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Suzuki K Poulose c48fb3bbe9 coresight: perf: Avoid unncessary CPU hotplug read lock 
We hold the read lock on CPU hotplug to simply copy the
online mask, which is not really needed. And this can
cause a lockdep warning, like :

[   54.632093] ======================================================
[   54.638207] WARNING: possible circular locking dependency detected
[   54.644322] 4.18.0-rc3-00042-g2d39e6356bb7-dirty #309 Not tainted
[   54.650350] ------------------------------------------------------
[   54.656464] perf/2862 is trying to acquire lock:
[   54.661031] 000000007e21d170 (&event->mmap_mutex){+.+.}, at: perf_event_set_output+0x98/0x138
[   54.669486]
[   54.669486] but task is already holding lock:
[   54.675256] 000000001080eb1b (&cpuctx_mutex){+.+.}, at: perf_event_ctx_lock_nested+0xf8/0x1f0
[   54.683704]
[   54.683704] which lock already depends on the new lock.
[   54.683704]
[   54.691797]
[   54.691797] the existing dependency chain (in reverse order) is:
[   54.699201]
[   54.699201] -> #3 (&cpuctx_mutex){+.+.}:
[   54.704556]        __mutex_lock+0x70/0x808
[   54.708608]        mutex_lock_nested+0x1c/0x28
[   54.713005]        perf_event_init_cpu+0x8c/0xd8
[   54.717574]        perf_event_init+0x194/0x1d4
[   54.721971]        start_kernel+0x2b8/0x42c
[   54.726107]
[   54.726107] -> #2 (pmus_lock){+.+.}:
[   54.731114]        __mutex_lock+0x70/0x808
[   54.735165]        mutex_lock_nested+0x1c/0x28
[   54.739560]        perf_event_init_cpu+0x30/0xd8
[   54.744129]        cpuhp_invoke_callback+0x84/0x248
[   54.748954]        _cpu_up+0xe8/0x1c8
[   54.752576]        do_cpu_up+0xa8/0xc8
[   54.756283]        cpu_up+0x10/0x18
[   54.759731]        smp_init+0xa0/0x114
[   54.763438]        kernel_init_freeable+0x120/0x288
[   54.768264]        kernel_init+0x10/0x108
[   54.772230]        ret_from_fork+0x10/0x18
[   54.776279]
[   54.776279] -> #1 (cpu_hotplug_lock.rw_sem){++++}:
[   54.782492]        cpus_read_lock+0x34/0xb0
[   54.786631]        etm_setup_aux+0x5c/0x308
[   54.790769]        rb_alloc_aux+0x1ec/0x300
[   54.794906]        perf_mmap+0x284/0x610
[   54.798787]        mmap_region+0x388/0x570
[   54.802838]        do_mmap+0x344/0x4f8
[   54.806544]        vm_mmap_pgoff+0xe4/0x110
[   54.810682]        ksys_mmap_pgoff+0xa8/0x240
[   54.814992]        sys_mmap+0x18/0x28
[   54.818613]        el0_svc_naked+0x30/0x34
[   54.822661]
[   54.822661] -> #0 (&event->mmap_mutex){+.+.}:
[   54.828445]        lock_acquire+0x48/0x68
[   54.832409]        __mutex_lock+0x70/0x808
[   54.836459]        mutex_lock_nested+0x1c/0x28
[   54.840855]        perf_event_set_output+0x98/0x138
[   54.845680]        _perf_ioctl+0x2a0/0x6a0
[   54.849731]        perf_ioctl+0x3c/0x68
[   54.853526]        do_vfs_ioctl+0xb8/0xa20
[   54.857577]        ksys_ioctl+0x80/0xb8
[   54.861370]        sys_ioctl+0xc/0x18
[   54.864990]        el0_svc_naked+0x30/0x34
[   54.869039]
[   54.869039] other info that might help us debug this:
[   54.869039]
[   54.876960] Chain exists of:
[   54.876960]   &event->mmap_mutex --> pmus_lock --> &cpuctx_mutex
[   54.876960]
[   54.887217]  Possible unsafe locking scenario:
[   54.887217]
[   54.893073]        CPU0                    CPU1
[   54.897552]        ----                    ----
[   54.902030]   lock(&cpuctx_mutex);
[   54.905396]                                lock(pmus_lock);
[   54.910911]                                lock(&cpuctx_mutex);
[   54.916770]   lock(&event->mmap_mutex);
[   54.920566]
[   54.920566]  *** DEADLOCK ***
[   54.920566]
[   54.926424] 1 lock held by perf/2862:
[   54.930042]  #0: 000000001080eb1b (&cpuctx_mutex){+.+.}, at: perf_event_ctx_lock_nested+0xf8/0x1f0

Since we have per-cpu array for the paths, we simply don't care about
the number of online CPUs. This patch gets rid of the
{get/put}_online_cpus().

Reported-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2018-09-25 20:09:17 +02:00
..
accessibility
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acpi Merge branch 'acpi-bus' 2018-09-07 10:05:20 +02:00
amba
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android Merge b4.19-rc4 into char-misc-next 2018-09-16 22:41:47 +02:00
ata SCSI fixes on 20180905 2018-09-05 09:17:20 -07:00
atm
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auxdisplay Char/Misc driver patches for 4.19-rc1 2018-08-18 11:04:51 -07:00
base firmware: Fix security issue with request_firmware_into_buf() 2018-09-12 09:31:00 +02:00
bcma
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block for-linus-20180913 2018-09-13 19:16:11 -10:00
bluetooth Bluetooth: mediatek: Fix memory leak 2018-08-21 16:56:20 +02:00
bus Merge branch 'perm-fix' into omap-for-v4.19/fixes-v2 2018-08-28 09:58:03 -07:00
cdrom cdrom: Fix info leak/OOB read in cdrom_ioctl_drive_status 2018-08-29 08:09:20 -06:00
char A few fixes that came around or after the merge window, except 2018-09-12 19:33:56 -10:00
clk clk: x86: Set default parent to 48Mhz 2018-08-30 14:47:41 -07:00
clocksource RISC-V Updates for the 4.19 Merge Window 2018-08-19 09:56:38 -07:00
connector
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cpufreq ARM: SoC driver updates 2018-08-23 13:52:46 -07:00
cpuidle cpuidle: menu: Retain tick when shallow state is selected 2018-08-25 13:16:08 +02:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-08-29 13:38:39 -07:00
dax drivers/dax/device.c: convert variable to vm_fault_t type 2018-09-04 16:45:02 -07:00
dca
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devfreq Char/Misc driver patches for 4.19-rc1 2018-08-18 11:04:51 -07:00
dio
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dma dmaengine: mic_x100_dma: use devm_kzalloc to fix an issue 2018-08-27 11:16:04 +05:30
dma-buf
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edac EDAC: Add missing MEM_LRDDR4 entry in edac_mem_types[] 2018-08-17 15:13:34 +02:00
eisa
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extcon
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firewire firewire: use 64-bit time_t based interfaces 2018-08-17 16:20:27 -07:00
firmware firmware: coreboot: Only populate devices in coreboot_table_init() 2018-09-14 15:37:23 +02:00
fmc
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fpga Merge b4.19-rc4 into char-misc-next 2018-09-16 22:41:47 +02:00
fsi fsi: sbefifo: Bump max command length 2018-08-08 15:44:47 +10:00
gnss
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gpio gpio: Fix crash due to registration race 2018-08-31 11:30:45 +02:00
gpu Merge branch 'linux-4.19' of git://github.com/skeggsb/linux into drm-fixes 2018-09-14 09:38:42 +10:00
hid HID: i2c-hid: Don't reset device upon system resume 2018-09-06 16:30:53 +02:00
hsi
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hv Merge b4.19-rc4 into char-misc-next 2018-09-16 22:41:47 +02:00
hwmon ARM: SoC fixes 2018-09-08 15:38:57 -07:00
hwspinlock hwspinlock: Fix incorrect return pointers 2018-07-30 20:54:51 -07:00
hwtracing coresight: perf: Avoid unncessary CPU hotplug read lock 2018-09-25 20:09:17 +02:00
i2c i2c: xiic: Make the start and the byte count write atomic 2018-09-06 20:49:09 +02:00
ide Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/ide 2018-08-22 07:40:33 -07:00
idle
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iio First set of IIO fixes for the 4.19 cycle. 2018-09-09 09:33:29 +02:00
infiniband pci-v4.19-fixes-1 2018-09-12 19:39:56 -10:00
input ARM: 32-bit SoC platform updates 2018-08-23 13:44:43 -07:00
iommu ARM: SoC: late updates 2018-08-25 14:12:36 -07:00
ipack
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irqchip irqchip/gic-v3-its: Cap lpi_id_bits to reduce memory footprint 2018-09-06 20:31:59 +02:00
isdn isdn: Disable IIOCDBGVAR 2018-08-16 12:26:24 -07:00
leds leds: ns2: Change unsigned to unsigned int 2018-08-06 23:03:12 +02:00
lightnvm
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macintosh macintosh: therm_windtunnel: drop using attach_adapter 2018-08-24 14:42:42 +02:00
mailbox mailbox: Add support for i.MX messaging unit 2018-08-15 09:53:07 +05:30
mcb
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md - DM verity fix for crash due to using vmalloc'd buffers with the 2018-09-13 19:12:55 -10:00
media Merge branch 'ida-4.19' of git://git.infradead.org/users/willy/linux-dax 2018-08-26 11:48:42 -07:00
memory memory: ti-aemif: fix a potential NULL-pointer dereference 2018-09-06 10:04:07 -07:00
memstick
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message scsi: message: fusion: Replace GFP_ATOMIC with GFP_KERNEL 2018-07-30 23:17:53 -04:00
mfd Merge branch 'i2c/for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2018-08-21 17:40:46 -07:00
misc misc: sgi-gru: fix fall-through annotations 2018-09-20 15:13:52 +02:00
mmc mmc: meson-mx-sdio: fix OF child-node lookup 2018-09-05 08:28:45 +02:00
mtd mtd: rawnand: denali: do not pass zero maxchips to nand_scan() 2018-08-27 20:41:46 +02:00
mux mux: adgs1408: new driver for Analog Devices ADGS1408/1409 mux 2018-08-02 10:23:02 +02:00
net nfp: flower: reject tunnel encap with ipv6 outer headers for offloading 2018-09-12 13:18:30 -07:00
nfc
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ntb
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nubus
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nvdimm libnvdimm-for-4.19_dax-memory-failure 2018-08-25 18:43:59 -07:00
nvme nvmet-rdma: fix possible bogus dereference under heavy load 2018-09-05 12:18:01 -07:00
nvmem nvmem: core: return error code instead of NULL from nvmem_device_get 2018-09-12 09:46:46 +02:00
of Devicetree fixes for 4.19, part 2: 2018-09-14 13:03:17 -10:00
opp
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oprofile
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parisc
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parport Char/Misc driver patches for 4.19-rc1 2018-08-18 11:04:51 -07:00
pci PCI: Fix enabling of PASID on RC integrated endpoints 2018-09-11 21:46:49 -05:00
pcmcia pcmcia: remove long deprecated pcmcia_request_exclusive_irq() function 2018-08-18 12:30:42 -07:00
perf Char/Misc driver patches for 4.19-rc1 2018-08-18 11:04:51 -07:00
phy
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pinctrl pinctrl: madera: Fix possible NULL pointer with pdata config 2018-08-29 14:02:47 +02:00
platform platform: goldfish: pipe: Replace "x==NULL" to "!x" 2018-09-14 15:31:31 +02:00
pnp
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power treewide: convert ISO_8859-1 text comments to utf-8 2018-08-23 18:48:43 -07:00
powercap
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pps
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ps3
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ptp Char/Misc driver patches for 4.19-rc1 2018-08-18 11:04:51 -07:00
pwm pwm: mediatek: Add MT7628 support 2018-08-20 11:36:07 +02:00
rapidio drivers/rapidio/devices/rio_mport_cdev.c: remove redundant pointer md 2018-08-22 10:52:51 -07:00
ras
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regulator - New Drivers 2018-08-20 15:38:44 -07:00
remoteproc remoteproc/davinci: use the reset framework 2018-08-16 17:39:55 -07:00
reset ARM: SoC: late updates 2018-08-25 14:12:36 -07:00
rpmsg rpmsg: Add compat ioctl for rpmsg char driver 2018-07-30 23:40:23 -07:00
rtc RTC for 4.19 2018-08-20 16:30:27 -07:00
s390 s390 fixes for 4.19-rc4 2018-09-13 16:22:24 -10:00
sbus
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scsi scsi: qedi: Add the CRC size within iSCSI NVM image 2018-08-30 07:15:22 -04:00
sfi
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sh sh: introduce a sh_cacheop_vaddr helper 2018-08-02 13:54:06 +02:00
siox
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slimbus slimbus: ngd: mark PM functions as __maybe_unused 2018-09-14 15:36:20 +02:00
sn
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soc ARM: Device-tree updates 2018-08-23 14:02:22 -07:00
soundwire
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spi hwspinlock updates for v4.19 2018-08-18 16:45:27 -07:00
spmi
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ssb ssb: Remove SSB_WARN_ON, SSB_BUG_ON and SSB_DEBUG 2018-08-09 18:47:47 +03:00
staging staging: vboxvideo: Change address of scanout buffer on page-flip 2018-09-11 18:39:54 +02:00
target scsi: iscsi: target: Fix conn_ops double free 2018-08-30 07:07:12 -04:00
tc
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tee ARM: SoC driver updates 2018-08-23 13:52:46 -07:00
thermal Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal 2018-08-28 16:11:34 -07:00
thunderbolt
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tty tty: hvc: hvc_write() fix break condition 2018-09-10 18:04:31 +02:00
uio uio: convert to vm_fault_t 2018-09-12 09:46:46 +02:00
usb Revert "cdc-acm: implement put_char() and flush_chars()" 2018-09-10 20:40:29 +02:00
uwb
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vfio powerpc updates for 4.19 2018-08-17 11:32:50 -07:00
vhost Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-08-27 11:59:39 -07:00
video fbdev changes for v4.19: 2018-08-23 15:44:58 -07:00
virt
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virtio virtio, vhost: fixes, tweaks 2018-08-24 08:45:19 -07:00
visorbus
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vlynq
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vme vme: remove unneeded kfree 2018-09-14 15:25:57 +02:00
w1 power supply and reset changes for the v4.19 series 2018-08-21 18:06:27 -07:00
watchdog include/linux/compiler*.h: make compiler-*.h mutually exclusive 2018-08-22 17:31:34 -07:00
xen xen/gntdev: fix up blockable calls to mn_invl_range_start 2018-09-14 08:52:30 -04:00
zorro
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Kconfig
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Makefile Char/Misc driver patches for 4.19-rc1 2018-08-18 11:04:51 -07:00