1. 30 1月, 2019 1 次提交
  2. 27 1月, 2019 1 次提交
    • Q
      sched/topology: Introduce a sysctl for Energy Aware Scheduling · 8d5d0cfb
      Quentin Perret 提交于
      In its current state, Energy Aware Scheduling (EAS) starts automatically
      on asymmetric platforms having an Energy Model (EM). However, there are
      users who want to have an EM (for thermal management for example), but
      don't want EAS with it.
      
      In order to let users disable EAS explicitly, introduce a new sysctl
      called 'sched_energy_aware'. It is enabled by default so that EAS can
      start automatically on platforms where it makes sense. Flipping it to 0
      rebuilds the scheduling domains and disables EAS.
      Signed-off-by: NQuentin Perret <quentin.perret@arm.com>
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: adharmap@codeaurora.org
      Cc: chris.redpath@arm.com
      Cc: currojerez@riseup.net
      Cc: dietmar.eggemann@arm.com
      Cc: edubezval@gmail.com
      Cc: gregkh@linuxfoundation.org
      Cc: javi.merino@kernel.org
      Cc: joel@joelfernandes.org
      Cc: juri.lelli@redhat.com
      Cc: morten.rasmussen@arm.com
      Cc: patrick.bellasi@arm.com
      Cc: pkondeti@codeaurora.org
      Cc: rjw@rjwysocki.net
      Cc: skannan@codeaurora.org
      Cc: smuckle@google.com
      Cc: srinivas.pandruvada@linux.intel.com
      Cc: thara.gopinath@linaro.org
      Cc: tkjos@google.com
      Cc: valentin.schneider@arm.com
      Cc: vincent.guittot@linaro.org
      Cc: viresh.kumar@linaro.org
      Link: https://lkml.kernel.org/r/20181203095628.11858-11-quentin.perret@arm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      8d5d0cfb
  3. 20 1月, 2019 1 次提交
  4. 19 1月, 2019 1 次提交
  5. 17 1月, 2019 2 次提交
  6. 15 1月, 2019 2 次提交
  7. 13 1月, 2019 1 次提交
  8. 12 1月, 2019 4 次提交
    • T
      net: bpfilter: disallow to remove bpfilter module while being used · 71a85084
      Taehee Yoo 提交于
      The bpfilter.ko module can be removed while functions of the bpfilter.ko
      are executing. so panic can occurred. in order to protect that, locks can
      be used. a bpfilter_lock protects routines in the
      __bpfilter_process_sockopt() but it's not enough because __exit routine
      can be executed concurrently.
      
      Now, the bpfilter_umh can not run in parallel.
      So, the module do not removed while it's being used and it do not
      double-create UMH process.
      The members of the umh_info and the bpfilter_umh_ops are protected by
      the bpfilter_umh_ops.lock.
      
      test commands:
         while :
         do
      	iptables -I FORWARD -m string --string ap --algo kmp &
      	modprobe -rv bpfilter &
         done
      
      splat looks like:
      [  298.623435] BUG: unable to handle kernel paging request at fffffbfff807440b
      [  298.628512] #PF error: [normal kernel read fault]
      [  298.633018] PGD 124327067 P4D 124327067 PUD 11c1a3067 PMD 119eb2067 PTE 0
      [  298.638859] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
      [  298.638859] CPU: 0 PID: 2997 Comm: iptables Not tainted 4.20.0+ #154
      [  298.638859] RIP: 0010:__mutex_lock+0x6b9/0x16a0
      [  298.638859] Code: c0 00 00 e8 89 82 ff ff 80 bd 8f fc ff ff 00 0f 85 d9 05 00 00 48 8b 85 80 fc ff ff 48 bf 00 00 00 00 00 fc ff df 48 c1 e8 03 <80> 3c 38 00 0f 85 1d 0e 00 00 48 8b 85 c8 fc ff ff 49 39 47 58 c6
      [  298.638859] RSP: 0018:ffff88810e7777a0 EFLAGS: 00010202
      [  298.638859] RAX: 1ffffffff807440b RBX: ffff888111bd4d80 RCX: 0000000000000000
      [  298.638859] RDX: 1ffff110235ff806 RSI: ffff888111bd5538 RDI: dffffc0000000000
      [  298.638859] RBP: ffff88810e777b30 R08: 0000000080000002 R09: 0000000000000000
      [  298.638859] R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff168a42c
      [  298.638859] R13: ffff888111bd4d80 R14: ffff8881040e9a05 R15: ffffffffc03a2000
      [  298.638859] FS:  00007f39e3758700(0000) GS:ffff88811ae00000(0000) knlGS:0000000000000000
      [  298.638859] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      [  298.638859] CR2: fffffbfff807440b CR3: 000000011243e000 CR4: 00000000001006f0
      [  298.638859] Call Trace:
      [  298.638859]  ? mutex_lock_io_nested+0x1560/0x1560
      [  298.638859]  ? kasan_kmalloc+0xa0/0xd0
      [  298.638859]  ? kmem_cache_alloc+0x1c2/0x260
      [  298.638859]  ? __alloc_file+0x92/0x3c0
      [  298.638859]  ? alloc_empty_file+0x43/0x120
      [  298.638859]  ? alloc_file_pseudo+0x220/0x330
      [  298.638859]  ? sock_alloc_file+0x39/0x160
      [  298.638859]  ? __sys_socket+0x113/0x1d0
      [  298.638859]  ? __x64_sys_socket+0x6f/0xb0
      [  298.638859]  ? do_syscall_64+0x138/0x560
      [  298.638859]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
      [  298.638859]  ? __alloc_file+0x92/0x3c0
      [  298.638859]  ? init_object+0x6b/0x80
      [  298.638859]  ? cyc2ns_read_end+0x10/0x10
      [  298.638859]  ? cyc2ns_read_end+0x10/0x10
      [  298.638859]  ? hlock_class+0x140/0x140
      [  298.638859]  ? sched_clock_local+0xd4/0x140
      [  298.638859]  ? sched_clock_local+0xd4/0x140
      [  298.638859]  ? check_flags.part.37+0x440/0x440
      [  298.638859]  ? __lock_acquire+0x4f90/0x4f90
      [  298.638859]  ? set_rq_offline.part.89+0x140/0x140
      [ ... ]
      
      Fixes: d2ba09c1 ("net: add skeleton of bpfilter kernel module")
      Signed-off-by: NTaehee Yoo <ap420073@gmail.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      71a85084
    • T
      net: bpfilter: restart bpfilter_umh when error occurred · 61fbf593
      Taehee Yoo 提交于
      The bpfilter_umh will be stopped via __stop_umh() when the bpfilter
      error occurred.
      The bpfilter_umh() couldn't start again because there is no restart
      routine.
      
      The section of the bpfilter_umh_{start/end} is no longer .init.rodata
      because these area should be reused in the restart routine. hence
      the section name is changed to .bpfilter_umh.
      
      The bpfilter_ops->start() is restart callback. it will be called when
      bpfilter_umh is stopped.
      The stop bit means bpfilter_umh is stopped. this bit is set by both
      start and stop routine.
      
      Before this patch,
      Test commands:
         $ iptables -vnL
         $ kill -9 <pid of bpfilter_umh>
         $ iptables -vnL
         [  480.045136] bpfilter: write fail -32
         $ iptables -vnL
      
      All iptables commands will fail.
      
      After this patch,
      Test commands:
         $ iptables -vnL
         $ kill -9 <pid of bpfilter_umh>
         $ iptables -vnL
         $ iptables -vnL
      
      Now, all iptables commands will work.
      
      Fixes: d2ba09c1 ("net: add skeleton of bpfilter kernel module")
      Signed-off-by: NTaehee Yoo <ap420073@gmail.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      61fbf593
    • T
      net: bpfilter: use cleanup callback to release umh_info · 5b4cb650
      Taehee Yoo 提交于
      Now, UMH process is killed, do_exit() calls the umh_info->cleanup callback
      to release members of the umh_info.
      This patch makes bpfilter_umh's cleanup routine to use the
      umh_info->cleanup callback.
      Signed-off-by: NTaehee Yoo <ap420073@gmail.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5b4cb650
    • T
      umh: add exit routine for UMH process · 73ab1cb2
      Taehee Yoo 提交于
      A UMH process which is created by the fork_usermode_blob() such as
      bpfilter needs to release members of the umh_info when process is
      terminated.
      But the do_exit() does not release members of the umh_info. hence module
      which uses UMH needs own code to detect whether UMH process is
      terminated or not.
      But this implementation needs extra code for checking the status of
      UMH process. it eventually makes the code more complex.
      
      The new PF_UMH flag is added and it is used to identify UMH processes.
      The exit_umh() does not release members of the umh_info.
      Hence umh_info->cleanup callback should release both members of the
      umh_info and the private data.
      Suggested-by: NDavid S. Miller <davem@davemloft.net>
      Signed-off-by: NTaehee Yoo <ap420073@gmail.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      73ab1cb2
  9. 11 1月, 2019 2 次提交
  10. 10 1月, 2019 1 次提交
    • R
      MIPS: BCM47XX: Setup struct device for the SoC · 321c46b9
      Rafał Miłecki 提交于
      So far we never had any device registered for the SoC. This resulted in
      some small issues that we kept ignoring like:
      1) Not working GPIOLIB_IRQCHIP (gpiochip_irqchip_add_key() failing)
      2) Lack of proper tree in the /sys/devices/
      3) mips_dma_alloc_coherent() silently handling empty coherent_dma_mask
      
      Kernel 4.19 came with a lot of DMA changes and caused a regression on
      bcm47xx. Starting with the commit f8c55dc6 ("MIPS: use generic dma
      noncoherent ops for simple noncoherent platforms") DMA coherent
      allocations just fail. Example:
      [    1.114914] bgmac_bcma bcma0:2: Allocation of TX ring 0x200 failed
      [    1.121215] bgmac_bcma bcma0:2: Unable to alloc memory for DMA
      [    1.127626] bgmac_bcma: probe of bcma0:2 failed with error -12
      [    1.133838] bgmac_bcma: Broadcom 47xx GBit MAC driver loaded
      
      The bgmac driver also triggers a WARNING:
      [    0.959486] ------------[ cut here ]------------
      [    0.964387] WARNING: CPU: 0 PID: 1 at ./include/linux/dma-mapping.h:516 bgmac_enet_probe+0x1b4/0x5c4
      [    0.973751] Modules linked in:
      [    0.976913] CPU: 0 PID: 1 Comm: swapper Not tainted 4.19.9 #0
      [    0.982750] Stack : 804a0000 804597c4 00000000 00000000 80458fd8 8381bc2c 838282d4 80481a47
      [    0.991367]         8042e3ec 00000001 804d38f0 00000204 83980000 00000065 8381bbe0 6f55b24f
      [    0.999975]         00000000 00000000 80520000 00002018 00000000 00000075 00000007 00000000
      [    1.008583]         00000000 80480000 000ee811 00000000 00000000 00000000 80432c00 80248db8
      [    1.017196]         00000009 00000204 83980000 803ad7b0 00000000 801feeec 00000000 804d0000
      [    1.025804]         ...
      [    1.028325] Call Trace:
      [    1.030875] [<8000aef8>] show_stack+0x58/0x100
      [    1.035513] [<8001f8b4>] __warn+0xe4/0x118
      [    1.039708] [<8001f9a4>] warn_slowpath_null+0x48/0x64
      [    1.044935] [<80248db8>] bgmac_enet_probe+0x1b4/0x5c4
      [    1.050101] [<802498e0>] bgmac_probe+0x558/0x590
      [    1.054906] [<80252fd0>] bcma_device_probe+0x38/0x70
      [    1.060017] [<8020e1e8>] really_probe+0x170/0x2e8
      [    1.064891] [<8020e714>] __driver_attach+0xa4/0xec
      [    1.069784] [<8020c1e0>] bus_for_each_dev+0x58/0xb0
      [    1.074833] [<8020d590>] bus_add_driver+0xf8/0x218
      [    1.079731] [<8020ef24>] driver_register+0xcc/0x11c
      [    1.084804] [<804b54cc>] bgmac_init+0x1c/0x44
      [    1.089258] [<8000121c>] do_one_initcall+0x7c/0x1a0
      [    1.094343] [<804a1d34>] kernel_init_freeable+0x150/0x218
      [    1.099886] [<803a082c>] kernel_init+0x10/0x104
      [    1.104583] [<80005878>] ret_from_kernel_thread+0x14/0x1c
      [    1.110107] ---[ end trace f441c0d873d1fb5b ]---
      
      This patch setups a "struct device" (and passes it to the bcma) which
      allows fixing all the mentioned problems. It'll also require a tiny bcma
      patch which will follow through the wireless tree & its maintainer.
      
      Fixes: f8c55dc6 ("MIPS: use generic dma noncoherent ops for simple noncoherent platforms")
      Signed-off-by: NRafał Miłecki <rafal@milecki.pl>
      Signed-off-by: NPaul Burton <paul.burton@mips.com>
      Acked-by: NHauke Mehrtens <hauke@hauke-m.de>
      Cc: Christoph Hellwig <hch@lst.de>
      Cc: Linus Walleij <linus.walleij@linaro.org>
      Cc: linux-wireless@vger.kernel.org
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: James Hogan <jhogan@kernel.org>
      Cc: linux-mips@linux-mips.org
      Cc: linux-kernel@vger.kernel.org
      Cc: stable@vger.kernel.org # v4.19+
      321c46b9
  11. 09 1月, 2019 5 次提交
    • M
      include/linux/compiler*.h: fix OPTIMIZER_HIDE_VAR · 3e2ffd65
      Michael S. Tsirkin 提交于
      Since commit 815f0ddb ("include/linux/compiler*.h: make compiler-*.h
      mutually exclusive") clang no longer reuses the OPTIMIZER_HIDE_VAR macro
      from compiler-gcc - instead it gets the version in
      include/linux/compiler.h.  Unfortunately that version doesn't actually
      prevent compiler from optimizing out the variable.
      
      Fix up by moving the macro out from compiler-gcc.h to compiler.h.
      Compilers without incline asm support will keep working
      since it's protected by an ifdef.
      
      Also fix up comments to match reality since we are no longer overriding
      any macros.
      
      Build-tested with gcc and clang.
      
      Fixes: 815f0ddb ("include/linux/compiler*.h: make compiler-*.h mutually exclusive")
      Cc: Eli Friedman <efriedma@codeaurora.org>
      Cc: Joe Perches <joe@perches.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Reviewed-by: NNick Desaulniers <ndesaulniers@google.com>
      Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
      Signed-off-by: NMiguel Ojeda <miguel.ojeda.sandonis@gmail.com>
      3e2ffd65
    • W
      x86, modpost: Replace last remnants of RETPOLINE with CONFIG_RETPOLINE · e4f35891
      WANG Chao 提交于
      Commit
      
        4cd24de3 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support")
      
      replaced the RETPOLINE define with CONFIG_RETPOLINE checks. Remove the
      remaining pieces.
      
       [ bp: Massage commit message. ]
      
      Fixes: 4cd24de3 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support")
      Signed-off-by: NWANG Chao <chao.wang@ucloud.cn>
      Signed-off-by: NBorislav Petkov <bp@suse.de>
      Reviewed-by: NZhenzhong Duan <zhenzhong.duan@oracle.com>
      Reviewed-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Andi Kleen <ak@linux.intel.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Daniel Borkmann <daniel@iogearbox.net>
      Cc: David Woodhouse <dwmw@amazon.co.uk>
      Cc: Geert Uytterhoeven <geert@linux-m68k.org>
      Cc: Jessica Yu <jeyu@kernel.org>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
      Cc: Michal Marek <michal.lkml@markovi.net>
      Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Tim Chen <tim.c.chen@linux.intel.com>
      Cc: Vasily Gorbik <gor@linux.ibm.com>
      Cc: linux-kbuild@vger.kernel.org
      Cc: srinivas.eeda@oracle.com
      Cc: stable <stable@vger.kernel.org>
      Cc: x86-ml <x86@kernel.org>
      Link: https://lkml.kernel.org/r/20181210163725.95977-1-chao.wang@ucloud.cn
      e4f35891
    • B
      x86/cache: Rename config option to CONFIG_X86_RESCTRL · 90802938
      Borislav Petkov 提交于
      CONFIG_RESCTRL is too generic. The final goal is to have a generic
      option called like this which is selected by the arch-specific ones
      CONFIG_X86_RESCTRL and CONFIG_ARM64_RESCTRL. The generic one will
      cover the resctrl filesystem and other generic and shared bits of
      functionality.
      Signed-off-by: NBorislav Petkov <bp@suse.de>
      Suggested-by: NIngo Molnar <mingo@kernel.org>
      Requested-by: NLinus Torvalds <torvalds@linux-foundation.org>
      Cc: Babu Moger <babu.moger@amd.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: James Morse <james.morse@arm.com>
      Cc: Reinette Chatre <reinette.chatre@intel.com>
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: x86@kernel.org
      Link: http://lkml.kernel.org/r/20190108171401.GC12235@zn.tnic
      90802938
    • D
      libnvdimm/dimm: Fix security capability detection for non-Intel NVDIMMs · 1cb95e07
      Dan Williams 提交于
      Kees reports a crash with the following signature...
      
       RIP: 0010:nvdimm_visible+0x79/0x80
       [..]
       Call Trace:
        internal_create_group+0xf4/0x380
        sysfs_create_groups+0x46/0xb0
        device_add+0x331/0x680
        nd_async_device_register+0x15/0x60
        async_run_entry_fn+0x38/0x100
      
      ...when starting a QEMU environment with "label-less" DIMM. Without
      labels QEMU does not publish any DSM methods. Without defined methods
      the NVDIMM_FAMILY type is not established and the nfit driver will skip
      registering security operations.
      
      In that case the security state should be initialized to a negative
      value in __nvdimm_create() and nvdimm_visible() should skip
      interrogating the specific ops. However, since 'enum
      nvdimm_security_state' was only defined to contain positive values the
      "if (nvdimm->sec.state < 0)" check always fails.
      
      Define a negative error state to allow negative state values to be
      handled as expected.
      
      Fixes: f2989396 ("acpi/nfit, libnvdimm: Introduce nvdimm_security_ops")
      Reviewed-by: NDave Jiang <dave.jiang@intel.com>
      Reported-by: NKees Cook <keescook@chromium.org>
      Tested-by: NKees Cook <keescook@chromium.org>
      Signed-off-by: NDan Williams <dan.j.williams@intel.com>
      1cb95e07
    • M
      mm, page_alloc: do not wake kswapd with zone lock held · 73444bc4
      Mel Gorman 提交于
      syzbot reported the following regression in the latest merge window and
      it was confirmed by Qian Cai that a similar bug was visible from a
      different context.
      
        ======================================================
        WARNING: possible circular locking dependency detected
        4.20.0+ #297 Not tainted
        ------------------------------------------------------
        syz-executor0/8529 is trying to acquire lock:
        000000005e7fb829 (&pgdat->kswapd_wait){....}, at:
        __wake_up_common_lock+0x19e/0x330 kernel/sched/wait.c:120
      
        but task is already holding lock:
        000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at: spin_lock
        include/linux/spinlock.h:329 [inline]
        000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at: rmqueue_bulk
        mm/page_alloc.c:2548 [inline]
        000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at: __rmqueue_pcplist
        mm/page_alloc.c:3021 [inline]
        000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at: rmqueue_pcplist
        mm/page_alloc.c:3050 [inline]
        000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at: rmqueue
        mm/page_alloc.c:3072 [inline]
        000000009bb7bae0 (&(&zone->lock)->rlock){-.-.}, at:
        get_page_from_freelist+0x1bae/0x52a0 mm/page_alloc.c:3491
      
      It appears to be a false positive in that the only way the lock ordering
      should be inverted is if kswapd is waking itself and the wakeup
      allocates debugging objects which should already be allocated if it's
      kswapd doing the waking.  Nevertheless, the possibility exists and so
      it's best to avoid the problem.
      
      This patch flags a zone as needing a kswapd using the, surprisingly,
      unused zone flag field.  The flag is read without the lock held to do
      the wakeup.  It's possible that the flag setting context is not the same
      as the flag clearing context or for small races to occur.  However, each
      race possibility is harmless and there is no visible degredation in
      fragmentation treatment.
      
      While zone->flag could have continued to be unused, there is potential
      for moving some existing fields into the flags field instead.
      Particularly read-mostly ones like zone->initialized and
      zone->contiguous.
      
      Link: http://lkml.kernel.org/r/20190103225712.GJ31517@techsingularity.net
      Fixes: 1c30844d ("mm: reclaim small amounts of memory when an external fragmentation event occurs")
      Reported-by: syzbot+93d94a001cfbce9e60e1@syzkaller.appspotmail.com
      Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
      Acked-by: NVlastimil Babka <vbabka@suse.cz>
      Tested-by: NQian Cai <cai@lca.pw>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Michal Hocko <mhocko@suse.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      73444bc4
  12. 08 1月, 2019 3 次提交
  13. 07 1月, 2019 2 次提交
  14. 06 1月, 2019 2 次提交
  15. 05 1月, 2019 11 次提交
  16. 04 1月, 2019 1 次提交
    • V
      cpufreq: scpi/scmi: Fix freeing of dynamic OPPs · 1690d8bb
      Viresh Kumar 提交于
      Since the commit 2a4eb735 "OPP: Don't remove dynamic OPPs from
      _dev_pm_opp_remove_table()", dynamically created OPP aren't
      automatically removed anymore by dev_pm_opp_cpumask_remove_table(). This
      affects the scpi and scmi cpufreq drivers which no longer free OPPs on
      failures or on invocations of the policy->exit() callback.
      
      Create a generic OPP helper dev_pm_opp_remove_all_dynamic() which can be
      called from these drivers instead of dev_pm_opp_cpumask_remove_table().
      
      In dev_pm_opp_remove_all_dynamic(), we need to make sure that the
      opp_list isn't getting accessed simultaneously from other parts of the
      OPP core while the helper is freeing dynamic OPPs, i.e. we can't drop
      the opp_table->lock while traversing through the OPP list. And to
      accomplish that, this patch also creates _opp_kref_release_unlocked()
      which can be called from this new helper with the opp_table lock already
      held.
      
      Cc: 4.20 <stable@vger.kernel.org> # v4.20
      Reported-by: NValentin Schneider <valentin.schneider@arm.com>
      Fixes: 2a4eb735 "OPP: Don't remove dynamic OPPs from _dev_pm_opp_remove_table()"
      Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
      Tested-by: NValentin Schneider <valentin.schneider@arm.com>
      Reviewed-by: NSudeep Holla <sudeep.holla@arm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      1690d8bb