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Qian Cai e00d996a43 random: fix data races at timer_rand_state
Fields in "struct timer_rand_state" could be accessed concurrently.
Lockless plain reads and writes result in data races. Fix them by adding
pairs of READ|WRITE_ONCE(). The data races were reported by KCSAN,

 BUG: KCSAN: data-race in add_timer_randomness / add_timer_randomness

 write to 0xffff9f320a0a01d0 of 8 bytes by interrupt on cpu 22:
  add_timer_randomness+0x100/0x190
  add_timer_randomness at drivers/char/random.c:1152
  add_disk_randomness+0x85/0x280
  scsi_end_request+0x43a/0x4a0
  scsi_io_completion+0xb7/0x7e0
  scsi_finish_command+0x1ed/0x2a0
  scsi_softirq_done+0x1c9/0x1d0
  blk_done_softirq+0x181/0x1d0
  __do_softirq+0xd9/0x57c
  irq_exit+0xa2/0xc0
  do_IRQ+0x8b/0x190
  ret_from_intr+0x0/0x42
  cpuidle_enter_state+0x15e/0x980
  cpuidle_enter+0x69/0xc0
  call_cpuidle+0x23/0x40
  do_idle+0x248/0x280
  cpu_startup_entry+0x1d/0x1f
  start_secondary+0x1b2/0x230
  secondary_startup_64+0xb6/0xc0

 no locks held by swapper/22/0.
 irq event stamp: 32871382
 _raw_spin_unlock_irqrestore+0x53/0x60
 _raw_spin_lock_irqsave+0x21/0x60
 _local_bh_enable+0x21/0x30
 irq_exit+0xa2/0xc0

 read to 0xffff9f320a0a01d0 of 8 bytes by interrupt on cpu 2:
  add_timer_randomness+0xe8/0x190
  add_disk_randomness+0x85/0x280
  scsi_end_request+0x43a/0x4a0
  scsi_io_completion+0xb7/0x7e0
  scsi_finish_command+0x1ed/0x2a0
  scsi_softirq_done+0x1c9/0x1d0
  blk_done_softirq+0x181/0x1d0
  __do_softirq+0xd9/0x57c
  irq_exit+0xa2/0xc0
  do_IRQ+0x8b/0x190
  ret_from_intr+0x0/0x42
  cpuidle_enter_state+0x15e/0x980
  cpuidle_enter+0x69/0xc0
  call_cpuidle+0x23/0x40
  do_idle+0x248/0x280
  cpu_startup_entry+0x1d/0x1f
  start_secondary+0x1b2/0x230
  secondary_startup_64+0xb6/0xc0

 no locks held by swapper/2/0.
 irq event stamp: 37846304
 _raw_spin_unlock_irqrestore+0x53/0x60
 _raw_spin_lock_irqsave+0x21/0x60
 _local_bh_enable+0x21/0x30
 irq_exit+0xa2/0xc0

 Reported by Kernel Concurrency Sanitizer on:
 Hardware name: HP ProLiant BL660c Gen9, BIOS I38 10/17/2018

Link: https://lore.kernel.org/r/1582648024-13111-1-git-send-email-cai@lca.pw
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2020-02-27 23:21:53 -05:00
arch arm64: add credited/trusted RNG support 2020-02-27 23:21:52 -05:00
block block-5.6-2020-02-05 2020-02-06 06:15:23 +00:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2020-02-20 15:15:16 -08:00
Documentation fs/zonefs patches for 5.6-rc3 2020-02-22 11:38:20 -08:00
drivers random: fix data races at timer_rand_state 2020-02-27 23:21:53 -05:00
fs for-5.6-rc2-tag 2020-02-23 09:43:50 -08:00
include random: add arch_get_random_*long_early() 2020-02-27 23:21:52 -05:00
init Various fixes: 2020-02-11 16:39:18 -08:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-21 11:22:15 -08:00
kernel Two fixes for the irq core code which are follow ups to the recent MSI 2020-02-22 17:25:46 -08:00
lib lib/stackdepot.c: fix global out-of-bounds in stack_slabs 2020-02-21 11:22:15 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm arm64 fixes for -rc3 2020-02-21 16:03:36 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-02-21 11:59:51 -08:00
samples Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
scripts scripts/get_maintainer.pl: deprioritize old Fixes: addresses 2020-02-21 11:22:15 -08:00
security Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2020-02-20 15:15:16 -08:00
sound ASoC: Fixes for v5.6 2020-02-18 13:33:39 +01:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-02-21 11:59:51 -08:00
usr Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
virt KVM: Disable preemption in kvm_get_running_vcpu() 2020-02-12 12:19:35 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap A handful of small documentation fixes that wandered in. 2020-02-07 13:03:10 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS open: introduce openat2(2) syscall 2020-01-18 09:19:18 -05:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS csky updates for 5.6-rc3 2020-02-23 09:37:41 -08:00
Makefile Linux 5.6-rc3 2020-02-23 16:17:42 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.