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Don Brace 4f7b6eef79 scsi: hpsa: correct race condition in offload enabled
[ Upstream commit 3e16e83a62edac7617bfd8dbb4e55d04ff6adbe1 ]

Correct race condition where ioaccel is re-enabled before the raid_map is
updated. For RAID_1, RAID_1ADM, and RAID 5/6 there is a BUG_ON called which
is bad.

 - Change event thread to disable ioaccel only. Send all requests down the
   RAID path instead.

 - Have rescan thread handle offload_enable.

 - Since there is only one rescan allowed at a time, turning
   offload_enabled on/off should not be racy. Each handler queues up a
   rescan if one is already in progress.

  - For timing diagram, offload_enabled is initially off due to a change
    (transformation: splitmirror/remirror), ...

  otbe = offload_to_be_enabled
  oe   = offload_enabled

  Time Event         Rescan              Completion     Request
       Worker        Worker              Thread         Thread
  ---- ------        ------              ----------     -------
   T0   |             |                       + UA      |
   T1   |             + rescan started        | 0x3f    |
   T2   + Event       |                       | 0x0e    |
   T3   + Ack msg     |                       |         |
   T4   |             + if (!dev[i]->oe &&    |         |
   T5   |             |     dev[i]->otbe)     |         |
   T6   |             |      get_raid_map     |         |
   T7   + otbe = 1    |                       |         |
   T8   |             |                       |         |
   T9   |             + oe = otbe             |         |
   T10  |             |                       |         + ioaccel request
   T11                                                  * BUG_ON

  T0 - I/O completion with UA 0x3f 0x0e sets rescan flag.
  T1 - rescan worker thread starts a rescan.
  T2 - event comes in
  T3 - event thread starts and issues "Acknowledge" message
  ...
  T6 - rescan thread has bypassed code to reload new raid map.
  ...
  T7 - event thread runs and sets offload_to_be_enabled
  ...
  T9 - rescan thread turns on offload_enabled.
  T10- request comes in and goes down ioaccel path.
  T11- BUG_ON.

 - After the patch is applied, ioaccel_enabled can only be re-enabled in
   the re-scan thread.

Link: https://lore.kernel.org/r/158472877894.14200.7077843399036368335.stgit@brunhilda
Reviewed-by: Scott Teel <scott.teel@microsemi.com>
Reviewed-by: Matt Perricone <matt.perricone@microsemi.com>
Reviewed-by: Scott Benesh <scott.benesh@microsemi.com>
Signed-off-by: Don Brace <don.brace@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-01 13:17:50 +02:00
arch KVM: LAPIC: Mark hrtimer for period or oneshot mode to expire in hard interrupt context 2020-10-01 13:17:45 +02:00
block block: only call sched requeue_request() for scheduled requests 2020-09-23 12:40:37 +02:00
certs
crypto crypto: af_alg - Work around empty control messages without MSG_MORE 2020-09-03 11:27:05 +02:00
Documentation affs: fix basic permission bits to actually work 2020-09-09 19:12:34 +02:00
drivers scsi: hpsa: correct race condition in offload enabled 2020-10-01 13:17:50 +02:00
fs xfs: prohibit fs freezing when using empty transactions 2020-10-01 13:17:49 +02:00
include exec: Add exec_update_mutex to replace cred_guard_mutex 2020-10-01 13:17:47 +02:00
init exec: Add exec_update_mutex to replace cred_guard_mutex 2020-10-01 13:17:47 +02:00
ipc
kernel perf: Use new infrastructure to fix deadlocks in execve 2020-10-01 13:17:48 +02:00
lib kernel/sysctl-test: Add null pointer test for sysctl.c:proc_dointvec() 2020-10-01 13:17:10 +02:00
LICENSES
mm mm: avoid data corruption on CoW fault into PFN-mapped VMA 2020-10-01 13:17:39 +02:00
net Bluetooth: L2CAP: handle l2cap config request during open state 2020-10-01 13:17:41 +02:00
samples bpf: Fix fds_example SIGSEGV error 2020-08-19 08:16:03 +02:00
scripts checkpatch: fix the usage of capture group ( ... ) 2020-09-09 19:12:37 +02:00
security selinux: sel_avc_get_stat_idx should increase position index 2020-10-01 13:17:32 +02:00
sound ASoC: SOF: ipc: check ipc return value before data copy 2020-10-01 13:17:37 +02:00
tools selftests/ptrace: add test cases for dead-locks 2020-10-01 13:17:48 +02:00
usr
virt KVM: fix overflow of zero page refcount with ksm running 2020-10-01 13:17:31 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.68 2020-09-26 18:03:16 +02:00
README

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.