name>Masahiro Yamada</name>
<email>masahiroy@kernel.org</email>
</author>
<published>2020-04-07T03:09:33Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=889b3c1245de48ed0cacf7aebb25c489d3e4a3e9'/>
<id>urn:sha1:889b3c1245de48ed0cacf7aebb25c489d3e4a3e9</id>
<content type='text'>
Commit ac7c3e4ff401 ("compiler: enable CONFIG_OPTIMIZE_INLINING
forcibly") made this always-on option. We released v5.4 and v5.5
including that commit.

Remove the CONFIG option and clean up the code now.

Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Reviewed-by: Miguel Ojeda &lt;miguel.ojeda.sandonis@gmail.com&gt;
Reviewed-by: Nathan Chancellor &lt;natechancellor@gmail.com&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: David Miller &lt;davem@davemloft.net&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: http://lkml.kernel.org/r/20200220110807.32534-2-masahiroy@kernel.org
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'char-misc-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc</title>
<updated>2020-04-03T20:22:40Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-04-03T20:22:40Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=0ad5b053d438990fabaa324499abb6131b9d2202'/>
<id>urn:sha1:0ad5b053d438990fabaa324499abb6131b9d2202</id>
<content type='text'>
Pull char/misc driver updates from Greg KH:
 "Here is the big set of char/misc/other driver patches for 5.7-rc1.

  Lots of things in here, and it's later than expected due to some
  reverts to resolve some reported issues. All is now clean with no
  reported problems in linux-next.

  Included in here is:
   - interconnect updates
   - mei driver updates
   - uio updates
   - nvmem driver updates
   - soundwire updates
   - binderfs updates
   - coresight updates
   - habanalabs updates
   - mhi new bus type and core
   - extcon driver updates
   - some Kconfig cleanups
   - other small misc driver cleanups and updates

  As mentioned, all have been in linux-next for a while, and with the
  last two reverts, all is calm and good"

* tag 'char-misc-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (174 commits)
  Revert "driver core: platform: Initialize dma_parms for platform devices"
  Revert "amba: Initialize dma_parms for amba devices"
  amba: Initialize dma_parms for amba devices
  driver core: platform: Initialize dma_parms for platform devices
  bus: mhi: core: Drop the references to mhi_dev in mhi_destroy_device()
  bus: mhi: core: Initialize bhie field in mhi_cntrl for RDDM capture
  bus: mhi: core: Add support for reading MHI info from device
  misc: rtsx: set correct pcr_ops for rts522A
  speakup: misc: Use dynamic minor numbers for speakup devices
  mei: me: add cedar fork device ids
  coresight: do not use the BIT() macro in the UAPI header
  Documentation: provide IBM contacts for embargoed hardware
  nvmem: core: remove nvmem_sysfs_get_groups()
  nvmem: core: use is_bin_visible for permissions
  nvmem: core: use device_register and device_unregister
  nvmem: core: add root_only member to nvmem device struct
  extcon: axp288: Add wakeup support
  extcon: Mark extcon_get_edev_name() function as exported symbol
  extcon: palmas: Hide error messages if gpio returns -EPROBE_DEFER
  dt-bindings: extcon: usbc-cros-ec: convert extcon-usbc-cros-ec.txt to yaml format
  ...
</content>
</entry>
<entry>
<title>kbuild, btf: Fix dependencies for DEBUG_INFO_BTF</title>
<updated>2020-04-02T22:27:36Z</updated>
<author>
<name>Slava Bacherikov</name>
<email>slava@bacher09.org</email>
</author>
<published>2020-04-02T20:41:39Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=7d32e69310d67e6b04af04f26193f79dfc2f05c7'/>
<id>urn:sha1:7d32e69310d67e6b04af04f26193f79dfc2f05c7</id>
<content type='text'>
Currently turning on DEBUG_INFO_SPLIT when DEBUG_INFO_BTF is also
enabled will produce invalid btf file, since gen_btf function in
link-vmlinux.sh script doesn't handle *.dwo files.

Enabling DEBUG_INFO_REDUCED will also produce invalid btf file,
and using GCC_PLUGIN_RANDSTRUCT with BTF makes no sense.

Fixes: e83b9f55448a ("kbuild: add ability to generate BTF type info for vmlinux")
Reported-by: Jann Horn &lt;jannh@google.com&gt;
Reported-by: Liu Yiding &lt;liuyd.fnst@cn.fujitsu.com&gt;
Signed-off-by: Slava Bacherikov &lt;slava@bacher09.org&gt;
Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Acked-by: KP Singh &lt;kpsingh@google.com&gt;
Acked-by: Andrii Nakryiko &lt;andriin@fb.com&gt;
Link: https://lore.kernel.org/bpf/20200402204138.408021-1-slava@bacher09.org
</content>
</entry>
<entry>
<title>Merge tag 'tty-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty</title>
<updated>2020-03-31T23:18:55Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-03-31T23:18:55Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=1f944f976d7ef8a29d1ad296253d3a9387c58e62'/>
<id>urn:sha1:1f944f976d7ef8a29d1ad296253d3a9387c58e62</id>
<content type='text'>
Pull tty/serial updates from Greg KH:
 "Here is the big set of TTY / Serial patches for 5.7-rc1

  Lots of console fixups and reworking in here, serial core tweaks
  (doesn't that ever get old, why are we still creating new serial
  devices?), serial driver updates, line-protocol driver updates, and
  some vt cleanups and fixes included in here as well.

  All have been in linux-next with no reported issues"

* tag 'tty-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (161 commits)
  serial: 8250: Optimize irq enable after console write
  serial: 8250: Fix rs485 delay after console write
  vt: vt_ioctl: fix use-after-free in vt_in_use()
  vt: vt_ioctl: fix VT_DISALLOCATE freeing in-use virtual console
  tty: serial: make SERIAL_SPRD depend on COMMON_CLK
  tty: serial: fsl_lpuart: fix return value checking
  tty: serial: fsl_lpuart: move dma_request_chan()
  ARM: dts: tango4: Make /serial compatible with ns16550a
  ARM: dts: mmp*: Make the serial ports compatible with xscale-uart
  ARM: dts: mmp*: Fix serial port names
  ARM: dts: mmp2-brownstone: Don't redeclare phandle references
  ARM: dts: pxa*: Make the serial ports compatible with xscale-uart
  ARM: dts: pxa*: Fix serial port names
  ARM: dts: pxa*: Don't redeclare phandle references
  serial: omap: drop unused dt-bindings header
  serial: 8250: 8250_omap: Add DMA support for UARTs on K3 SoCs
  serial: 8250: 8250_omap: Work around errata causing spurious IRQs with DMA
  serial: 8250: 8250_omap: Extend driver data to pass FIFO trigger info
  serial: 8250: 8250_omap: Move locking out from __dma_rx_do_complete()
  serial: 8250: 8250_omap: Account for data in flight during DMA teardown
  ...
</content>
</entry>
<entry>
<title>Merge tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild</title>
<updated>2020-03-31T23:03:39Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-03-31T23:03:39Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=5b67fbfc32b544daa7f4e0f4e0ecdec4e4895938'/>
<id>urn:sha1:5b67fbfc32b544daa7f4e0f4e0ecdec4e4895938</id>
<content type='text'>
Pull Kbuild updates from Masahiro Yamada:
 "Build system:

   - add CONFIG_UNUSED_KSYMS_WHITELIST, which will be useful to define a
     fixed set of export symbols for Generic Kernel Image (GKI)

   - allow to run 'make dt_binding_check' without .config

   - use full schema for checking DT examples in *.yaml files

   - make modpost fail for missing MODULE_IMPORT_NS(), which makes more
     sense because we know the produced modules are never loadable

   - Remove unused 'AS' variable

  Kconfig:

   - sanitize DEFCONFIG_LIST, and remove ARCH_DEFCONFIG from Kconfig
     files

   - relax the 'imply' behavior so that symbols implied by 'y' can
     become 'm'

   - make 'imply' obey 'depends on' in order to make 'imply' really weak

  Misc:

   - add documentation on building the kernel with Clang/LLVM

   - revive __HAVE_ARCH_STRLEN for 32bit sparc to use optimized strlen()

   - fix warning from deb-pkg builds when CONFIG_DEBUG_INFO=n

   - various script and Makefile cleanups"

* tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
  Makefile: Update kselftest help information
  kbuild: deb-pkg: fix warning when CONFIG_DEBUG_INFO is unset
  kbuild: add outputmakefile to no-dot-config-targets
  kbuild: remove AS variable
  net: wan: wanxl: refactor the firmware rebuild rule
  net: wan: wanxl: use $(M68KCC) instead of $(M68KAS) for rebuilding firmware
  net: wan: wanxl: use allow to pass CROSS_COMPILE_M68k for rebuilding firmware
  kbuild: add comment about grouped target
  kbuild: add -Wall to KBUILD_HOSTCXXFLAGS
  kconfig: remove unused variable in qconf.cc
  sparc: revive __HAVE_ARCH_STRLEN for 32bit sparc
  kbuild: refactor Makefile.dtbinst more
  kbuild: compute the dtbs_install destination more simply
  Makefile: disallow data races on gcc-10 as well
  kconfig: make 'imply' obey the direct dependency
  kconfig: allow symbols implied by y to become m
  net: drop_monitor: use IS_REACHABLE() to guard net_dm_hw_report()
  modpost: return error if module is missing ns imports and MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n
  modpost: rework and consolidate logging interface
  kbuild: allow to run dt_binding_check without kernel configuration
  ...
</content>
</entry>
<entry>
<title>Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2020-03-30T23:40:08Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-03-30T23:40:08Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=9b82f05f869a823d43ea4186f5f732f2924d3693'/>
<id>urn:sha1:9b82f05f869a823d43ea4186f5f732f2924d3693</id>
<content type='text'>
Pull perf updates from Ingo Molnar:
 "The main changes in this cycle were:

  Kernel side changes:

   - A couple of x86/cpu cleanups and changes were grandfathered in due
     to patch dependencies. These clean up the set of CPU model/family
     matching macros with a consistent namespace and C99 initializer
     style.

   - A bunch of updates to various low level PMU drivers:
       * AMD Family 19h L3 uncore PMU
       * Intel Tiger Lake uncore support
       * misc fixes to LBR TOS sampling

   - optprobe fixes

   - perf/cgroup: optimize cgroup event sched-in processing

   - misc cleanups and fixes

  Tooling side changes are to:

   - perf {annotate,expr,record,report,stat,test}

   - perl scripting

   - libapi, libperf and libtraceevent

   - vendor events on Intel and S390, ARM cs-etm

   - Intel PT updates

   - Documentation changes and updates to core facilities

   - misc cleanups, fixes and other enhancements"

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (89 commits)
  cpufreq/intel_pstate: Fix wrong macro conversion
  x86/cpu: Cleanup the now unused CPU match macros
  hwrng: via_rng: Convert to new X86 CPU match macros
  crypto: Convert to new CPU match macros
  ASoC: Intel: Convert to new X86 CPU match macros
  powercap/intel_rapl: Convert to new X86 CPU match macros
  PCI: intel-mid: Convert to new X86 CPU match macros
  mmc: sdhci-acpi: Convert to new X86 CPU match macros
  intel_idle: Convert to new X86 CPU match macros
  extcon: axp288: Convert to new X86 CPU match macros
  thermal: Convert to new X86 CPU match macros
  hwmon: Convert to new X86 CPU match macros
  platform/x86: Convert to new CPU match macros
  EDAC: Convert to new X86 CPU match macros
  cpufreq: Convert to new X86 CPU match macros
  ACPI: Convert to new X86 CPU match macros
  x86/platform: Convert to new CPU match macros
  x86/kernel: Convert to new CPU match macros
  x86/kvm: Convert to new CPU match macros
  x86/perf/events: Convert to new CPU match macros
  ...
</content>
</entry>
<entry>
<title>lockdep: Introduce wait-type checks</title>
<updated>2020-03-21T15:00:24Z</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2020-03-21T11:26:01Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=de8f5e4f2dc1f032b46afda0a78cab5456974f89'/>
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Extend lockdep to validate lock wait-type context.

The current wait-types are:

	LD_WAIT_FREE,		/* wait free, rcu etc.. */
	LD_WAIT_SPIN,		/* spin loops, raw_spinlock_t etc.. */
	LD_WAIT_CONFIG,		/* CONFIG_PREEMPT_LOCK, spinlock_t etc.. */
	LD_WAIT_SLEEP,		/* sleeping locks, mutex_t etc.. */

Where lockdep validates that the current lock (the one being acquired)
fits in the current wait-context (as generated by the held stack).

This ensures that there is no attempt to acquire mutexes while holding
spinlocks, to acquire spinlocks while holding raw_spinlocks and so on. In
other words, its a more fancy might_sleep().

Obviously RCU made the entire ordeal more complex than a simple single
value test because RCU can be acquired in (pretty much) any context and
while it presents a context to nested locks it is not the same as it
got acquired in.

Therefore its necessary to split the wait_type into two values, one
representing the acquire (outer) and one representing the nested context
(inner). For most 'normal' locks these two are the same.

[ To make static initialization easier we have the rule that:
  .outer == INV means .outer == .inner; because INV == 0. ]

It further means that its required to find the minimal .inner of the held
stack to compare against the outer of the new lock; because while 'normal'
RCU presents a CONFIG type to nested locks, if it is taken while already
holding a SPIN type it obviously doesn't relax the rules.

Below is an example output generated by the trivial test code:

  raw_spin_lock(&amp;foo);
  spin_lock(&amp;bar);
  spin_unlock(&amp;bar);
  raw_spin_unlock(&amp;foo);

 [ BUG: Invalid wait context ]
 -----------------------------
 swapper/0/1 is trying to lock:
 ffffc90000013f20 (&amp;bar){....}-{3:3}, at: kernel_init+0xdb/0x187
 other info that might help us debug this:
 1 lock held by swapper/0/1:
  #0: ffffc90000013ee0 (&amp;foo){+.+.}-{2:2}, at: kernel_init+0xd1/0x187

The way to read it is to look at the new -{n,m} part in the lock
description; -{3:3} for the attempted lock, and try and match that up to
the held locks, which in this case is the one: -{2,2}.

This tells that the acquiring lock requires a more relaxed environment than
presented by the lock stack.

Currently only the normal locks and RCU are converted, the rest of the
lockdep users defaults to .inner = INV which is ignored. More conversions
can be done when desired.

The check for spinlock_t nesting is not enabled by default. It's a separate
config option for now as there are known problems which are currently
addressed. The config option allows to identify these problems and to
verify that the solutions found are indeed solving them.

The config switch will be removed and the checks will permanently enabled
once the vast majority of issues has been addressed.

[ bigeasy: Move LD_WAIT_FREE,… out of CONFIG_LOCKDEP to avoid compile
	   failure with CONFIG_DEBUG_SPINLOCK + !CONFIG_LOCKDEP]
[ tglx: Add the config option ]

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Signed-off-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Link: https://lkml.kernel.org/r/20200321113242.427089655@linutronix.de
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